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PsyPost – Psychology News Daily Digest (Unofficial)

 

(https://www.psypost.org/scientists-uncover-delayed-effects-of-citalopram-on-brains-reward-system/) Scientists uncover delayed effects of citalopram on brain’s reward system
Mar 20th 2025, 10:00

A new study on mice reveals that the brain’s response to rewards is temporarily suppressed after the first dose of citalopram, an antidepressant, but gradually returns with continued use. The findings, published in the(https://www.sciencedirect.com/science/article/pii/S1347861325000015)  Journal of Pharmacological Sciences, shed light on the neurobiological mechanisms behind the delayed effects of selective serotonin reuptake inhibitors (SSRIs), a commonly prescribed class of antidepressants.
Depression is a debilitating mental health disorder characterized by persistent sadness, loss of interest in daily activities, and an inability to experience pleasure. It affects hundreds of millions worldwide and remains one of the leading causes of disability. Despite the widespread use of antidepressants, at least 30% of patients fail to respond to treatment, highlighting the urgent need for a deeper understanding of how these medications work.
SSRIs, including fluoxetine (Prozac) and citalopram (Celexa), function by increasing serotonin levels in the brain, which is thought to enhance mood and restore normal emotional processing. However, their effects do not take hold immediately—most patients experience a delay of several weeks before noticeable improvements occur. Scientists have long speculated that this lag is due to complex neural adaptations, but the precise mechanisms remain unclear.
To explore this phenomenon, Masashi Koda and colleagues conducted a study on mice, focusing on serotonin-producing neurons in the dorsal raphe nucleus (DRN), a brain region involved in mood regulation and reward processing. Their goal was to determine how citalopram affects neural responses to pleasurable stimuli (such as sugar) after a single dose versus after prolonged treatment. By using fiber photometry, an advanced technique that measures brain activity in real time, they sought to uncover why antidepressants take time to become effective and whether their effects could be accelerated.
The dorsal raphe nucleus is the largest cluster of serotonin-producing neurons in the brainstem. It plays a key role in regulating mood, processes related to the feeling of pleasure (reward processing), and the stress response by projecting serotonin to various brain regions, including the prefrontal cortex and the limbic system.
The study was conducted on adult male C57BL/6JmsSlc mice. The mice were 8-12 weeks old. They were kept in a plastic cage with wooden bedding and had free access to food and water.
Study authors applied a technique called fiber photometry to study the activity of neural cells of interest in the brains of these mice. Fiber photometry is a technique that uses a tiny fiber optic cable to detect brain activity in live animals by measuring light signals from neurons in real time. To achieve this, neurons of interest are first genetically modified to produce the needed light signal when active.
Mice were first exposed to chronic stress to make them display symptoms similar to those found in depressed humans. The most important of these symptoms for this study was a reduced response to rewards—sugar, in this case. Study authors examined how this response changed after giving mice a single dose of citalopram and what happened after continued use. They also used a drug called (S)-WAY100135 dihydrochloride, which blocks a specific type of serotonin receptor in the brain (5-HT1A receptors), to see how the effects of the antidepressant would change after that.
Results showed that, after a single dose of citalopram, neural response in the dorsal raphe nucleus to sugar (i.e., reward) was decreased. In other words, instead of becoming more sensitive to rewarding experiences (due to increased serotonin levels), mice became less sensitive. It turned out that the first dose of citalopram increases the amount of serotonin in the brain. However, it also triggers an autoinhibitory reaction that initially suppresses the antidepressant effects. With continued intake of citalopram, the brain adapts, and the autoinhibition effect gradually decreases, allowing the antidepressant effects of citalopram to become more visible.
Further investigation showed that this initial suppression of neural activity is achieved through 5-HT1A receptors (a type of serotonin receptor). When the study authors injected mice with (S)-WAY100135, a drug that blocks 5-HT1A receptors, the suppression of neural activity caused by the first dose of citalopram disappeared.
“By using the fiber photometry technique in free-moving animals, this study demonstrated that acute SSRI treatment reduces sucrose licking-induced activation of DRN [dorsal raphe nucleus] serotonin neurons via 5-HT1A autoreceptors, and co-treatment with SSRIs and 5-HT1AR antagonists partly mimic the effects of chronic SSRI treatment within a shorter timeframe,” the study authors concluded.
The study sheds light on the biochemical mechanisms of citalopram’s antidepressant effects. However, it should be noted that this was a study on mice, not on humans. While mice and humans share many physiological similarities, they are still very different species. Effects on humans might not be identical.
The paper, “(https://doi.org/10.1016/j.jphs.2025.01.001) Effect of antidepressants and social defeat stress on the activity of dorsal raphe serotonin neurons in free-moving animals,” was authored by Masashi Koda, Hiroyuki Kawai, Hisashi Shirakawa, Shuji Kaneko, and Kazuki Nagayasu.

(https://www.psypost.org/did-scientists-just-confirm-the-horseshoe-theory-of-politics-extremism-fuels-protest-across-ideological-lines/) Did scientists just confirm the horseshoe theory of politics? Extremism fuels protest across ideological lines
Mar 20th 2025, 08:00

People are more likely to take part in protests and other forms of collective action when the cause aligns with their political values. However, new research suggests that political extremism itself—regardless of ideology—also drives activism. A study published in (https://onlinelibrary.wiley.com/doi/10.1111/pops.70008) Political Psychology found that individuals with extreme political beliefs, whether on the left or the right, are more likely to engage in collective action, even if the movement does not align with their ideology. The findings suggest that emotions, particularly anger, play a central role in this relationship.
“Both societal and fundamental interests inspired this research. At the societal level, there is a longstanding debate about the role of political extremes in social movements. In France, this question became particularly salient during the Yellow Vest movement, with analysts attempting to categorize the movement as left-wing, right-wing, or simply extreme,” explained (https://www.researchgate.net/profile/Gaelle-Marinthe) Gaëlle Marinthe, an associate professor at Clermont Auvergne University.
“On the fundamental side, I am deeply interested in the similarities and differences between groups with ideologically opposing viewpoints. My colleagues and I wanted to examine the influence of both ideological values and a more cognitive feature of one’s ideological position (i.e., extremism) in political investment and, in this study, collective action. Our research is based on the premise that values and beliefs indeed play a major role in political behavior. However, structural features of ideology or belief (and in this case, extremism) may operate similarly across different ideological groups and may sometimes lead to counterintuitive outcomes—potentially even undermining the group’s long-term objectives.”
The researchers hypothesized an asymmetric U-shaped relationship between political ideology and activism. This means those at the far ends of the political spectrum—on either the left or the right—are more likely to participate in activism. The researchers also examined the role of emotions, particularly anger, fear, and hope, to understand how they influence the relationship between ideology, extremism, and activism. To examine this, they conducted two studies.
The first study focused on a real-world protest movement in France that opposed government-imposed COVID-19 restrictions. This movement was largely aligned with right-wing values, emphasizing personal freedoms and skepticism toward government interventions.
A total of 1,386 participants completed surveys during the protests. Participants reported their political ideology on a scale from left to right and were also assessed for political extremism, meaning how strongly they identified with the far ends of the spectrum. The researchers measured their intentions to participate in the protests and their levels of anger, fear, and hope.
The results supported the researchers’ hypothesis. As expected, those with right-wing political views were more likely to express intentions to participate in the protests. However, political extremism, whether right-wing or left-wing, was also associated with a greater likelihood of joining the protests. This confirms the asymmetric U-shaped relationship—those at the ideological extremes were more likely to engage in collective action, even if they did not completely align with the movement’s specific values.
Anger played a significant role in explaining this effect. Political extremism was linked to higher levels of anger, which in turn increased people’s willingness to participate in protests. Fear and hope had less consistent effects. Right-wing ideology was associated with lower levels of fear, which further encouraged participation. Meanwhile, higher levels of political extremism were linked to lower levels of hope, but the role of hope in motivating activism was unclear.
To see if these findings would hold in a left-wing movement, the researchers conducted a second study focused on protests against pension reform in France. This movement was largely supported by left-wing individuals who opposed the government’s plans to raise the retirement age.
A total of 418 participants completed surveys during the protests. The study measured the same variables as in Study 1, including political ideology, political extremism, anger, fear, hope, and both intentions and actual participation in collective action.
The findings mirrored those of the first study. Left-wing ideology was strongly associated with participation in the pension reform protests. However, political extremism, regardless of whether it was left-wing or right-wing, was also linked to higher levels of engagement. This again confirmed the asymmetric U-shaped relationship between ideology and collective action.
Anger once again played a central role. Both political ideology and political extremism were associated with higher levels of anger, which in turn increased participation in protests. However, fear showed a different pattern compared to Study 1. While right-wing individuals showed less fear in Study 1, left-wing individuals in Study 2 reported higher levels of fear, and fear was unexpectedly linked to greater intentions to participate in the pension reform protests.
“We examined two real-life social movements in France: one advocating right-wing values (opposing COVID-19 restrictions) and one supporting left-wing values (protesting pension reform),” Marinthe told PsyPost. “Our findings revealed an asymmetrical U-shaped relationship between political ideology and collective action.”
“In other words, people engage in collective action that aligns with their ideology (left or right), but those at the political extremes are also more likely to participate in collective action, even when it does not align with their ideological values. This is partly (but not solely) driven by heightened anger at both extremes of the political spectrum, which can fuel activism.”
“Beyond anger, we also explored the roles of fear and hope, but our results were inconsistent,” Marinthe explained. “This suggests that the impact of these emotions is more complex than we initially expected. Based on these inconsistencies, we speculate that fear and hope may have contradictory relationships with both political ideology and collective action, depending on how they are framed.”
The findings are in line with the horseshoe theory of politics, a political concept that suggests the far-left and the far-right, rather than being at opposite ends of a straight ideological spectrum, actually resemble the two ends of a horseshoe—curving toward each other and sharing certain similarities despite their apparent differences.
The study’s findings show that extremism itself, rather than just ideological content, plays a key role in mobilizing people for collective action. Whether protesting COVID-19 restrictions or pension reform, extremists were more likely to take part, driven by strong emotional responses. This suggests that beyond traditional left-right divides, political engagement at the extremes may be fueled by similar psychological tendencies.
However, it is important to note the study does not suggest that extreme leftists and extreme rightists are ideologically similar or that they frequently participate in each other’s movements. While both extremes show heightened engagement, they still tend to mobilize for causes that at least partially align with their values. The findings suggest that political extremism fuels activism across ideological lines, but they do not necessarily indicate that far-left and far-right politics “meet” in terms of ideology.
The findings are also based on two specific protest movements in France. France has a strong tradition of public demonstrations, and the results might not generalize to other countries where protesting is less common or carries greater risks. “Since our studies were conducted in France, replication in other countries is necessary to assess the generalizability of our results,” Marinthe said.
Additionally, both studies focused on anti-government protests. It is possible that political extremism is particularly relevant for activism that opposes those in power. Future research could examine whether political extremism also predicts participation in movements that support government policies or advocate for broader social changes.
“This research aligns with my broader interest in group and political dynamics,” Marinthe said, “particularly in understanding: 1.) how groups with divergent objectives may function in similar ways and 2.) how groups sometimes act or make decisions in ways that counter their primary interests or could be detrimental in the long run.”
“I would like to emphasize that this research, as well as other studies we conduct, does not equate different groups in terms of their values or impact,” she added. “Our goal is to understand political and group dynamics that may operate similarly across groups with drastically different objectives.”
The study, “(http://dx.doi.org/10.1111/pops.70008) Collective action among the extremes? Relations between political ideology, political extremism, emotions, and collective action,” was authored by Gaëlle Marinthe, Alice Kasper, Romain Veillé, and Fanny Lalot.

(https://www.psypost.org/defecation-and-cognitive-function-a-surprising-link-discovered-in-elite-triathletes/) Defecation and cognitive function: A surprising link discovered in elite triathletes
Mar 20th 2025, 06:00

A new study published in (https://doi.org/10.1016/j.smhs.2024.04.001) Sports Medicine and Health Science suggests that defecation may improve cognitive performance in elite athletes. Researchers found that participants completed a demanding cognitive task, the Stroop test, more quickly after defecation than when they had not defecated. Magnesium supplementation, which aids bowel movements, further enhanced performance.
The motivation for this study arose from an unexpected observation in a previous experiment. While conducting a PET scan to measure glucose metabolism across the body, researchers noticed that a region near the rectum displayed glucose uptake levels comparable to those in the brain.
They suspected the signal was an artifact caused by glucose accumulation in the bladder. However, three-dimensional PET imaging confirmed that this highly active area was distinct from the digestive tract. Given that glucose is the primary energy source for neural activity, the discovery raised an intriguing possibility: Could this region play a role in cognitive function?
This question gained further support from clinical observations. Studies have linked constipation to impaired executive function in dementia patients, suggesting that rectal health might influence cognitive performance. Additionally, historical theories propose that the enteric nervous system—a network of neurons embedded in the gut—could function as a “first brain” that evolved before the central nervous system.
“Many years ago, we conducted a PET scan to measure relative glucose uptake across the human body. Unexpectedly, we observed that the subnavel region exhibited glucose uptake similar to that of the brain (highest in the body),” explained study author Chia-Hua Kuo, a professor at the University of Taipei. “To investigate further, we hypothesized that manipulating pressure in this region might influence cognitive processes, particularly judgment-based decision-making tasks and exercise performance.”
Thirteen elite college-aged triathletes participated in a randomized crossover trial with three conditions: non-defecation, voluntary defecation without supplementation, and defecation after magnesium intake. The study design included a one-week washout period between each condition to prevent residual effects. Participants followed a controlled diet and fasted overnight before each session to minimize dietary influence. Testing was conducted in the morning, with all participants urinating upon waking and consuming a fixed amount of water before defecation.
To assess cognitive function, the researchers used the Stroop test, a widely recognized measure of executive function. This test requires participants to quickly identify the color of printed words, even when the word itself represents a different color (e.g., the word “red” printed in blue ink). The test challenges selective attention and cognitive flexibility, with faster completion times indicating better performance.
To examine physiological changes, the researchers measured blood distribution and oxygenation levels using near-infrared spectroscopy (NIRS). Sensors were placed on both the prefrontal brain, a region associated with executive function, and the sub-navel region, where the highest glucose uptake had been observed in previous PET scans. By comparing changes in blood flow and oxygen consumption during the Stroop test, the researchers aimed to determine whether defecation influenced cognitive function through physiological mechanisms.
The researchers found evidence that defecation improved cognitive performance. Participants completed the Stroop test more quickly after defecating compared to when they had not. On average, completion times were 27.1 seconds in the non-defecation condition, 24.4 seconds after voluntary defecation, and 23.4 seconds after magnesium-induced defecation. Every participant performed better after magnesium supplementation, and the majority (69%) performed better after non-supplemented defecation. This suggests that rectal emptying alone contributes to improved cognitive performance, with magnesium potentially enhancing the effect.
“Our findings suggest that the rectal region plays an unexpected role in rapid decision-making,” Kuo told PsyPost. “Reducing pressure in this area may enhance cognitive judgment, potentially offering practical applications for mental performance.”
Physiological measurements provided further insights. Despite no significant changes in blood distribution to the prefrontal brain, oxygen levels in the sub-navel region decreased after defecation, indicating increased oxygen consumption in this area during the cognitive task. This pattern suggests that this lower abdominal region may play an active role in rapid cognitive processing.
“We found that defecation increases oxygen consumption in the subnavel region during judgment tasks, indicating a possible link between gastrointestinal activity and cognitive function,” Kuo said.
The results challenge traditional assumptions about cognition being solely centered in the brain. The gut’s enteric nervous system, often called the “second brain,” contains extensive neural networks that communicate with the central nervous system. The findings of this study imply that rectal activity might influence cognitive efficiency, potentially explaining why sensations in this region—often described as “gut feelings”—are linked to instinctual decision-making.
But there are limitations to consider. The sample size was relatively small, consisting only of 13 elite triathletes. Future research should examine whether similar effects occur in different populations, including non-athletes, older adults, and individuals with gastrointestinal disorders.
Additionally, the study did not explore the long-term effects of magnesium supplementation or whether regular bowel habits influence sustained cognitive performance. Further research is needed to determine whether other factors, such as microbiota composition or gut motility, contribute to the observed effects.
The findings also raise questions about the broader role of the enteric nervous system in cognition. The high glucose uptake and increased oxygen consumption in the sub-navel region suggest that this area may serve a previously unrecognized function in rapid decision-making. Future studies using neuroimaging techniques could investigate whether neural activity in this region correlates with specific cognitive processes.
The researchers are now investigating alternative methods of inducing defecation to further understand the relationship between rectal activity and cognitive function. “We are currently exploring the effects of glycerin-induced defecation to further investigate this phenomenon,” Kuo said.
The study, “(https://doi.org/10.1016/j.smhs.2024.04.001) Defecation after magnesium supplementation enhances cognitive performance in triathletes,” was authored by Chen-Chan Wei, M. Brennan Harris, Mengxin Ye, Andrew Nicholls, Ahmad Alkhatib, Luthfia Dewi, Chih-Yang Huang, and Chia-Hua Kuo.

(https://www.psypost.org/mental-health-challenges-surged-among-children-and-adolescents-during-the-covid-19-pandemic-new-study-finds/) Mental disorders surged among children and teens during COVID-19 pandemic, new study finds
Mar 19th 2025, 20:00

A new study analyzing global mental health data has revealed a sharp increase in mental disorders among children and adolescents during the COVID-19 pandemic. The study, published in (https://www.cambridge.org/core/journals/psychological-medicine/article/global-burden-of-mental-disorders-in-children-and-adolescents-before-and-during-the-covid19-pandemic-evidence-from-the-global-burden-of-disease-study-2021/430C2B921A1C32D284EE040F08A1D3BB) Psychological Medicine, found that the number of new mental disorder cases among individuals aged 5 to 24 increased by more than 11% annually during this period. The findings highlight the pandemic’s lasting impact on youth mental health.
The mental health of young people has long been a public health concern, with many disorders first appearing during childhood and adolescence. Mental disorders can affect cognitive development, school performance, relationships, and overall well-being, often carrying long-term consequences into adulthood. The COVID-19 pandemic created a new set of challenges that disrupted daily life, education, and social interactions, all of which are known to influence mental health.
Although previous research has examined the effects of the pandemic on mental health, there has been a lack of large-scale, globally representative studies specifically focused on children and adolescents. The authors of the new study sought to address this gap by using data from (https://ghdx.healthdata.org/gbd-2021) the Global Burden of Diseases Study 2021. They aimed to quantify changes in the prevalence and burden of mental disorders before and during the pandemic, providing a clearer picture of how young people were affected worldwide.
The researchers analyzed mental health data from 204 countries and territories, focusing on individuals aged 5 to 24. They examined three key measures: the number of new cases, the total number of people affected (prevalence), and the burden of mental disorders in terms of years lived with disability (YLDs). They compared data from 2019, before the pandemic, to data from 2020 and 2021, during the height of the pandemic’s disruptions.
To estimate how much of the increase in mental disorders was directly related to the pandemic, researchers used a statistical model called a Bayesian age–period–cohort model. This allowed them to predict what mental disorder rates would have been in 2020 and 2021 based on pre-pandemic trends. The difference between these estimates and the actual recorded data provided an estimate of the additional burden associated with the pandemic.
The researchers also examined how these trends varied by sex, age group, and socioeconomic development, using a measure called the sociodemographic index. This index takes into account education levels, income, and fertility rates to assess how a country’s level of development might be linked to changes in mental health.
The results showed a significant increase in mental disorders among children and adolescents during the pandemic. In 2021 alone, there were an estimated 123 million new cases of mental disorders in this age group. The overall rate of new cases increased by 11.8% per year during the pandemic, a sharp rise compared to pre-pandemic trends.
Anxiety disorders saw the most dramatic shift, becoming the leading cause of nonfatal disability in this age group, with 12.9 million years lived with disability recorded in 2021. Depressive disorders also saw a rise, moving up to the fourth leading cause of disability. Both anxiety and depression showed substantial increases in their prevalence and impact.
The study also revealed disparities based on sex and age. Females experienced a greater rise in mental disorders than males, particularly in terms of depression. Young adults aged 15 to 24 were most affected, with the largest increases in both anxiety and depression occurring in this group. Children under 10 also saw notable increases in anxiety, highlighting that even younger age groups were not spared from the pandemic’s mental health toll.
Geographically, the increase in mental disorders was more pronounced in wealthier regions with higher levels of economic development. The study found a significant positive correlation between the additional burden of mental disorders and a country’s sociodemographic index. High-income regions such as North America, Western Europe, and Australasia saw some of the largest increases in anxiety and depression rates. Some regions in Latin America also experienced particularly sharp rises.
As with all research, there are some limitations to take into account. The quality of mental health data varies by country, with some lower-income regions lacking detailed records. Additionally, the study relied on statistical models to estimate the expected mental health burden in the absence of the pandemic, which may not fully capture the complexity of mental health trends.
Another limitation is the study’s inability to account for racial and ethnic differences in mental health outcomes, as the dataset did not include information on these factors. Future research could explore how racial and cultural differences influence mental health responses to global crises.
Additionally, the study used data only through 2021, meaning it does not capture the full post-pandemic picture. More research is needed to understand whether these mental health effects are temporary or if they will have lasting consequences. Long-term studies will be necessary to track recovery and identify ongoing challenges.
The study, “(https://doi.org/10.1017/S0033291725000649) Global burden of mental disorders in children and adolescents before and during the COVID-19 pandemic: Evidence from the Global Burden of Disease Study 2021,” was authored by Yubo Liu, Yijun Ren, Chenxi Liu, Xiaoli Chen, Danlei Li, Jia Peng, Liao Tan, and Qilin Ma.

(https://www.psypost.org/ketamine-shows-promise-for-treatment-resistant-ptsd-in-psychedelic-style-therapy-settings/) Ketamine shows promise for treatment-resistant PTSD in psychedelic-style therapy settings
Mar 19th 2025, 16:00

A new study published in the (https://doi.org/10.1177/02698811241286726) Journal of Psychopharmacology suggests that intravenous ketamine, when administered in a setting that mirrors psychedelic-assisted therapy, can lead to substantial and sustained reductions in symptoms of post-traumatic stress disorder (PTSD). Researchers analyzed records from 117 patients with treatment-resistant PTSD and found that the majority experienced meaningful improvement, with over 60% reaching remission. The findings highlight the potential of ketamine in therapeutic environments that emphasize preparation, integration, and sensory immersion.
PTSD is a mental health condition that can develop after a person experiences or witnesses a traumatic event. People with PTSD often suffer from intrusive memories, flashbacks, avoidance of reminders, negative shifts in mood and thinking, and heightened states of anxiety or arousal. The disorder affects millions worldwide and is particularly prevalent among military veterans, first responders, and survivors of violence or disaster.
Traditional PTSD treatments include therapy and medications, but these options are not always effective. Talk therapies such as cognitive-behavioral therapy can take time and may not work for everyone. Medications, particularly antidepressants, help some patients but can have side effects and take weeks to show results. Many individuals with PTSD struggle with treatment resistance, meaning that conventional approaches do not significantly alleviate their symptoms.
In recent years, researchers have explored alternative treatments that work more quickly and effectively for those who do not respond to traditional methods. Ketamine, originally used as an anesthetic, has gained attention for its fast-acting antidepressant effects and potential to treat other mental health conditions, including PTSD. Some studies have shown promising results, but others have been inconclusive. This inconsistency has led researchers to investigate whether the way ketamine is administered—particularly in settings that support psychedelic experiences—could influence its effectiveness.
To explore the effects of ketamine in a more supportive setting, researchers examined data from 117 patients receiving treatment at a New York City clinic specializing in psychedelic-assisted therapies. The clinic’s approach involved multiple components designed to enhance the therapeutic experience. Patients participated in preparatory discussions before ketamine infusions, which helped them set intentions for their treatment. During infusions, they wore eye masks and listened to evocative music, reducing external distractions and encouraging introspection. After treatment sessions, they engaged in integration discussions to process their experiences.
Patients received an average of nearly five intravenous ketamine infusions, with doses adjusted to achieve a psychedelic-level effect. The study included only individuals with PTSD symptoms above a certain severity threshold, ensuring that the results applied to those with significant distress. The researchers measured PTSD symptoms before and after treatment using the PTSD Checklist for DSM-5 (PCL-5), a widely used assessment tool.
The results showed that ketamine treatment in this supportive environment led to major improvements in PTSD symptoms. At the beginning of treatment, the average PCL-5 score was 52.54, indicating significant distress. By the end of treatment, the average score had dropped to 28.78. This reduction represents a large effect size, meaning the improvements were not just statistically significant but also meaningful in a real-world sense.
Among the 117 patients analyzed, 75% showed a clinically significant reduction in symptoms, and 62% achieved remission, meaning their symptoms dropped below the threshold for a PTSD diagnosis. These improvements were seen across a wide range of follow-up periods, with some patients showing benefits within two weeks and others maintaining gains for months.
Notably, the study found that patients who received additional psychotherapy alongside ketamine treatment had even better outcomes. Those who engaged in therapy had a greater reduction in PTSD symptoms compared to those who only received ketamine. This finding suggests that ketamine may be most effective when combined with psychological support.
While the study’s findings are encouraging, there are limitations to consider. The study was observational, meaning it did not include a control group receiving a placebo or another form of treatment for comparison. Without a placebo group, it is difficult to determine how much of the improvement was due to ketamine itself versus other factors, such as the therapeutic environment, expectations of benefit, or natural symptom fluctuations.
Another limitation is that follow-up periods varied widely among patients, making it challenging to assess the long-term durability of the effects. Additionally, the study sample was not fully representative of the broader PTSD population, as most participants were women, and nearly half did not report their racial or ethnic background.
Future studies should use randomized controlled designs to confirm these findings and compare ketamine to other emerging treatments, such as MDMA-assisted therapy. Researchers could also investigate the specific components of the psychedelic-inspired treatment environment that contribute most to the observed improvements. Understanding these factors could help refine ketamine therapy protocols and maximize its effectiveness for PTSD.
The study, “(https://doi.org/10.1177/02698811241286726) Rapid and sustained reduction of treatment-resistant PTSD symptoms after intravenous ketamine in a real-world, psychedelic paradigm,” was authored by Henry A. MacConnel, Mitch Earleywine, and Steven Radowitz.

(https://www.psypost.org/brain-scans-reveal-how-drum-and-bass-influence-music-perception/) Brain scans reveal how drum and bass influence music perception
Mar 19th 2025, 14:00

A new study published in (https://doi.org/10.1016/j.neuroscience.2024.10.024) Neuroscience sheds light on how drum and bass components influence the brain’s response to pop music. Researchers found that when drum and bass elements were removed from a song, brain activity increased in areas linked to auditory processing and cognitive effort. Meanwhile, when participants listened only to drum and bass without vocals or other instruments, their brains showed heightened activity in regions associated with movement and rhythm perception. These findings suggest that drum and bass play a fundamental role in shaping the way listeners experience and interpret music.
In pop music, drum and bass elements form the rhythmic foundation that helps listeners perceive and engage with the beat. Drums establish a predictable framework of beats, while bass lines reinforce the harmonic structure of the song. These elements work together to create a metrical structure that makes it easier for listeners to follow the rhythm and, in many cases, feel compelled to move along with the music.
Previous research has demonstrated that rhythmic complexity influences brain activity, particularly in regions associated with movement and reward processing. However, most studies have focused on isolated drum patterns or melodies, rather than the full, layered compositions found in real-world music. This study aimed to address that gap by examining how the brain responds when drum and bass components are removed or isolated in full musical excerpts.
The researchers recruited 25 participants between the ages of 20 and 29, all of whom were Mandarin pop music listeners with no formal knowledge of the Korean language. This ensured that they were unfamiliar with the Korean pop music excerpts used in the experiment. Participants underwent functional magnetic resonance imaging (fMRI) scans while listening to different versions of 18 Korean pop songs.
To isolate the effects of drum and bass, the researchers used artificial intelligence-based algorithms to create three versions of each song excerpt:

Whole Music Version – included all instrumental and vocal components.
Drum & Bass Version – contained only the drum and bass, with vocals and other instruments removed.
Vocals & Others Version – included vocals and other instruments, but excluded drum and bass.

Each participant listened to all three versions of each excerpt while their brain activity was recorded. They were also asked to rate their preference for each version, though they were not explicitly asked to evaluate rhythm perception or movement sensation.
The brain imaging results revealed distinct patterns of neural activity depending on which version of the music participants heard.
When participants listened to the Vocals & Others Version, brain activity increased in regions associated with cognitive effort, including the auditory dorsal pathway. This pathway plays a key role in rhythm processing, particularly when listeners need to infer the beat in the absence of clear rhythmic cues. The heightened activation in this condition suggests that when drum and bass were removed, the brain had to work harder to process the timing and structure of the music.
In contrast, the Drum & Bass Version elicited increased activation in brain regions associated with movement simulation, particularly in the right ventral premotor cortex and the left dorsolateral prefrontal cortex. These areas are involved in motor planning and have been linked to the brain’s mirror neuron system, which helps people anticipate and synchronize their movements with rhythmic patterns. This suggests that drum and bass alone can trigger neural activity related to movement, even when listeners are unable to physically respond.
Interestingly, the Whole Music Version did not produce significantly different activation patterns compared to the other two versions. This indicates that the presence or absence of drum and bass has a stronger effect on brain activity than simply listening to a full song.
The study highlights the fundamental role of drum and bass in shaping how the brain processes pop music. But there are some limitations to consider. First, because participants were not asked to evaluate their urge to move, the study does not directly measure groove sensation—the feeling of wanting to dance or tap along with the beat. Future studies could include more direct assessments of movement intention and physical responses.
The study, “(https://doi.org/10.1016/j.neuroscience.2024.10.024) The presence of drum and bass modulates responses in the auditory dorsal pathway and mirror-related regions to pop songs,” was authored by Chia-Wei Li and Chen-Gia Tsai.

(https://www.psypost.org/vagus-nerve-stimulation-changes-brain-chemistry-hinting-at-therapeutic-potential/) Vagus nerve stimulation changes brain chemistry, hinting at therapeutic potential
Mar 19th 2025, 12:00

A recent study published in (https://doi.org/10.1111/psyp.14709) Psychophysiology provides new insights into how stimulating the vagus nerve through the ear might influence brain function. Researchers found that a single 30-minute session of transcutaneous auricular vagus nerve stimulation (taVNS) led to notable reductions in a specific protein associated with synaptic activity in rats. This change was observed in key brain areas linked to cognition, motor control, and mood regulation.
However, the study did not find changes in glucose metabolism, a marker of overall brain activity. These findings contribute to the growing body of research suggesting that non-invasive vagus nerve stimulation could have therapeutic potential for neurological and psychiatric disorders.
The vagus nerve is a critical part of the nervous system that connects the brain to various organs, including the heart, lungs, and digestive tract. It plays an essential role in regulating bodily functions such as heart rate, digestion, and inflammation. Because of its widespread influence, researchers have been investigating how electrical stimulation of this nerve might help treat conditions such as epilepsy, depression, and chronic pain. Traditional vagus nerve stimulation (VNS) involves implanting a device that delivers electrical impulses directly to the nerve. While effective, this method requires surgery and carries risks of complications.
More recently, scientists have been exploring a less invasive alternative: transcutaneous auricular vagus nerve stimulation (taVNS). This method uses electrodes placed on the skin of the ear, an area connected to a branch of the vagus nerve. Early studies suggest that taVNS may provide similar benefits to implanted VNS but without the need for surgery. However, the mechanisms behind taVNS remain unclear. To better understand its effects on the brain, the researchers in this study used a combination of advanced imaging techniques and animal models.
“We have studied brain stimulation modalities in animal models in our lab for several years and have looked at the effects on brain neurotransmission using PET imaging in an attempt to unravel the therapeutic mechanisms relevant to diseases like depression and Parkinson’s disease,” explained postdoctoral researcher (https://www.au.dk/en/karina.binda@clin.au.dk) Karina Binda and Associate Professor (https://www.au.dk/en/alandau@clin.au.dk) Anne Landau of the Translational Neuropsychiatry Unit at Aarhus University.
“Transcutaneous auricular vagus nerve stimulation (taVNS), which has shown some potential as a treatment for neurological disorders, became particularly interesting to us since the current is administered via an ear clip, making it non-invasive with no requirement for surgery or electrode implant.”
The researchers worked with 24 female Sprague–Dawley rats, a commonly used laboratory species. They divided the rats into two groups: one received real taVNS, while the other underwent a sham treatment where electrical stimulation was applied to a different part of the body (the foot) as a control measure. The stimulation lasted 30 minutes, targeting the left ear in the taVNS group.
To measure changes in brain activity, the researchers used two types of positron emission tomography (PET) imaging. One technique used a tracer called [11C]UCB-J to assess levels of synaptic vesicle glycoprotein 2A (SV2A), a protein found in presynaptic nerve terminals that plays a role in neurotransmitter release. Higher SV2A levels typically indicate more active synaptic connections. The other technique used [18F]fluorodeoxyglucose ([18F]FDG) to measure glucose metabolism, a standard marker of overall brain activity.
Each rat underwent imaging twice—once before stimulation (baseline) and once after. By comparing the two sets of images, the researchers were able to assess the impact of taVNS on brain function.
“Given the potential therapeutic utility of taVNS, we conducted a small brain imaging study in healthy rats where we aimed to determine the short-term effects of a single taVNS,” the researchers explained. “We used microPET, an approach that relies on the administration of radioactive-labeled molecules to study specific changes in the living brain and investigated brain glucose metabolism and how synaptic connections change in response to taVNS.”
The main finding was that taVNS led to significant reductions in SV2A levels in several brain regions, including the frontal cortex, striatum, and midbrain. These reductions ranged from 36% to 59%, suggesting that taVNS affects synaptic function in multiple areas of the brain. Importantly, the decrease in SV2A was observed on both sides of the brain, even though stimulation was applied only to the left ear. This suggests that taVNS has widespread effects on neural activity rather than being limited to the directly stimulated area.
“The bilateral reduction in our measure of synaptic density binding was surprising, despite the stimulation being unilateral, which suggests a more widespread initial effect than had been originally anticipated,” Binda and Landau told PsyPost.
In contrast, the study found no significant changes in glucose metabolism. This result suggests that while taVNS may influence synaptic activity, it does not cause broad shifts in overall energy use in the brain—at least not in the short term.
“It was also intriguing that these changes in our synaptic marker occurred without significant alterations in brain glucose metabolism, suggesting that taVNS may acutely influence neurotransmitter systems rather than overall metabolic activity,” the researchers said. “However, it is possible that the effects of chronic taVNS will induce different effects, and this needs to be explored in future studies.”
These findings provide new insights into how taVNS might work at the molecular level. The observed reduction in SV2A levels could indicate that taVNS influences neurotransmitter release, potentially altering communication between brain cells. Given that synaptic dysfunction is implicated in various neurological and psychiatric disorders, these changes could be relevant for understanding how taVNS might exert therapeutic effects.
“Our preliminary findings suggest that even a single administration of taVNS can modulate brain function at the synaptic level, which could have implications for treating neurological and psychiatric disorders,” Binda and Landau explained. “This should be seen as a starting point for future studies, where the mechanisms of taVNS are explored in the living brain.”
One important limitation is the small sample size, which means the findings need to be confirmed in larger studies. Additionally, the study only included female rats, so it is unclear whether the results would be the same in males. Future research should explore whether sex differences influence the effects of taVNS.
Another limitation is that the study only looked at the immediate effects of a single session of taVNS. It is possible that repeated or long-term stimulation could lead to different or more pronounced effects on brain function. Future studies could investigate whether chronic taVNS produces lasting changes in synaptic activity and whether these changes translate into behavioral or cognitive improvements.
Finally, while the study focused on synaptic density and glucose metabolism, other biological markers may also be relevant. Future research could examine whether taVNS influences inflammation, neurotransmitter levels, or other aspects of brain function.
“In the field of brain stimulation and neuroimaging, we are currently studying changes in the binding of our synaptic density PET marker in a minipig model of Parkinson’s disease in response to acute and chronic deep brain stimulation,” Binda and Landau said.
“In the context of non-invasive brain stimulation, our goal is to investigate the effects of both acute and chronic taVNS in preclinical disease models, particularly for conditions like Parkinson’s disease and depression where modulation of synaptic density could be beneficial. We aim to provide more robust preclinical data on the mechanisms of taVNS that can pave the way for its use as a therapeutic intervention for central nervous system disorders.”
The study, “(https://doi.org/10.1111/psyp.14709) Acute transcutaneous auricular vagus nerve stimulation modulates presynaptic SV2A density in healthy rat brain: An in vivo microPET study,” was authored by Karina H. Binda, Caroline C. Real, Mette T. Simonsen, Ebbe K. Grove, Dirk Bender, Albert Gjedde, David J. Brooks, Anne M. Landau.

Forwarded by:
Michael Reeder LCPC
Baltimore, MD

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