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(https://www.psypost.org/scientists-pinpoint-memory-related-neurons-that-drive-eating-behavior/) Scientists pinpoint memory-related neurons that drive eating behavior
May 5th 2025, 10:00

A new study published in Nature Metabolism has uncovered a surprising mechanism in the brain that helps explain why people may overeat, even when they’re not hungry. Researchers identified specific neurons in the hippocampus—a brain region known for memory—that store detailed information about the location and type of foods rich in fat and sugar. When activated, these neurons increase food consumption, while silencing them can prevent weight gain in mice. The findings suggest that memory, not just hunger or pleasure, plays a powerful role in driving what and how much we eat.
The research was led by (https://vagalafferant.com/) Guillaume de Lartigue, whose team set out to investigate how food-related memories influence dietary behavior. While scientists have long known that humans and animals can remember where to find palatable food, the direct role of memory circuits in overeating had not been clearly demonstrated. In modern environments where calorie-dense foods are readily available and food cues are constant, the researchers suspected that memory systems in the brain might be overactive and contributing to obesity.
The hippocampus is best known for its role in forming spatial and episodic memories—those tied to specific times, places, or experiences. Previous studies have hinted at its involvement in regulating food intake. For instance, lesions in this region increase eating and body weight in animals, and people with hippocampal damage may eat repeated meals without remembering the last one. The research team hypothesized that some hippocampal neurons might encode not just general satiety or hunger signals, but specific memories about fat or sugar consumption.
“We were interested in how memory influences eating behavior. While it’s well known that hunger and food pleasure drive eating, people often eat simply because an external cue (like the smell of fresh bread or the sight of a slice of cake) triggers the urge, even when they’re not hungry,” said de Lartigue, an associate professor at (https://monell.org/guillaume-de-lartigue/) Monell Chemical Senses Center and the Perelman School of Medicine at the University of Pennsylvania.
“Sometimes, just remembering that there’s a chocolate bar in your desk drawer can make you want to eat it. That led us to ask: can memory alone be enough to drive eating? And if so, how does the brain store and retrieve those food-related memories?”
To test this, the researchers used genetically modified mice that allowed them to “tag” active neurons in the dorsal hippocampus when the animals consumed fat or sugar. These neurons responded to post-ingestive nutrient signals delivered directly to the gut and were activated through a gut-brain communication pathway involving the vagus nerve. They found that fat and sugar each triggered a distinct group of neurons, and these two populations were largely non-overlapping. Fat-responsive neurons were concentrated in areas of the hippocampus associated with motivation, while sugar-responsive neurons were linked to spatial memory.
The researchers then manipulated these neurons in different ways. When they activated the sugar-responsive neurons, mice showed increased preference for and consumption of sugary solutions. Activation of fat-responsive neurons had a similar effect on fat intake. Conversely, silencing these neurons had the opposite outcome. Mice with deactivated sugar-memory neurons forgot where sugar was located, consumed less of it, and showed reduced weight gain—even when eating high-fat, high-sugar diets. Mice with silenced fat-memory neurons consumed less fat and showed less motivation to work for fatty rewards.
In further experiments, the team demonstrated that sugar-responsive neurons functioned like a “memory trace” for food location. When these neurons were stimulated, mice were better at remembering where they had previously found sugar. But when the neurons were removed, this spatial memory was impaired, and sugar consumption dropped. These effects were specific to food-related memories—general memory functions remained intact. Meanwhile, fat-responsive neurons appeared to enhance the motivational pull of fat. Silencing them reduced the animals’ willingness to expend effort for fat rewards, while stimulating them increased that motivation.
“What surprised us most was how specific these memories are. The brain doesn’t just store a general memory of food, it forms distinct memory traces for fat and sugar, using different sets of neurons. Even more surprising, these two groups of neurons affect behavior differently: sugar memories help the brain remember where to find sugar, while fat memories increase the motivation to go get it.”
In addition to influencing immediate food choices, these neurons also shaped long-term feeding behavior. Mice with deactivated sugar-memory neurons ate fewer meals during the inactive light phase of their day and resisted weight gain over several weeks, despite having unrestricted access to calorie-dense food. This pattern mimics some of the benefits of time-restricted eating, suggesting that impairing memory for food cues may help reduce snacking and prevent overeating.
“Our study shows that the brain not only remembers where high-calorie foods like sugar and fat were found, but that those memories can actually drive you to seek them out, even without hunger. We discovered specific neurons in the hippocampus (the brain’s memory center) that store these food memories, and when we activated or deleted them in mice, it changed how much and what they ate. In other words, memory itself can make you want to eat.”
The researchers argue that their findings open up new avenues for understanding and treating obesity. While much attention has focused on appetite hormones and reward pathways in the brain, this study highlights memory as a key driver of eating behavior. In environments where high-calorie food is easy to access and advertisements constantly remind us of past enjoyable meals, memory circuits may be overstimulated, encouraging people to eat even when they’re not hungry.
“Memory systems in the hippocampus evolved to help animals locate and remember food sources critical for survival,” said first author Mingxin Yang, a University of Pennsylvania doctoral student in the de Lartigue lab. “In modern environments, where food is abundant and cues are everywhere, these memory circuits may drive overeating, contributing to obesity.”
The study has some limitations. It was conducted in mice, and while the hippocampus performs similar functions in humans, more research is needed to confirm that these specific neuronal populations exist and operate the same way in people. Additionally, the researchers focused on isolated nutrients—sugar and fat—rather than real-world complex meals. This reductionist approach helps pinpoint mechanisms but may not capture the full complexity of human eating behavior.
Looking ahead, the researchers hope to investigate whether these memory-driven eating patterns can be modified or suppressed. If specific brain circuits that encode fat or sugar memories can be selectively turned down, it could lead to new strategies for reducing unhealthy eating habits. 
“We’re now exploring whether these memory-driven eating behaviors can be modified, which could open new doors for helping people who struggle with overeating or obesity. We are looking for ways of selectively increasing or decreasing the gain on the activity of these neurons to precisely influence what we eat.”
“One of the most exciting parts of this work is that it challenges the traditional view that only hunger, or pleasure, drive eating. We show that memory can be its own trigger, and that the hippocampus plays a central role in that process. It helps explain why we sometimes eat even when we don’t need to—and why high-calorie foods are especially hard to resist.”
The study, “Separate orexigenic hippocampal ensembles shape dietary choice by enhancing contextual memory and motivation,” was authored by Mingxin Yang, Arashdeep Singh, Alan de Araujo, Molly McDougle, Hillary Ellis, Léa Décarie-Spain, Scott E. Kanoski, and Guillaume de Lartigue.

(https://www.psypost.org/n-acetylcysteine-does-not-appear-to-be-effective-for-cannabis-use-disorder/) N-acetylcysteine does not appear to be effective for cannabis use disorder
May 4th 2025, 16:00

A recent study involving youth with cannabis use disorder found that N-acetylcysteine is not an effective treatment for the condition. After 12 weeks of treatment, there were no significant differences between the treatment and placebo groups in the proportion of negative urine cannabinoid tests or in self-reported cannabis use. The research was published in (https://doi.org/10.1038/s41386-025-02061-y) Neuropsychopharmacology.
Cannabis use disorder is a medical condition characterized by continued cannabis use despite experiencing significant impairment or distress. Individuals with this disorder often spend a considerable amount of time using cannabis and continue doing so even when it leads to problems at work, school, or in personal relationships. Long-term use in this manner may result in cognitive impairments, reduced motivation, and mental health issues such as anxiety or depression.
Over time, people with cannabis use disorder tend to develop a tolerance, requiring increasing amounts to achieve the same effect. If they abruptly stop using cannabis, they may experience withdrawal symptoms such as irritability, sleep disturbances, and changes in appetite.
Study author Kevin M. Gray and his colleagues aimed to evaluate the efficacy of N-acetylcysteine as a treatment for young people with cannabis use disorder. Participants received this treatment in conjunction with brief, clinician-delivered counseling and medical management of symptoms.
N-acetylcysteine is a supplement and medication derived from the amino acid cysteine. It is known for its antioxidant properties and its ability to replenish intracellular glutathione—a powerful antioxidant found in cells that helps protect them from oxidative stress and supports detoxification. Medically, N-acetylcysteine is used to treat paracetamol (acetaminophen) overdose and is being investigated for various other conditions, including respiratory illnesses, psychiatric disorders, and substance use disorders.
The study included 192 participants between the ages of 14 and 21 who were seeking treatment for cannabis use disorder. Of these, 140 completed the treatment period, and 93 completed follow-up assessments after treatment concluded.
Participants were randomly assigned to one of two groups. One group received 1200 mg of N-acetylcysteine per day (in the form of two 600 mg capsules), while the other group received identical-looking placebo capsules, both for a duration of 12 weeks.
Throughout the study, participants self-reported their cannabis use through daily mobile surveys. They also provided urine samples at the beginning of the study, during weekly visits, and at post-treatment follow-ups. Researchers used these urine samples to test for cannabinoids, providing an objective measure of cannabis use.
The results showed that participants who used cannabis more frequently before the study were less likely to maintain abstinence during the treatment period. Those who also smoked more tobacco were similarly less likely to remain abstinent. In contrast, participants who expressed greater readiness and confidence to quit were more likely to abstain from cannabis use during the study.
However, there were no significant differences in cannabis use between the N-acetylcysteine and placebo groups—either during treatment or after. This applied to both the proportion of negative urine cannabinoid tests and the participants’ self-reported cannabis use.
“Findings indicate that N-acetylcysteine is not efficacious for youth cannabis use disorder when not paired with contingency management, highlighting the potentially crucial role of a robust behavioral treatment platform in facilitating prior positive efficacy findings with N-acetylcysteine,” the study authors concluded.
This study adds to the growing body of research on N-acetylcysteine’s potential medical applications. However, the researchers acknowledged that the relatively high dropout rate—nearly 30 percent of participants did not complete treatment—may have influenced the results and should be considered when interpreting the findings.
The paper, “(https://doi.org/10.1038/s41386-025-02061-y) N-acetylcysteine for youth cannabis use disorder: randomized controlled trial main findings,” was authored by Kevin M. Gray, Rachel L. Tomko, Nathaniel L. Baker, Erin A. McClure, Aimee L. McRae-Clark, and Lindsay M. Squeglia.

(https://www.psypost.org/adhd-in-formerly-institutionalized-children-tied-to-slower-physical-and-brain-growth/) ADHD in formerly institutionalized children tied to slower physical and brain growth
May 4th 2025, 14:00

A new study published in the (https://doi.org/10.1111/jcpp.14110) Journal of Child Psychology and Psychiatry provides insight into how early-life institutional care affects physical and brain development—and how these developmental patterns are linked to attention-deficit/hyperactivity disorder (ADHD). Children who were raised in institutions before being placed in foster care showed delayed physical growth and changes in brain activity, particularly if foster placement occurred later in childhood. These delays were more pronounced in children who went on to develop ADHD, suggesting that prolonged adversity in early life may contribute to lasting differences in both body and brain development.
ADHD is a neurodevelopmental condition marked by persistent patterns of inattention, hyperactivity, and impulsivity. While it is common in the general population, the condition appears to be significantly more prevalent among children who have experienced early institutionalization. Past studies have already shown that children raised in institutional care are at greater risk of ADHD and physical growth delays, but it has remained unclear whether these outcomes share a common developmental pathway.
The present study aimed to explore that link using data from (https://www.bucharestearlyinterventionproject.org/) the Bucharest Early Intervention Project (BEIP)—a long-running randomized trial comparing outcomes among institutionalized children assigned either to foster care or to remain in institutional settings.
Researchers followed 177 children in Romania over the course of 16 years. Among them, 136 children had been raised in institutions. These children were randomly assigned either to continue with institutional care or to be placed in foster homes arranged by the study. A comparison group of 64 children who had never been institutionalized was also included. All participants were assessed multiple times from infancy to adolescence using physical growth measurements and electroencephalography (EEG), which tracks electrical activity in the brain. ADHD diagnoses were determined based on structured interviews with caregivers at two time points: at 54 months and again at age 12.
The results revealed a consistent pattern: children who remained in institutional care showed delayed physical growth and brain development, especially those who met criteria for ADHD. About 27% of institutionalized children were diagnosed with ADHD, compared to just 4.5% of children who had never been institutionalized. Among those placed into foster care, ADHD rates were significantly lower for children placed before the age of two, suggesting that early intervention plays a key role in reducing long-term developmental risks.
Physical growth data showed that children in institutional care were shorter, had smaller head circumferences, and weighed less than never-institutionalized children. Those placed in foster care did somewhat better, but only if they were placed at a younger age. Importantly, children with ADHD had even more delayed physical growth trajectories, particularly when it came to height and head circumference. Among children who were placed into foster care before age two, those with ADHD still showed slower growth than those without the disorder.
In terms of brain development, the study focused on two measures captured by EEG: peak alpha frequency and the theta-beta ratio. These are indicators of how the brain is maturing and organizing itself. Normally, peak alpha frequency increases with age, reflecting greater brain efficiency, while the theta-beta ratio tends to decrease as brain networks become more specialized. The researchers found that institutionalized children had slower increases in peak alpha frequency, especially those placed into foster care later in life. However, peak alpha frequency was not directly associated with ADHD diagnosis.
In contrast, the theta-beta ratio was significantly lower in children with ADHD, but only within the foster care group. This finding was unexpected, as elevated theta-beta ratios have often been associated with ADHD in other studies. The authors suggest that the lower ratio in these children may reflect unique developmental trajectories resulting from early adversity and subsequent intervention.
To investigate whether rapid physical growth after placement in foster care might negatively impact brain development—a theory known as the “maturational trade-off” hypothesis—the researchers used cross-lagged statistical models. These models allowed them to examine how changes in physical growth might influence brain activity over time, and vice versa. The results provided no support for the idea that faster physical growth comes at the expense of brain maturation. In fact, among children with ADHD, greater height at age 12 predicted more typical brain activity patterns at age 16.
This study adds to growing evidence that early childhood experiences—especially extreme deprivation—have lasting effects on both physical and neural development. While high-quality foster care can help mitigate some of these effects, the data suggest that children who go on to develop ADHD may not benefit as much from these interventions as others. The reasons for this are not entirely clear. One possibility is that ADHD itself may interfere with the ability to fully benefit from enriched environments. Another is that genetic factors contribute to both ADHD risk and the likelihood of early institutionalization, such as when biological parents struggle with mental illness or substance use.
The researchers acknowledge some limitations. The sample size was relatively small, which may have limited their ability to detect subtle effects. ADHD diagnoses were based on reports at only two time points, and about one-third of children had data from just one assessment. EEG methods changed partway through the study, which could have influenced results. In addition, the caregiving experiences of children in the foster care and institutional groups overlapped more than intended, due to placement disruptions and changes in living situations. Finally, the study could not account for genetic influences or prenatal exposures that might have affected development.
Despite these limitations, the study has several strengths. It is one of the only randomized controlled trials of foster care placement, allowing for stronger inferences about the effects of early environment on development. The use of repeated measures over time also enabled researchers to trace growth patterns across critical developmental periods.
The study, “(https://doi.org/10.1111/jcpp.14110) Physical and neurophysiological maturation associated with ADHD among previously institutionalized children: a randomized controlled trial,” was authored by Anne B. Arnett, Martín Antúnez, Charles Zeanah, Nathan A. Fox, and Charles A. Nelson.

(https://www.psypost.org/older-adults-reflect-less-on-their-personality-traits-than-younger-adults-study-finds/) Older adults reflect less on their personality traits than younger adults, study finds
May 4th 2025, 12:00

Older adults reflect less on their personality traits than younger adults, and people with lower emotional stability or extraversion tend to reflect more on these traits, according to new findings published in (https://doi.org/10.1080/15298868.2025.2477011) Self & Identity.
Self-reflection helps individuals understand their thoughts, feelings, and behaviors and plays a critical role in personality development. While personality traits evolve throughout life, this development slows with age. One proposed reason is that older adults may reflect less frequently on their behaviors and traits.
Previous research has examined general self-reflections, like philosophical musings or repetitive brooding, but has rarely focused on trait-specific reflections such as comparing oneself to others or to one’s past self. These specific reflections may better explain how personality changes over time, particularly for traits closely linked to mental health, such as extraversion and emotional stability.
Drawing on large lifespan samples from both Germany and the U.S., Gabriela Küchler and colleagues sought to clarify how people of different ages and personalities reflect on traits like extraversion and emotional stability, and how this behavior might support or inhibit personality development over time.
The researchers recruited a diverse sample of 615 adults from Germany (n = 313) and the United States (n = 304), between ages 18-84. Participants were recruited using Clickworker, an online crowdsourcing platform, and were required to be fluent in English or German, have computer access, and be at least 18 years old. The final sample was balanced across five age groups and genders, with quotas ensuring demographic heterogeneity.
General self-reflections were assessed using a validated scale that distinguished between explorative reflections (thoughtful, philosophical introspection) and ruminative reflections (negative, repetitive thinking). Trait-specific self-reflections focused on how often participants compared themselves to others or their past selves in terms of two personality traits, namely extraversion and emotional stability. These comparisons were measured using specific items tailored to capture social and temporal self-assessment. To assess personality, participants completed the Big Five Inventory-2, which measured levels of open-mindedness, emotional stability, and extraversion.
The researchers found that people who scored higher in open-mindedness reported engaging more in explorative self-reflection, suggesting that curiosity and a desire for self-understanding drive this form of introspection. Meanwhile, those with higher emotional stability, meaning those who experienced less anxiety and emotional volatility, reported lower levels of ruminative reflection, indicating they were less likely to dwell on negative experiences.
When it came to trait-specific reflections, individuals with lower levels of emotional stability or extraversion were more likely to compare themselves to others or to their past selves in these same traits. Interestingly, extraversion was linked primarily to social comparisons, whereas emotional stability was linked to both social and past-temporal comparisons.
Age also played a significant role in shaping self-reflection. Older adults were generally less likely to engage in both ruminative and trait-specific reflections, with these patterns holding even after accounting for their personality trait levels. However, the expected weakening of the link between personality traits and self-reflection with age did not hold.
In fact, in some cases, the associations grew stronger in older adults. For instance, older adults who were more extraverted were much less likely to compare themselves to their past selves than their less extraverted peers. Similarly, older adults who were emotionally stable were especially unlikely to compare themselves to others. These findings suggest that while younger adults may engage in more self-reflection overall, older adults’ reflection behaviors are more tightly linked to their actual personality traits.
This study only examined reflections related to two traits—extraversion and emotional stability—thus, the findings may not generalize to other personality traits.
The study, “(https://doi.org/10.1080/15298868.2025.2477011) Self-reflections across the adult lifespan: associations with personality traits in a binational sample,” was authored by Gabriela Küchler, Kira S. A. Borgdorf, Corina Aguilar-Raab, and Cornelia Wrzus.

Forwarded by:
Michael Reeder LCPC
Baltimore, MD

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