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. Author manuscript; available in PMC: 2026 Sep 14.
Published in final edited form as: Physiol Behav. 2025 Oct 21;303:115141. doi: 10.1016/j.physbeh.2025.115141

Obesity Suppresses Hippocampal Neurogenesis and Impairs Memory and Executive Function in a Weight and Sex-Specific Manner

Yasamin Baghdadchi 1, Carl White 2, Eugene Dimitrov 3
PMCID: PMC13571213  NIHMSID: NIHMS2201208  PMID: 41130433

Abstract

There is a well-established link between a high-fat diet (HFD) as a cause of obesity, which, in addition to metabolic and cardiovascular pathology, is also associated with memory loss and cognitive decline. We investigated the conditional relationship between HFD, body weight, cognitive performance and adult hippocampal neurogenesis in male and female mice. The mice receiving HFD for three months were heavier and exhibited impaired long-term memory and diminished problem-solving ability in comparison to the groups on standard chow diet (SD). The severity of the cognitive impairment was dependent on their weight as shown by regressive analysis of the data. However, the HFD and increased body weight negatively affected the short-term spatial memory, a hippocampus-dependent task, only in male but not in female mice. Next, we compared the expression of Ki67 and DCX as markers for adult neurogenesis in the subgranular zone of the dentate gyrus of the dorsal hippocampus of mice on SD and HFD. The HFD reduced the densities of Ki67- and DCX-labeled cells only in male but not in the female mice.

These results revealed that the cognitive impairment triggered by HFD was proportionate to the weight of the mice. However, the female mice preserved the rate of adult neurogenesis in the dentate gyrus and their cognitive functions in hippocampus-dependent tasks despite being susceptible to the deleterious effects of HFD in other cognitive domains.

Introduction

An increase in the consumption of food with a high caloric density that brings on obesity and impaired cardiovascular health is a worldwide phenomenon (Fung et al., 2001; Cordain et al., 2005). Compared to the other two macronutrients, carbohydrates and proteins, fatty foods provide much higher energy densities, and their overconsumption tips the energy balance of the body to energy excess and accumulation of body fat. Therefore, a sustained high-fat diet (HFD) leads to the development of metabolic syndrome, described as a constellation of central obesity, high blood pressure, insulin resistance and atherogenic dyslipidemia (Clifton, 2019). The basic pathophysiological mechanism underpinning all these symptoms is the increased blood levels of free fatty acids, which exert contra-insulin actions and trigger inflammatory response (Freeman et al., 2014). The inflammatory process develops not only in the vasculature and internal organs of the body but also advances into the CNS, where the high levels of free fatty acids cause the release of pro-inflammatory cytokines (Gomez-Apo et al., 2021). The persistent low-grade inflammation of the brain causes structural changes expressed as vascular injury and decreased cortical volume in the frontal and temporal lobes, very likely as a consequence of neuronal apoptosis (Beyer et al., 2019). Therefore, the decline of cognitive abilities associated with obesity is a direct result of neuroinflammation, vascular damage and neuronal loss (Beyer et al., 2019; Gomez-Apo et al., 2021). In humans, a cross-sectional study showed that increased body and visceral fat is associated with reduced cognitive scores independently of cardiovascular comorbidities (Anand et al., 2022). The hippocampus-dependent memory, attention and cognitive flexibility are the brain functions most severely affected by a lifelong diet high in fatty foods (Atak et al., 2023; Favieri, Forte and Casagrande, 2019; Yeomans et al., 2023).

The animal studies answer many of the intriguing questions about the mechanisms by which HFD negatively impacts brain processes. Rodents exposed to both long- and short-term HFD, along with increased body weight, develop some degree of metabolic alterations, such as high blood glucose and lipid levels (Park et al., 2010; Boitard et al., 2012) and cognitive impairment (Abbott et al., 2019; Evans et al., 2024; Lindqvist et al., 2006). Multiple studies have demonstrated that HFD increases inflammatory mediators in the hippocampus, suppresses adult neurogenesis (NG) and causes impairment of long- and short-term memory (Almeida-Suhett et al., 2017; Evans et al., 2024), for a comprehensive review see (Sharma, 2021). The HFD accelerates the aging process in the brain and the cognitive impairment associated with traumatic brain injury (Spencer et al., 2017; Henry et al., 2024; Balasubramanian et al., 2024). However, when it comes to age and sex differences in the deleterious effects of HFD on adult NG and cognitive performance, the rodent studies are not uniform. While some studies demonstrate that HFD reduced the NG and hippocampus-dependent spatial memory in male (Lindqvist et al., 2006; Yoo et al., 2011) but not in female animals (Muscat et al., 2023; Evans et al., 2024), or only in adolescent but not adult mice (Boitard et al., 2012), others showed that females are more vulnerable to the deleterious effects of HFD on cognition and NG (Robison et al., 2020). Interestingly, a maternal HFD suppresses the adult NG in the second and third generations of offsprings via epigenetic mechanisms (Natale et al., 2022). In addition, while a meta-analysis of rodent studies summarizes the severe negative effect of various types of HFD on hippocampus-dependent spatial memory and learning (Abbott et al., 2019), others show that HFD with short duration reduces the amygdala-dependent fear memory while hippocampus-dependent spatial memory remains intact in young female rats (Muscat et al., 2023). Therefore, despite the large volume of animal studies on the topic of diet and brain function, to our knowledge, there is no description of a possible linear dependence of the rodents’ cognitive performance on their body weight when on HFD. In addition, potential sex differences in the impact of HFD on the execution of various cognitive tasks remain elusive.

Based on the above-described studies about the consequences of HFD on cognition, we designed a series of experiments to investigate if a qualitative relationship between weight gain, short- and long-term memory and higher executive function exists in young male and female mice exposed to HFD for three months.

Methods

Animals.

Male and female C57BL/6J mice (strain #000664, Jackson Labs, Bar Harbor, ME) were housed in the biological resource facility at Rosalind Franklin University according to the National Institutes of Health Guide for the Care and Use of Laboratory Animals and with approval of the Institutional Animal Care and Use Committee at the university. For the duration of the study, all mice were housed with a 12:12-h light-dark cycle in cages with standard enrichment and ad libitum access to food and water. Mice were fed a high-fat diet (no. D12492; 60% of caloric intake from fat) or a control diet (no. D12450B; 10% of caloric intake from fat, Research Diets, New Brunswick, NY) from 1 month until 4 months of age. All of the behavior experiments were performed in the period of one week after the mice completed the dietary regimen.

The novel object recognition test (NOR) relies on the rodents’ inclination to spend more time exploring a novel object in their environment than a familiar one. The ratio between the familiar object and the novel object is used to calculate a discrimination index, DI = (TN − TF)/(TN + TF), where T = time spent with the object, F = familiar object, and N = novel object (Antunes and Biala, 2012). The test provides a measure of the animal’s memory for the previously investigated object (recognition memory), which depends on the hippocampus and prefrontal cortex to encode memories about the experience of the objects and, respectively, about the familiarity/novelty of the object (Antunes and Biala, 2012). The habituation of the mice to the test arena was followed by a familiarization part in which the mice were left to explore two similar objects for 5 minutes. Four hours later, the mice were returned to the arena, where one of the objects was replaced by a new object. The used objects were impermeable plastic labware (e.g., test tube holders) that were easy to clean and sanitize and smaller than the mice. The behavior of the mice was analyzed in a blind manner from coded video records using Any-maze automatic tracking.

The puzzle test evaluates the general cognitive (executive) function by assessing the ability of mice to solve a problem (Ben Abdallah et al., 2011; Cardenas, Papadogiannis and Dimitrov, 2021). The test relies on the natural rodent avoidance of open, bright spaces. The test apparatus consists of a well-lit, wide-open compartment connected by a narrow tunnel to a smaller, dark compartment. The mice were placed in the open compartment and allowed to explore the apparatus for five minutes. After crossing the tunnel a few times, the mice consistently entered and remained in the dark compartment. The animals were briefly removed from the box, and a ball made of paper, which the mice can easily pull or push out of the tunnel, was used to block the entrance of the tunnel. The latency to remove the obstacle and enter the dark compartment was used to assess the problem-solving ability of the animals.

Y-Maze Spontaneous Alternations.

This is a behavioral test based on the rodents’ propensity to explore new environments, and it is used to evaluate the spatial working memory in laboratory animals. The test is used as a hippocampus-dependent memory task (Conrad et al., 1996). Mice typically prefer to investigate a new arm of the maze rather than returning to one that was previously visited. We used a Y-shaped maze with three opaque plastic arms at a 120° angle from each other. After introduction to the center of the maze, the animal is allowed to freely explore the maze for 5 minutes. Over the course of multiple arm entries, the animal should show a tendency to enter a less recently visited arm. An entry occurs when all four limbs are within the arm. The number of arm entries and the number of triads are video recorded in order to calculate the percentage of correct spontaneous alternations made by the mice.

Immunohistochemistry.

The lab has extensive experience with evaluation and analysis of NG; the following is a description of our routinely used protocol (Dimitrov et al., 2014; Cardenas et al., 2020). The mice brains were fixed with 4% paraformaldehyde and sectioned into 40 μm thick coronal sections. After pretreatment with blocking solution (0.01M PBS, 0.05% Triton X-100, 3% normal donkey serum) for 2 hours at room temperature, alternate sections were incubated with primary antibodies against Ki67 and DCX in the same blocking solution at 4°C for 48 hours on a rotating platform. The dilutions of primary antibody were 1:1000 rabbit anti-Köln 67 (Ki67, #9129, Cell Signaling Technology, Danvers, MA) and 1:1000 rabbit anti-Doublecortin (DCX, #4604, Cell Signaling Technology, Danvers, MA). Following incubation with the primary antibody, the sections were permeated with solution containing a biotinylated secondary antibody (Jackson Immuno Research Inc., West Grove, PA) in 1:2000 dilution for 2 hours, followed by incubation in avidin-biotin complex (ABC Elite kit, Vector Labs, Burlingame, CA) for 1 hour at room temperature. The fluorescent signal was developed by incubation in 20 nmol of tyramide-conjugated Alexa Fluor 488 fluorescent dye for 12 minutes.

Microscopy.

Images were acquired by a Leica DM 5500 epifluorescent microscope. The Ki67- and DCX-positive cells were counted on sections collected as one in four series, or 8 to 12 sections per animal, that covered the dorsal hippocampus from −1.6 mm to −2.5 mm to bregma. The microscopic images included the entire DG and the adjacent CA1 field. ImageJ (NIH) processing software was used to calculate the Ki67 and DCX, the two markers for NG. The granule cell layer of the DG, the stratum lacunosum, and the molecular layer of the hippocampus were outlined; the resulting area was multiplied by the section thickness and expressed in cubic millimeters. A multi-point tool was used to label immunopositive cells on both blades of the DG. The counts of Ki67 and DCX cells were expressed as cell density by dividing the number of cells by the tissue volume and averaged per animal. All cell counts were performed in a blind manner from coded microscopic slides.

Analysis and statistics.

In all experiments, the recorded data were summarized as means ± SEM. GraphPad Prism 10.5 software was used for all tests; the differences between means were accepted as statistically significant at the 95% level (P < 0.05). For the body weight, the differences between means were compared by an unpaired Student’s t-test. Two-way ANOVA followed by Tukey’s post hoc analysis was used to compare the effects of diet and sex on the outcomes of the cognitive tests. The possible dependence of the cognitive test results on animals’ weight was explored using a Simple Linear Regression analysis, where the body weight (independent variable) was placed on the X axis and the cognitive test results (dependent variables) were placed on the Y axis.

Results

The mice were assigned in random to SD and HFD groups and housed 3 to 4 individuals per cage. The color-coded chow pallets for the two diets and tap water were provided without any restrictions or interruptions for three months. The weight of the animals was verified before the behavior tests. The HFD groups were heavier when compared to the SD groups of both sexes. The body weight of the males was on average 34 g ± 6 for SD group and 48.4 g ± 8.4 for the HFD group, T-test, t27 = 5.4, P < 0.001; the average body weight of female mice on SD was 26.6 g ± 3.5 but reached on average of 43.8 g ± 7.3 for females on HFD, T-test, t29 = 8.6, P < 0.001.

The NOR test uses the innate preference of rodents to explore any new object in their environment. We choose a 4-hour delay interval between the familiarization phase and the testing phase because there are no strain differences in the mice’s performance at this time interval (Sik et al., 2003). The HFD groups spent more time with the familiar object than with the novel object, which led to a negative discrimination index for these groups. A two-way ANOVA test was significant for diet, P < 0.0001, but not for sex and interaction as variables (Figure 1A). The data of the NOR test from all four groups was pooled together, and it was plotted against the weight of the mice. A linear regression analysis of the data where the body weight was an independent variable and the discrimination index was a dependent (response) variable revealed that the discrimination index for novel object depends on the weight of the mice, R2 = 0.33, P < 0.001, (Figure 1B).

Figure 1: The HFD and the body weight impaired object recognition memory in both sexes.

Figure 1:

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A) The male and female mice on HFD spent significantly less time with the novel object when compared to the SD groups, an indication for a loss of long-term recognition memory; Two-way ANOVA test significant for diet, F28 = 58.4, P < 0.0001 but not for sex and interaction. Tukey’s multiple comparisons test was significant for SD male and HFD male groups, q = 9.6, ****P < 0.0001, n = 10/9 and SD females and HFD females, q = 6, **P < 0.01, n = 8/5. B) A regression analysis demonstrated that the discrimination index (preference) for the novel object depends on the body weight of the animal, R2 = 0.33, F30 = 14.5, P < 0.0007.

The results of the Puzzle Box test showed a similar reduction in cognitive performance as a consequence of HFD. The puzzle box test relies on the mice’s aversion to brightly lit spaces, which the mice can escape by removing an obstacle that is blocking their access to the secluded area of the apparatus. This test is used to assess the higher executive function (problem solving ability) of the animals. Again, male and female mice on HFD failed to remove the obstacle before the predetermined cut-off time, as the mice on SD did. A two-way ANOVA test was significant for diet, P < 0.0001, but not for sex and interaction (Figure 2A). The impairment of the cognitive function was dependent on the weight of the mice, R2 = 0.38, P < 0.001, (Figure 2B).

Figure 2: The HFD and the body weight negatively affected the problem-solving ability in both sexes.

Figure 2:

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A) A majority of the male and female mice on HFD failed to remove the obstacle and enter the dark compartment before the cut-off time; Two-way ANOVA significant for diet, F27 = 61.9, P < 0.0001 but not for sex and interaction. Tukey’s multiple comparisons test was significant for SD male and HFD male groups, q = 7.5, ****P < 0.0001, n = 10/8 and SD females and HFD females, q = 8.2, ****P < 0.0001, n = 5/8. B) A regression analysis showed that the latency to enter the dark compartment depends on the body weight of the animal, R2 = 0.38, F30 = 18.4, P < 0.0002.

The Y-maze spontaneous alternations test relies on the intuitive behavior of rodents to navigate through closed spaces and avoid entering the most recently visited arm of the maze. The advantage of this test for working memory is that it does not require special training and does not depend on food baits or aversive stimuli. The mice of both sexes walked similar distances and visited similar number of maze arms regardless of their diet, (Figure 3A and B). However, the male mice on HFD made fewer correct alternations when compared to the males on SD or to the female groups on SD and HFD, which created significant differences for diet but also significance for interaction between diet and sex of the mice; Two-way ANOVA test was significant for diet, P < 0.001, and interaction, P < 0.05 (Figure 3C). Furthermore, as in the previous tests, the number of correct alternations made by the mice was negatively linked to their body weight, linear regression analysis, R2 = 0.34, P < 0.001 (Figure 3D). The results of the Y-maze test showed that HFD and weight gain negatively affect the working memory in male mice, but the females are somewhat resistant to the effect of the HFD on working memory.

Figure 3: The HFD and the body weight negatively affected the working spatial memory only in male mice; the heaviest males made fewer correct alternations.

Figure 3:

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A) Male and female mice on SD or on HFD walked similar distances and B) visited a comparable number of the Y-Maze arms, Two-way ANOVA, P > 0.05 for diet, sex and interaction. C) While the female group on HFD made the same percent of correct alternations as the female group on SD, the male mice on HFD made fewer correct alternations on the maze, an indication of a working memory impairment; Two-way ANOVA significant for diet, F28 = 7.9, P < 0.01, and interaction F28 = 5.2, P < 0.05, but not for sex. A post-hoc analysis showed a significant difference in the percent of correct alternation between SD and HFD males, q = 5.8, **P < 0.01, n = 10/9 but not between SD and HFD female groups, q = 0.4, P > 0.05, n = 8/5. D) A regression analysis showed that the percent of correct alternations depended on the body weight of the mice, R2 = 0.34, F30 = 15.1, P < 0.0005.

The results of the Y-maze experiment compelled us to investigate the effects of diet on hippocampal neurogenesis because of the role of the newborn neurons in the dorsal dentate gyrus of the hippocampus for spatial memory and, more specifically, pattern separation. The brain sections from male and female mice on SD and HFD containing the dorsal hippocampus were immunostained for Ki67 as a marker for neuronal proliferation (duration 1 to 3 days) and DCX as a marker for the early post-mitotic maturation (lasting two to three weeks). Surprisingly, the HFD reduced the number of Ki67-labeled cells only in males but not in females, (Figure 4A to D). The two-way ANOVA test was significant for diet, P < 0.001, and interaction between the sex and diet, P < 0.05 (Figure 4E). The DCX comparison revealed a similar reduction of DCX-positive cells only in male mice on HFD (Figure 5A to D). Two-way ANOVA was significant for diet (P < 0.001) and sex (P < 0.05) and showed a marginal trend for interaction between diet and sex with P = 0.052 (Figure 5E). The results of the experiment support the view that female mice maintain the hippocampal NG when exposed to three months of an HFD regimen.

Figure 4: The HFD decreased the expression of Ki67-labeled cells only in hippocampus of male mice.

Figure 4:

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A) The males on SD showed higher density of Ki67-labeled neurons in the subgranular zone of the dentate gyrus, when compared to B) the HFD group. C) The female mice on SD and D) the female mice on HFD did not show significant difference in the Ki67 expression. E) The average density of Ki67-labeled cells was 7176 ± 1008 cells per mm3 of tissue in SD males but decreased to 4387 ± 771 cells per mm3 of tissue in HFD males. In females, the density of Ki67 cells did not change significantly with diet, the density of SD group was 5741 ± 1115 cells per mm3 of tissue and the density of HFD female group was 4763 ± 894 cells per mm3 of tissue. The two-way ANOVA was significant for diet, F18 = 20.1, P < 0.001, and interaction F18 = 4.6, P < 0.05, but not for sex. A post-hoc analysis showed a significant difference in the cell density between the male groups, q = 6.4, **P < 0.01 but not between the female groups on different diets, q = 2.4, P > 0.05, n = 7/5. Abbreviations: GrDG – granular layer of the dentate gyrus, Mol – molecular layer of the dentate gyrus, PoDG – polymorph layer of the dentate gyrus.

Figure 5: The HFD decreased the expression of DCX-labeled cells only in the hippocampus of male mice.

Figure 5:

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A) The males on SD showed higher density of DCX-labeled neurons in the subgranular zone of the dentate gyrus, when compared to B) males on HFD. The diet did not affect the DCX expression when C) females on SD were compared to D) females on HFD. E) The HFD decreased the density of DCX-labeled cells in the subgranular zone of the dentate gyrus only in male mice: SD males = 26307 ± 4796 DCX cells per mm3 of tissue, HFD males = 17026 ± 1325 DCX cells per mm3 of tissue, SD females = 26491 ± 4171 DCX cells per mm3 of tissue, and HFD females = 24679 ± 5214 DCX cells per mm3 of tissue. The two-way ANOVA test was significant for diet, F18 = 9, P < 0.01, and sex, F18 = 4.7, P < 0.05, but not for interaction, F18 = 4.3, P = 0.052. A post-hoc analysis showed a significant difference in the DCX cell density between the male groups, q = 4.9, *P < 0.05, n = 5/5 but not between the SD and HFD female groups, q = 1.05, P > 0.05, n = 7/5. Abbreviations: GrDG – granular layer of the dentate gyrus, Mol – molecular layer of the dentate gyrus, PoDG – polymorph layer of the dentate gyrus.

Discussion

In sum, while these results reaffirmed the already established negative effect of HFD on cognition, the analysis of these experiments also revealed something new and unexpected - that the severity of cognitive impairment strongly depends on the mice weight. Nonetheless, while the long-term recognition memory and problem-solving ability were negatively affected by weight in both sexes, sex difference in the relationship between the diet and cognitive performance emerged in the Y-maze working memory test, where the heaver females of the HFD group performed equally well when compared to the SD group. The female mice on HFD also showed intact hippocampal neurogenesis, which was considerably reduced in their male counterparts on HFD.

Ethological studies are irreplaceable in neuroscience research. Animal behavior tests are widely used not only in investigations of normal brain functions but are also applied in the research of the vast array of brain disorders. Even research into the mechanisms underlying disorders that affect higher brain functions in humans, such as schizophrenia, dementia and major depression, depends on the behavior tests done in rodents. The reproducibility of the voluminous animal testing is of paramount importance for furthering the preclinical studies but inconsistencies in the readout of rodent behavior tests hinder the translation of the findings into the clinics. Slight differences in the experimental protocols are very likely the cause for the reported differences about the impact of HFD on cognition. There are many factors that must be taken under consideration when planning, executing, and analyzing experiments that rely on animal behavior. The detailed list of variables to consider includes strain, sex, estrous cycle, siblings, maternal care, housing, bedding, environmental enrichment, site of the experiment, experimenter, and so on and so forth; for a wonderful review of the topic see (Sare, Lemons and Smith, 2021). The fasting and the diet of the animals are also included as important factors that may alter behavior (Sare, Lemons and Smith, 2021; Pistell et al., 2010). However, the weight of the mice is not usually considered when performing behavior experiments. The main conclusion of our study is that the weight of the mice plays an important role in their cognitive performance and that there is a strong, linear link between the two, body weight and cognition. The heavier the animal was, the lower was its test score, despite the fact that the weight did not affect the mice’s locomotion, for example, the distance traveled and number of arm entrances on Y-Maze (Figure 3A and B). One shortcoming of the current study is the different sucrose content in the two diet regimens, or 35% sucrose/10% fat in SD chow and 7% sucrose/60% fat in HFD chow. Therefore, knowing the deleterious metabolic effects of a high-sucrose diet, it is possible that the differences in cognitive performance could be much higher if the two diets were matched for a low sucrose content or if a high-sucrose/high-fat diet, which is known to produce the most severe negative impact on cognition (Abbott et al., 2019), was given to HFD groups.

The very likely reason for the linear relationship between weight and cognition is the degree of inflammation in the CNS triggered by HFD. While our study does not include assessment of any inflammatory mediators, the link between HFD, memory and brain inflammation is supported by the reported correlation between the expression of inflammatory mediator interleukin-1β in the hippocampus of male mice on HFD and the percent of correct spontaneous alternations that the animals made on the Y-maze (Almeida-Suhett et al., 2017). The HFD triggers a low-grade inflammation in the brain that causes vascular damage and neuronal apoptosis that inevitably lead to structural brain changes, and it is the main mechanism for obesity-associated cognitive impairment (Gomez-Apo et al., 2021). The decreased density of neuronal progenitor cells Ki67 and DCX in the hippocampus of obese male mice reported here is likely a direct result of lipid peroxidation and decreased levels of brain-derived neurotrophic factor (BDNF) (Park et al., 2010) and illustrates some of the structural damage inflicted by the HFD on the brain. The NG plays an important role in pattern separation and facilitation of remapping of the spatial representation in the dentate gyrus of the hippocampus, which allows the animals to investigate new locations (Tuncdemir et al., 2023). Hence, very likely, the reduction of newborn neurons in the HFD male group resulted in fewer correct alternations by negatively affecting the process of spatial representation in the hippocampus. However, the densities of newborn neurons in the hippocampus of the overweight females were unaffected, which explains the intact short-term spatial memory in the HFD female group. Our results are congruent with our previous findings and the published literature, which shows that various stress paradigms inhibit the NG only in male but not in female animals (Yagi and Galea, 2019; Cardenas et al., 2020). Therefore, the same mechanisms that protect the females from stress-associated reduction of NG are maybe responsible for buffering the effect of HFD. However, the duration of the stressor plays a role in its impacts on NG; therefore, very likely, a longer exposure to HFD than in our study, will reduce the number of newborn neurons in the hippocampus of the female mice. An indicator for this possibility is the density of young proliferating Ki67 cells, which, while not statistically significant at the current level of power due to the small sample size, was somewhat lower in the HFD female group when compared to the SD groups (Figure 4). In addition, the test results of the other two cognitive tests, namely NOR and the Puzzle test, were similarly impaired in overweight female and male mice. The execution of the puzzle test depends not only on normal hippocampal function but also on an intact medial prefrontal cortex (mPFC) (Ben Abdallah et al., 2011), while NOR engages the dentate gyrus, mPFC and dorsomedial striatum (DMS) (Wulaer et al., 2020; Swiercz, Tsuda and Cameron, 2025). Therefore, after three months on HFD, the increased body weight had a similar negative impact on the functions of other brain regions in both sexes except the hippocampus.

In conclusion, the study provides a new insight into the deleterious effects of obesity on cognition. The results show a strong quantitative relationship between the weight of the mice and the significant deterioration of their cognitive ability after exposure to HFD. However, the female mice exposed to HFD for a relatively short period preserved their adult NG and hippocampus-dependent working memory. The takeaway from our study is that the weight of the animals must be considered as an important factor when analyzing animal behavior. Future investigations should address the possible buffering mechanisms that allow the obese female mice to reduce the negative impact of HFD on the NG and hippocampal function.

Highlights.

  • Exposure of male and female mice to a high-fat diet for three months negatively impacts the cognitive performance of the animals.

  • The severity of the cognitive decline is proportional to the increased body weight.

  • While the high-fat diet equally affects long-term memory and problem-solving ability in both sexes, the working spatial memory is unaltered in females.

  • The high-fat diet decreases the hippocampal neurogenesis only in male but not in female mice.

Acknowledgments

The work is supported by NIH grant (HL142906) to Carl White.

Footnotes

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Contributor Information

Yasamin Baghdadchi, 3333 Green Bay Road, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064.

Carl White, 3333 Green Bay Road, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064.

Eugene Dimitrov, 3333 Green Bay Road, Rosalind Franklin University of Medicine and Science, North Chicago, IL 60064.

References:

  1. Abbott KN, Arnott CK, Westbrook RF and Tran DMD (2019) ‘The effect of high fat, high sugar, and combined high fat-high sugar diets on spatial learning and memory in rodents: A meta-analysis’, Neurosci Biobehav Rev, 107, pp. 399–421. [DOI] [PubMed] [Google Scholar]
  2. Almeida-Suhett CP, Graham A, Chen Y and Deuster P (2017) ‘Behavioral changes in male mice fed a high-fat diet are associated with IL-1beta expression in specific brain regions’, Physiol Behav, 169, pp. 130–140. [DOI] [PubMed] [Google Scholar]
  3. Anand SS, Friedrich MG, Lee DS, Awadalla P, Despres JP, Desai D, de Souza RJ, Dummer T, Parraga G, Larose E, Lear SA, Teo KK, Poirier P, Schulze KM, Szczesniak D, Tardif JC, Vena J, Zatonska K, Yusuf S, Smith EE, Canadian Alliance of Healthy, H., Minds, the Prospective, U. and Rural Epidemiological Study, I. (2022) ‘Evaluation of Adiposity and Cognitive Function in Adults’, JAMA Netw Open, 5(2), pp. e2146324. [DOI] [PMC free article] [PubMed] [Google Scholar]
  4. Antunes M and Biala G (2012) ‘The novel object recognition memory: neurobiology, test procedure, and its modifications’, Cogn Process, 13(2), pp. 93–110. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Atak S, Boye A, Pecina S and Liu ZX (2023) ‘High-fat-sugar diet is associated with impaired hippocampus-dependent memory in humans’, Physiol Behav, 268, pp. 114225. [DOI] [PubMed] [Google Scholar]
  6. Balasubramanian P, Kiss T, Gulej R, Nyul Toth A, Tarantini S, Yabluchanskiy A, Ungvari Z and Csiszar A (2024) ‘Accelerated Aging Induced by an Unhealthy High-Fat Diet: Initial Evidence for the Role of Nrf2 Deficiency and Impaired Stress Resilience in Cellular Senescence’, Nutrients, 16(7). [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Ben Abdallah NM, Fuss J, Trusel M, Galsworthy MJ, Bobsin K, Colacicco G, Deacon RM, Riva MA, Kellendonk C, Sprengel R, Lipp HP and Gass P (2011) ‘The puzzle box as a simple and efficient behavioral test for exploring impairments of general cognition and executive functions in mouse models of schizophrenia’, Exp Neurol, 227(1), pp. 42–52. [DOI] [PubMed] [Google Scholar]
  8. Beyer F, Kharabian Masouleh S, Kratzsch J, Schroeter ML, Rohr S, Riedel-Heller SG, Villringer A and Witte AV (2019) ‘A Metabolic Obesity Profile Is Associated With Decreased Gray Matter Volume in Cognitively Healthy Older Adults’, Front Aging Neurosci, 11, pp. 202. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Boitard C, Etchamendy N, Sauvant J, Aubert A, Tronel S, Marighetto A, Laye S and Ferreira G (2012) ‘Juvenile, but not adult exposure to high-fat diet impairs relational memory and hippocampal neurogenesis in mice’, Hippocampus, 22(11), pp. 2095–100. [DOI] [PubMed] [Google Scholar]
  10. Cardenas A, Caniglia J, Keljalic D and Dimitrov E (2020) ‘Sex differences in the development of anxiodepressive-like behavior of mice subjected to sciatic nerve cuffing’, Pain, 161(8), pp. 1861–1871. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Cardenas A, Papadogiannis A and Dimitrov E (2021) ‘The role of medial prefrontal cortex projections to locus ceruleus in mediating the sex differences in behavior in mice with inflammatory pain’, FASEB J, 35(7), pp. e21747. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Clifton P (2019) ‘Metabolic Syndrome-Role of Dietary Fat Type and Quantity’, Nutrients, 11(7). [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Conrad CD, Galea LA, Kuroda Y and McEwen BS (1996) ‘Chronic stress impairs rat spatial memory on the Y maze, and this effect is blocked by tianeptine pretreatment’, Behav Neurosci, 110(6), pp. 1321–34. [DOI] [PubMed] [Google Scholar]
  14. Cordain L, Eaton SB, Sebastian A, Mann N, Lindeberg S, Watkins BA, O’Keefe JH and Brand-Miller J (2005) ‘Origins and evolution of the Western diet: health implications for the 21st century’, Am J Clin Nutr, 81(2), pp. 341–54. [DOI] [PubMed] [Google Scholar]
  15. Dimitrov EL, Tsuda MC, Cameron HA and Usdin TB (2014) ‘Anxiety- and depression-like behavior and impaired neurogenesis evoked by peripheral neuropathy persist following resolution of prolonged tactile hypersensitivity’, J Neurosci, 34(37), pp. 12304–12. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Evans AK, Saw NL, Woods CE, Vidano LM, Blumenfeld SE, Lam RK, Chu EK, Reading C and Shamloo M (2024) ‘Impact of high-fat diet on cognitive behavior and central and systemic inflammation with aging and sex differences in mice’, Brain Behav Immun, 118, pp. 334–354. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Favieri F, Forte G and Casagrande M (2019) ‘The Executive Functions in Overweight and Obesity: A Systematic Review of Neuropsychological Cross-Sectional and Longitudinal Studies’, Front Psychol, 10, pp. 2126. [DOI] [PMC free article] [PubMed] [Google Scholar]
  18. Freeman LR, Haley-Zitlin V, Rosenberger DS and Granholm AC (2014) ‘Damaging effects of a high-fat diet to the brain and cognition: a review of proposed mechanisms’, Nutr Neurosci, 17(6), pp. 241–51. [DOI] [PMC free article] [PubMed] [Google Scholar]
  19. Fung TT, Rimm EB, Spiegelman D, Rifai N, Tofler GH, Willett WC and Hu FB (2001) ‘Association between dietary patterns and plasma biomarkers of obesity and cardiovascular disease risk’, Am J Clin Nutr, 73(1), pp. 61–7. [DOI] [PubMed] [Google Scholar]
  20. Gomez-Apo E, Mondragon-Maya A, Ferrari-Diaz M and Silva-Pereyra J (2021) ‘Structural Brain Changes Associated with Overweight and Obesity’, J Obes, 2021, pp. 6613385. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Henry RJ, Barrett JP, Vaida M, Khan NZ, Makarevich O, Ritzel RM, Faden AI and Stoica BA (2024) ‘Interaction of high-fat diet and brain trauma alters adipose tissue macrophages and brain microglia associated with exacerbated cognitive dysfunction’, J Neuroinflammation, 21(1), pp. 113. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Lindqvist A, Mohapel P, Bouter B, Frielingsdorf H, Pizzo D, Brundin P and Erlanson-Albertsson C (2006) ‘High-fat diet impairs hippocampal neurogenesis in male rats’, Eur J Neurol, 13(12), pp. 1385–8. [DOI] [PubMed] [Google Scholar]
  23. Muscat SM, Butler MJ, Mackey-Alfonso SE and Barrientos RM (2023) ‘Young adult and aged female rats are vulnerable to amygdala-dependent, but not hippocampus-dependent, memory impairment following short-term high-fat diet’, Brain Res Bull, 195, pp. 145–156. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Natale F, Spinelli M, Barbati SA, Leone L, Fusco S and Grassi C (2022) ‘High Fat Diet Multigenerationally Affects Hippocampal Neural Stem Cell Proliferation via Epigenetic Mechanisms’, Cells, 11(17). [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Park HR, Park M, Choi J, Park KY, Chung HY and Lee J (2010) ‘A high-fat diet impairs neurogenesis: involvement of lipid peroxidation and brain-derived neurotrophic factor’, Neurosci Lett, 482(3), pp. 235–9. [DOI] [PubMed] [Google Scholar]
  26. Pistell PJ, Morrison CD, Gupta S, Knight AG, Keller JN, Ingram DK and Bruce-Keller AJ (2010) ‘Cognitive impairment following high fat diet consumption is associated with brain inflammation’, J Neuroimmunol, 219(1–2), pp. 25–32. [DOI] [PMC free article] [PubMed] [Google Scholar]
  27. Robison LS, Albert NM, Camargo LA, Anderson BM, Salinero AE, Riccio DA, Abi-Ghanem C, Gannon OJ and Zuloaga KL (2020) ‘High-Fat Diet-Induced Obesity Causes Sex-Specific Deficits in Adult Hippocampal Neurogenesis in Mice’, eNeuro, 7(1). [DOI] [PMC free article] [PubMed] [Google Scholar]
  28. Sare RM, Lemons A and Smith CB (2021) ‘Behavior Testing in Rodents: Highlighting Potential Confounds Affecting Variability and Reproducibility’, Brain Sci, 11(4). [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Sharma S (2021) ‘High fat diet and its effects on cognitive health: alterations of neuronal and vascular components of brain’, Physiol Behav, 240, pp. 113528. [DOI] [PubMed] [Google Scholar]
  30. Sik A, van Nieuwehuyzen P, Prickaerts J and Blokland A (2003) ‘Performance of different mouse strains in an object recognition task’, Behav Brain Res, 147(1–2), pp. 49–54. [DOI] [PubMed] [Google Scholar]
  31. Spencer SJ, D’Angelo H, Soch A, Watkins LR, Maier SF and Barrientos RM (2017) ‘High-fat diet and aging interact to produce neuroinflammation and impair hippocampal- and amygdalar-dependent memory’, Neurobiol Aging, 58, pp. 88–101. [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. Swiercz AP, Tsuda MC and Cameron HA (2025) ‘The curious interpretation of novel object recognition tests’, Trends Neurosci, 48(4), pp. 250–256. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. Tuncdemir SN, Grosmark AD, Chung H, Luna VM, Lacefield CO, Losonczy A and Hen R (2023) ‘Adult-born granule cells facilitate remapping of spatial and non-spatial representations in the dentate gyrus’, Neuron, 111(24), pp. 4024–4039 e7. [DOI] [PMC free article] [PubMed] [Google Scholar]
  34. Wulaer B, Kunisawa K, Kubota H, Suento WJ, Saito K, Mouri A and Nabeshima T (2020) ‘Prefrontal cortex, dorsomedial striatum, and dentate gyrus are necessary in the object-based attention test in mice’, Mol Brain, 13(1), pp. 171. [DOI] [PMC free article] [PubMed] [Google Scholar]
  35. Yagi S and Galea LAM (2019) ‘Sex differences in hippocampal cognition and neurogenesis’, Neuropsychopharmacology, 44(1), pp. 200–213. [DOI] [PMC free article] [PubMed] [Google Scholar]
  36. Yeomans MR, Armitage R, Atkinson R, Francis H and Stevenson RJ (2023) ‘Habitual intake of fat and sugar is associated with poorer memory and greater impulsivity in humans’, PLoS One, 18(8), pp. e0290308. [DOI] [PMC free article] [PubMed] [Google Scholar]
  37. Yoo DY, Kim W, Nam SM, Yoo KY, Lee CH, Choi JH, Won MH, Hwang IK and Yoon YS (2011) ‘Reduced cell proliferation and neuroblast differentiation in the dentate gyrus of high fat diet-fed mice are ameliorated by metformin and glimepiride treatment’, Neurochem Res, 36(12), pp. 2401–8. [DOI] [PubMed] [Google Scholar]

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