A review of the effects of mushrooms on mood and neurocognitive health across the lifespan

Mushrooms contain bioactive compounds with documented antioxidant and anti-inflammatory actions. Here, we present a systematic evaluation of epidemiological and clinical studies that investigate the role of mushrooms, either as a separate or integral dietary component, on neurocognition and mood. Following a search of four databases, a total of 34 human studies examining the effect of different mushrooms across varying age cohorts and health statuses were selected for inclusion. Epidemiological studies included in this review (n = 24) revealed a significant benefit of dietary patterns that included mushrooms of any species on cognition and mood in both healthy and compromised populations. However, the results obtained from intervention studies (n = 10) were mixed. Studies mainly investigated Lion's Mane (Hericium erinaceus), showing some enhancement of mood and cognitive function in middle-aged and older adults. Further acute and chronic human intervention studies are needed, using adequate sample sizes, employing appropriately sensitive neurocognitive tests, and investigating a range of dietary mushrooms, to confirm the effects of mushroom supplementation on neurocognition and mood in humans.

Effects of HZE-Particle Exposure Location and Energy on Brain Inflammation and Oxidative Stress in Rats

Astronauts on exploratory missions will be exposed to particle radiation of high energy and charge (HZE particles), which have been shown to produce neurochemical and performance deficits in animal models. Exposure to HZE particles can produce both targeted effects, resulting from direct ionization of atoms along the particle track, and non-targeted effects (NTEs) in cells that are distant from the track, extending the range of potential damage beyond the site of irradiation. While recent work suggests that NTEs are primarily responsible for changes in cognitive function after HZE exposures, the relative contributions of targeted and non-targeted effects to neurochemical changes after HZE exposures are unclear. The present experiment was designed to further explore the role of targeted and non-targeted effects on HZE-induced neurochemical changes (inflammation and oxidative stress) by evaluating the effects of exposure location and particle energy/linear energy transfer (LET). Forty-six male Sprague-Dawley rats received head-only or body-only exposures to 56Fe particles [600 MeV/n (75 cGy) or 1,000 MeV/n (100 cGy)] or 48Ti particles [500 MeV/n (50 cGy) or 1,100 MeV/n (75 cGy)] or no irradiation (0 cGy). Twenty-four h after irradiation, rats were euthanized, and the brain was dissected for analysis of HZE-particle-induced neurochemical changes in the hippocampus and frontal cortex. Results showed that exposure to 56Fe and 48Ti ions produced changes in measurements of brain inflammation [glial fibrillary astrocyte protein (GFAP)], oxidative stress [NADPH-oxidoreductase-2 (NOX2)] and antioxidant enzymes [superoxide dismutase (SOD), glutathione S-transferase (GST), nuclear factor erythroid 2-related factor 2 (Nrf2)]. However, radiation effects varied depending upon the specific measurement, brain region, and exposure location. Although overall exposures of the head produced more detrimental changes in neuroinflammation and oxidative stress than exposures of the body, body-only exposures also produced changes relative to no irradiation, and the effect of particle energy/LET on neurochemical changes was minimal. Results indicate that both targeted and non-targeted effects are important contributors to neurochemical changes after head-only exposure. However, because there were no consistent neurochemical changes as a function of changes in track structure after head-only exposures, the role of direct effects on neuronal function is uncertain. Therefore, these findings, although in an animal model, suggest that NTEs should be considered in the estimation of risk to the central nervous system (CNS) and development of countermeasures.

Perspective: Council for Responsible Nutrition Science in Session. Optimizing Health with Nutrition-Opportunities, Gaps, and the Future

Achieving optimal health is an aspirational goal for the population, yet the definition of health remains unclear. The role of nutrition in health has evolved beyond correcting malnutrition and specific deficiencies and has begun to focus more on achieving and maintaining 'optimal' health through nutrition. As such, the Council for Responsible Nutrition held its October 2022 Science in Session conference to advance this concept. Here, we summarize and discuss the findings of their Optimizing Health through Nutrition - Opportunities and Challenges workshop, including several gaps that need to be addressed to advance progress in the field. Defining and evaluating various indices of optimal health will require overcoming these key gaps. For example, there is a strong need to develop better biomarkers of nutrient status, including more accurate markers of food intake, as well as biomarkers of optimal health that account for maintaining resilience-the ability to recover from or respond to stressors without loss to physical and cognitive performance. In addition, there is a need to identify factors that drive individualized responses to nutrition, including genotype, metabotypes, and the gut microbiome, and to realize the opportunity of precision nutrition for optimal health. This review outlines hallmarks of resilience, provides current examples of nutritional factors to optimize cognitive and performance resilience, and gives an overview of various genetic, metabolic, and microbiome determinants of individualized responses.

Perspective: Challenges and Future Directions in Clinical Research with Nuts and Berries

Consumption of nuts and berries are considered part of a healthy eating pattern. Nuts and berries contain a complex nutrient profile consisting of essential vitamins and minerals, fiber, polyunsaturated fatty acids, and phenolics in quantities that improve physiological outcomes. The spectrum of health outcomes that may be impacted by the consumptions of nuts and berries includes cardiovascular, gut microbiome, and cognitive, among others. Recently, new insights regarding the bioactive compounds found in both nuts and berries have reinforced their role for use in precision nutrition efforts. However, challenges exist that can affect the generalizability of outcomes from clinical studies, including inconsistency in study designs, homogeneity of test populations, variability in test products and control foods, and assessing realistic portion sizes. Future research centered on precision nutrition and multi-omics technologies will yield new insights. These and other topics such as funding streams and perceived risk-of-bias were explored at an international nutrition conference focused on the role of nuts and berries in clinical nutrition. Successes, challenges, and future directions with these foods are presented here.

Effects of preexposure to a subthreshold dose of helium particles on the changes in performance produced by exposure to helium particles

On exploratory class missions, such as a mission to Mars, astronauts will be exposed to doses of particles of high energy and charge and protons up to 30 - 40 cGy. These exposures will most likely occur at random intervals across the estimated 3-yr duration of the mission. As such, the possibility of an interaction between particles must be taken into account: a prior subthreshold exposure to one particle may prevent or minimize the effect of a subsequent exposure (adaptation), or there may be an additive effect such that the prior exposure may sensitize the individual to a subsequent exposure of the same or different radiations. Two identical replications were run in which rats were exposed to a below threshold dose of ⁴He particles and 2, 24 or 72 h later given either a second below threshold or an above threshold dose of ⁴He particles and tested for performance on an operant task. The results indicate that preexposure to a subthreshold dose of ⁴He particles can either sensitize or attenuate the effects of the subsequent dose, depending upon the interval between exposures and the doses. These results suggest that exposure to multiple doses of heavy particles may have implications for astronaut health on exploratory class missions.

Blueberry treatment administered before and/or after lipopolysaccharide stimulation attenuates inflammation and oxidative stress in rat microglial cells

ABSTRACTMicroglia are key regulators of inflammation and oxidative stress (OS) in the CNS. Microglia activation can lead to chronic inflammation, OS, and neurodegeneration. Blueberries (BB) reduce inflammation and OS when administered to microglia before stressors such as lipopolysaccharide (LPS), but the therapeutic value of BBs administered after activation by stressors has not been examined. Therefore, this study investigated the differential effects of pre-, post-, and pre-/post-BB on inflammation and OS in LPS-activated microglia. Rat microglia were pretreated with BB (0.5 mg/mL) or control media (C) for 24 hours, incubated overnight with LPS (0 or 200 ng/mL), and post-treated with BB or C for 24 hours. Biomarkers of inflammation (e.g. nitrite [NO₂^-], tumor necrosis factor-ɑ [TNFɑ], inducible nitric oxide synthase [iNOS], cyclooxygenase-2 [COX-2], phosphorylated IκB-α [pIκB-ɑ]) and OS (e.g. NADPH oxidase [NOX2]) were assessed. LPS increased NO₂^-, TNFɑ, COX-2, iNOS, pIκB-ɑ, and NOX2 compared to non-stressed conditions (P < 0.05), however BB before and/or after LPS significantly reduced these markers compared to no BB (P < 0.05). Pre-BB was more effective than post-BB at reducing LPS-induced NO₂^-, TNFɑ, and COX-2 (P < 0.05). Pre-BB was also more effective than pre-/post-BB at attenuating LPS-induced NO₂^- and TNFɑ (P < 0.05). All BB treatments were equally effective in reducing LPS-induced iNOS, pIκB-ɑ, and NOX2. Results suggest that BBs can target the downstream events of LPS-induced microglial activation and prevent stressor-induced neuroinflammation and OS. Furthermore, BBs may not need to be present prior to microglial activation for beneficial effects, suggesting that dietary interventions may be effective even after initiation of disease processes.Graphical Abstract. Cascade of inflammatory and OS-inducing events associated with self-propelling microglial activation by LPS and the effects of blueberry (0.5 mg/mL) administered before and/or after LPS on these processes (blue arrows). BB, blueberry; COX2, cyclooxygenase-2; IκB-ɑ, inhibitor kappa-B-ɑ; iNOS, inducible nitric oxide synthase; LPS, lipopolysaccharide; NF-κB, nuclear factor kappa-B; NO, nitric oxide; NOX2, NADPH oxidase; OS, oxidative stress; ROS, reactive oxygen species; TNFɑ, tumor necrosis factor-ɑ.

Protective Effects of a Polyphenol-Rich Blueberry Extract on Adult Human Neural Progenitor Cells

The aging process impacts neural stem cells and causes a significant decline in neurogenesis that contributes to neuronal dysfunction leading to cognitive decline. Blueberries are rich in polyphenols and have been shown to improve cognition and memory in older humans. While our previous studies have shown that blueberry supplementations can increase neurogenesis in aged rodents, it is not clear whether this finding can be extrapolated to humans. We thus investigated the effects of blueberry treatments on adult hippocampal human neural progenitor cells (AHNPs) that are involved in neurogenesis and potentially in memory and other brain functions. Cultured AHNPs were treated with blueberry extract at different concentrations. Their viability, proliferation, and differentiation were evaluated with and without the presence of a cellular oxidative stressor, dopamine, and potential cellular mechanisms were also investigated. Our data showed that blueberry extract can significantly increase the viability and proliferation rates of control hippocampal AHNPs and can also reverse decreases in viability and proliferation induced by the cellular stressor dopamine. These effects may be associated with blueberry’s anti-inflammatory, antioxidant, and calcium-buffering properties. Polyphenol-rich berry extracts thus confer a neuroprotective effect on human hippocampal progenitor cells in vitro.

Long-Term Supplementation With Fruits and Vegetables Prevents Western-Style High-Fat Diet-Induced Cognitive Impairment in Mice

Objectives

Aging, obesity and a high-fat diet is associated with increased risk of cognitive impairment. Epidemiological studies suggest that increased fruits and vegetables (FV) intake is associated with a reduced risk of cognitive dysfunction. However, causal relationship between FV intake and cognition has not been established. The objective of this study was to investigate the causal effect of long-term FV supplementation in context of a low fat or Western-style high-fat diet in mice.

Methods

Using a 2 × 2 factorial prospective design, male C57BL/6J (5-wk) were randomly assigned to one of four groups (20/group): low fat control (LF-C, 10% kcal fat), high fat control (HF-C, 45% kcal fat), and each with 15% of a unique mixture of FV (patent pending) (w/w) (LF-FV and HF-FV). Novel object recognition test (NOR), a cognitive test for measuring exploration, memory, and object recognition, was performed to evaluate mouse cognitive function at 18 months. As rodents have an innate preference for exploring novelty, a mouse that remembers the familiar object will spend more time exploring the novel object, which indicates intact cognitive function. Next, recognition index (RI) was calculated based on the time the mouse spent exploring the new object over total object exploration time. The performance was analyzed with ANOVA, followed by Tukey's multiple comparisons test when appropriate.

Results

Compared to the LF-C group, mice fed the HF diet for 18 months had significantly lower RI in the NOR test (RI = 0.2100 for LF-C and RI = −0.04559 for HF-C, respectively, p < 0.0001), indicating cognitive impairment in the HF-C group. FV supplementation significantly mitigated the HF diet-induced cognitive impairment (RI = 0.2066 for HF-FV vs. RI = −0.04559 for HF-C, p < 0.0001). No significant difference in RI was observed between the LF-C mice (RI = 0.2100) and the LF-FV mice (RI = 0.2323).

Conclusions

This study provides evidence for a causal role of high intake of FV in preventing Western-style high-fat diet-induced cognition impairment in mice. The mechanisms by which FV improves cognitive function is currently under investigation.

Funding Sources

This material is based upon work supported by the U.S. Department of Agriculture – Agricultural Research Service (ARS), under Agreement No. 58-8050-9-004.

Low Vitamin K Intake Negatively Affects C57BL6 Mouse Survival and Cognition

Objectives

Low dietary intake of vitamin K (VK), which is common among older adults, has been associated with age-related dementia and cognitive impairment. Aging and neurodegenerative diseases negatively affect hippocampal neurogenesis, and result in cognitive deficits, such as in learning and memory. The current study investigated the effects of low vitamin K intake on the potential factors affecting the cognitive functions in a C57BL6 mouse model.

Methods

Middle-aged (7–9 mo) C57BL6 mice (Charles River, n = 60) were randomly assigned by sex and diet (n = 15/group): low vitamin K males (LVKM, 80 μg phylloquinone (PK)/kg diet), control diet males (CM, 1 mg PK/kg diet), low vitamin K females (LVKF), and control diet females (CFM) for 6 months. All animals were fed ad lib, and their body weight were recorded 1–2 times/week. At the completion of the 6-mo feeding period, behavioral tests, including the rotarod, novel object task, and Morris water maze, were performed. Tissue samples were collected at the time of sacrifice (3 weeks after the behavioral tests) and PK content in liver samples were measured by HPLC.

Results

LVKM had significantly lower survival rate compared to CM (53.3% vs. 93.3% in control, P &lt; 0.05). LVKM/F also had reduced body weight increases compared to the CM/F over the 6 mo feeding period (P &lt; 0.05). The liver PK content in LVKM/F animals was significantly lower than that of CM/F (male:6.2 ± 1.1 vs 30.2 ± 7.0 pmol/g, P &lt; 0.001; female: 10.9 ± 2.4 vs 47.3 ± 10.3 pmol/g, P &lt; 0.001). On the novel object task, LVKM/F showed reduced recognition memory compared to CM/F, while no significant differences were seen between LVKM/F and CM/F on the rotarod test. Additionally, LVKM had a non-statistical trend for a greater time to locate the platform in the Morris water maze, suggesting impaired spatial memory.

Conclusions

Low vitamin K intake significantly impaired survival and weight gain of C57BL6 mice, especially among males. Additionally, low vitamin K negatively impacted the learning- and memory-related cognitive functions. Future studies are required to establish the mechanisms, underlying these observations.

Funding Sources

Supported by USDA/ARS intramural grant, and the Robert and Margaret Patricelli Family Foundation

The Impact of a Walnut-Rich Breakfast on Cognitive Performance Throughout the Day in Healthy Young Adults

Objectives

A healthy diet is essential for optimal brain health. A number of food bioactives have been linked to cognitive benefits, including phytonutrients and essential fatty acids. Here we investigated the benefits of a walnut-rich breakfast, which contained flavonoids and omega-3s, to see whether consumption of these bioactives might lead to significant cognitive improvements throughout the day.

Methods

A double-blind, crossover intervention study compared the effects of a breakfast containing 50g walnuts, with a nut-free, macronutrient-matched control. Participants were 32 healthy, young adults aged 18 to 30. Cognition, mood, blood, and EEG measures were recorded at baseline and 2, 4, and 6 hours postprandially. Only the cognitive data are reported here. All cognitive data were analyzed using linear mixed modeling (LMM) with baseline performance included as a covariate. Bonferroni corrected pairwise comparisons were used to investigate significant treatment effects.

Results

Compared to the control breakfast, the walnuts elicited significantly faster reaction times throughout the day on tasks measuring inhibition and task switching aspects of executive function. Memory recall results were mixed; slightly worse performance was observed at 2 hours following the walnut breakfast, but this was later reversed with walnuts outperforming control at 6 hours.

Conclusions

The findings provide evidence for reaction time benefits following a walnut-rich breakfast, with effects lasting throughout the day. The results concur with previous literature that suggests executive function effects are commonly observed in young adults following flavonoid supplementation. The memory recall effect at the final time point is consistent with previously observed benefits for both omega-3 fatty acids and flavonoids and may indicate that walnuts offer neuroprotection following long periods of cognitive demand, or that memory benefits depend upon the slower absorption of omega-3s or the delayed appearance of flavonoid metabolites. Walnuts are therefore beneficial to cognitive function in young adults after only a single, acute intake, but further investigation of precise mechanisms is needed.

Funding Sources

The study was funded by the California Walnut Commission, USA and pre-registered at clinicaltrials.gov.

Berry Phenolics Are Associated With Cognitive Enhancement in Blueberry- and Strawberry-Supplemented Older Adults

Objectives

Research suggests that supplementation with berries may improve cognition during aging. In two recently published 90-day trials, healthy older adults (ages 60–75; BMI 18.5–29.9) who consumed 24 g/d freeze-dried blueberry or strawberry showed improved cognitive function, relative to placebo controls. However, the mechanism of action underlying these cognitive benefits and the role of berry phenolics in cognitive enhancement is not fully understood. In this study, we hypothesized that dietary supplementation with blueberry or strawberry would increase the concentrations of circulating phenolics in healthy older adults and that these changes would be associated with the enhanced cognitive measures observed in these trials.

Methods

Anthocyanins and phenolic acids, including both parent compounds and metabolites, were quantiifed in plasma from the two trials after an overnight fast and 2-h postprandially at each time point (day 0, 45, 90) using HPLC. Metabolite concentrations were analyzed by two-way ANOVA followed by post hoc testing with Fisher's LSD to determine differences between the groups. Regression analysis was performed on the change in individual berry phenolic (D90-D0) and the change in measures of cognition (D90-D0).

Results

Of the 30 phenolic acids and anthocyanins detected in our samples, blueberry and strawberry significantly increased plasma concentrations of 18 phenolics (group x visit interaction, p &lt; 0.05) at the fasting and postprandial time points. Most phenolic compounds were metabolized and returned to baseline concentrations following an overnight fast; however, phenolic acids, particularly hippuric acid, were retained in circulation, suggesting potential adaptation. Regression analysis determined a significant association in a number of phenolics and improvements in executive function and memory (P &lt; 0.05).

Conclusions

Blueberry and strawberry polyphenols are absorbed and extensively metabolized, resulting in the production of phenolic acid derivatives and their conjugates. Furthermore, altered plasma concentrations of individual blueberry and strawberry polyphenolics were associated with improvements in cognition.

Funding Sources

Supported by USDA intramural funds, the U.S. Highbush Blueberry Council and the California Strawberry Commission.

Walnut Oil and Blueberry Treatments Have Beneficial Individual but Not Synergistic Effects on Neuroinflammation In Vitro

Objectives

Neuroinflammation has been associated with cognitive decline and neurodegenerative disease. Walnuts and blueberries (BB) each provide neuroprotective anti-inflammatory components. However, it is unknown whether they act synergistically to enhance the effects seen with individual supplementation. This study aimed to examine the individual and potentially synergistic beneficial effects of walnut oil (WO) and BB on lipopolysaccharide (LPS)-induced neuroinflammation in rat microglial cells. The effects of pre-treatment time and concentration were also explored.

Methods

Rat microglial cells were pre-treated for 48 hours, 1, 2 or 4 weeks with control media or freeze-dried BB extract, WO or WO/BB diluted in media at 0.05, 0.1, 0.2, 0.5 and 1.0 mg/mL. At the end of each treatment time point, cells were stressed with LPS (100 ng/mL) overnight. Standard immunochemical techniques were used to measure biomarkers of inflammation: nitrite, inducible nitrous oxide synthase (iNOS), and cyclooxygenase-2 (COX-2). Data were analyzed using three-way ANOVAs with treatment, concentration, and time as experimental factors, and Tukey's post-hoc test to determine differences among groups.

Results

Results showed that BB, WO, and WO/BB reduced LPS-induced nitrite, COX2 and iNOS relative to control (P &lt; 0.05). BB had a stronger effect on reducing nitrite production than WO/BB, and both BB and WO/BB were more effective than WO (P &lt; 0.05). However, there were no significant differences between treatments for COX2 and iNOS expression. All three treatments attenuated LPS-induced nitrite, COX2, and iNOS in a concentration- and time-dependent manner (P &lt; 0.05), with higher doses and longer treatment durations being most beneficial.

Conclusions

Although BB, WO and WO/BB reduced LPS-induced neuroinflammation, WO/BB was not more effective than either individual treatment. This result suggests that BB and WO do not act synergistically to attenuate inflammation in microglia. Additionally, the intermediate effect of WO/BB relative to BB and WO on nitrite suggests that BB is primarily responsible for the beneficial effects of WO/BB. Overall, the reduction in neuroinflammation following all treatments shows that the addition of blueberries and/or walnuts to the diet may attenuate the neurodegenerative effects of inflammation.

Funding Sources

Supported by USDA intramural funding.

Blueberry Treatment Administered Before and/or After Lipopolysaccharide Attenuates Neuroinflammation and Oxidative Stress in Rat Microglial Cells

Objectives

Neuroinflammation and oxidative stress (OS) are implicated as mediators of cognitive decline and neurodegenerative diseases. Microglia, the primary immune cells of the central nervous system (CNS), are key regulators of inflammation and OS in the CNS. Blueberries (BB) are rich in anti-inflammatory and antioxidant polyphenols and reduce inflammation and OS when administered to microglia before pathogenic stimuli such as lipopolysaccharide (LPS). However, the therapeutic value of BBs administered to microglial cells after activation by LPS on inflammation and OS has not been examined. This study investigated the potential differential effects of pre-, post-, and pre-/post-BB on LPS-induced inflammation and OS in rat microglia.

Methods

Rat microglia were pre-treated with freeze-dried BB diluted in media (0.5 mg/mL) or control media (C) for 24 h, incubated overnight with LPS (0 or 100 ng/mL), and post-treated with BB or C for 24 h. Standard immunochemical techniques were used to measure biomarkers of inflammation and OS, including nitrite, tumor necrosis factor alpha (TNFɑ), inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2). Data were analyzed using two-way ANOVAs with treatment group (pre-/post-BB) and LPS exposure as experimental factors. Post-hoc testing was performed using Tukey's test to determine differences among groups.

Results

Preliminary results showed that all BB treatments (pre-, post- and pre-/post-BB) reduced LPS-induced nitrite and TNFɑ relative to no BB (P &lt; 0.01). Pre-BB was more effective at reducing nitrite than post-BB (P &lt; 0.01), although neither was significantly different than pre-/post-BB. In contrast, the attenuating effects of pre-BB and post-BB on TNFɑ were not different from each other, although both treatments were more beneficial than pre-/post-BB (P &lt; 0.001). Compared to no BB, both pre-BB and post-BB, although not pre-/post-BB reduced LPS-induced iNOS expression (P &lt; 0.05), and only pre-BB attenuated COX2 expression (P &lt; 0.01).

Conclusions

Results suggest that BBs can target the downstream effects of microglial activation in addition to preventing stressor-induced neuroinflammation and OS. Therefore, although potentially more effective, BBs may not need to be present prior to microglial activation for beneficial effects.

Funding Sources

Supported by USDA intramural funding.

Modeling space radiation induced cognitive dysfunction using targeted and non-targeted effects

Radiation-induced cognitive dysfunction is increasingly recognized as an important risk for human exploration of distant planets. Mechanistically-motivated mathematical modeling helps to interpret and quantify this phenomenon. Here we considered two general mechanisms of ionizing radiation-induced damage: targeted effects (TE), caused by traversal of cells by ionizing tracks, and non-targeted effects (NTE), caused by responses of other cells to signals released by traversed cells. We compared the performances of 18 dose response model variants based on these concepts, fitted by robust nonlinear regression to a large published data set on novel object recognition testing in rats exposed to multiple space-relevant radiation types (H, C, O, Si, Ti and Fe ions), covering wide ranges of linear energy transfer (LET) (0.22-181 keV/µm) and dose (0.001-2 Gy). The best-fitting model (based on Akaike information criterion) was an NTE + TE variant where NTE saturate at low doses (~ 0.01 Gy) and occur at all tested LETs, whereas TE depend on dose linearly with a slope that increases with LET. The importance of NTE was also found by additional analyses of the data using quantile regression and random forests. These results suggest that NTE-based radiation effects on brain function are potentially important for astronaut health and for space mission risk assessments.

Healthy Aging-Nutrition Matters: Start Early and Screen Often

The amount of time spent in poor health at the end of life is increasing. This narrative review summarizes consistent evidence indicating that healthy dietary patterns and maintenance of a healthy weight in the years leading to old age are associated with broad prevention of all the archetypal diseases and impairments associated with aging including: noncommunicable diseases, sarcopenia, cognitive decline and dementia, osteoporosis, age-related macular degeneration, diabetic retinopathy, hearing loss, obstructive sleep apnea, urinary incontinence, and constipation. In addition, randomized clinical trials show that disease-specific nutrition interventions can attenuate progression-and in some cases effectively treat-many established aging-associated conditions. However, middle-aged and older adults are vulnerable to unhealthy dietary patterns, and typically consume diets with inadequate servings of healthy food groups and essential nutrients, along with an abundance of energy-dense but nutrient-weak foods that contribute to obesity. However, based on menu examples, diets that are nutrient-dense, plant-based, and with a moderately low glycemic load are better equipped to meet the nutritional needs of many older adults than current recommendations in US Dietary Guidelines. These summary findings indicate that healthy nutrition is more important for healthy aging than generally recognized. Improved public health messaging about nutrition and aging, combined with routine screening and medical referrals for age-related conditions that can be treated with a nutrition prescription, should form core components of a national nutrition roadmap to reduce the epidemic of unhealthy aging.

Blueberry phenolics are associated with cognitive enhancement in supplemented healthy older adults

Blueberries (BB) contain an array of bioactive phenolic compounds that may play a protective role against various age-related diseases. Here we explored the metabolic fate of BB phenolics and their relationship to cognitive function after chronic (90 days) supplementation of freeze-dried BB (24 g d^-1, equivalent to 1 cup of fresh BB) or control in a randomized, double-blind, parallel study with 38 healthy older adults (60-75 years). Blood samples were collected at fasting (t = 0 h) and 2 h after a breakfast meal on days 0 (no treatment), 45, and 90, and a battery of cognitive tests was also conducted on these days. Hippuric acid, phloroglucinaldehyde, syringic acid, ferulic acid-glucuronide, cyanidin-3-O-galactoside, cyanidin-3-O-glucoside, malvidin-3-O-galactoside, malvidin-3-O-glucoside, peonidin-3-O-xyloside, peonidin glucuronide, and petunidin-3-O-glucoside concentrations were significantly altered after 90 days of BB consumption compared to control. Stepwise regression was used to assess the relationship between significantly altered concentrations of plasma phenolics and observed improvements in cognition. Among participants in the BB group, changes in switch errors on the task-switching test (TST) from day 0 to 90 were associated with changes in postprandial levels of plasma ferulic acid-glucuronide, syringic acid, and malvidin-3-galactoside (R² = 0.521, p < 0.05). Changes in repetition errors on the California Verbal Learning Test (CVLT-II) from day 0 to 90 were associated with changes in postprandial levels of ferulic acid-glucuronide, syringic acid, and hippuric acid (R² = 0.807, p < 0.001). These findings demonstrate that the addition of easily achievable quantities of BB to the diets of older adults significantly alters levels of circulating phenolic compounds which are related to improvements in cognition.

Effects of partial- or whole-body exposures to 56Fe particles on brain function and cognitive performance in rats

On exploratory class missions, such as a mission to Mars, astronauts will be exposed to particles of high energy and charge (HZE particles). Exposure to HZE particles produces changes in neuronal function and can disrupt cognitive performance. Cells throughout the entire body, not just the brain, will be impacted by these particles. To determine the possible effects that irradiation of the body might have on neuronal function and cognitive performance, rats were given head-only, body-only or whole-body exposures to ⁵⁶Fe particles. Cognitive performance (novel object recognition, operant responding) was tested in one set of animals; changes in brain function (oxidative stress, neuroinflammation) was tested in a second set of rats. The results indicated that there were no consistent differences in either behavioral or neurochemical endpoints as a function of the location of the irradiation. These results suggest that radiation to the body can impact the brain, therefore it may be necessary to re-evaluate the estimates of the risk of HZE particle-induced changes in neuronal function and cognitive performance.

Supplementation with a Novel Combination of Fruits and Vegetables Prevented High Fat Diet-Induced Cognitive Impairment in Mice

Objectives

Dementia and cognitive decline are typical age-related neurological disorders. However, obesity has been linked to premature senescence manifestations in various systems including the central nervous system. Nutritional interventions play a role in curbing obesity-associated disorders. Epidemiological studies suggest that increased consumption of fruits and vegetables (F&V) is associated with a reduced risk of cognitive impairment and dementia. The objective of this study was to investigate the causal role of F&V consumption in prevention of high fat diet-induced cognitive impairment in mice.

Methods

Freeze-dried powder of a mixture of 24 F&V was added into the animal diets. Male C57BL/6 J mice (6 wk) were randomly assigned to one of the three diet groups (12/group): low fat (LF, 10% kcal fat), high fat (HF, 45% kcal fat), and HF plus 15% F&V (HF + F&V). The novel object recognition test was used to evaluate cognitive function at 17 weeks. After 20 weeks, mice were euthanized. Blood and liver were collected and biochemical variables and gene expression levels were determined. Fecal microbiota was characterized by 16S rRNA sequencing.

Results

Compared to the LF group, mice fed the HF diet for 17 weeks had significant cognitive impairment. F&V supplementation significantly reduced the HF diet-induced cognitive impairment. Further, compared to mice fed the LF diet, those fed the HF diet had significantly higher levels of liver lipid peroxides (measured as MDA), and circulating pro-inflammatory cytokines and sphingolipid ceramides, all of which are known to contribute to neuroinflammation and cognitive deficits. These HF diet-induced adverse effects were significantly reduced in mice fed the HF + F&V diet. In addition, F&V supplementation alleviated HF diet-induced gut dysbiosis and greatly reduced abundance of some of the bacteria associated with inflammation.

Conclusions

This study provides evidence for the causal role of F&V intake in preventing high fat diet-induced cognition impairment in mice. The beneficial effects of F&V supplementation in improving cognitive function might be due to F&V-induced changes in gut dysbiosis, inflammatory cytokines, and ceramides.

Funding Sources

This material is based upon work supported by the U.S. Department of Agriculture — Agricultural Research Service (ARS), under Agreement No. 58-1950-4-003.

Beneficial Effects of Blueberry Extracts on Adult Human Neural Progenitor Cells

Objectives

Aging-induced declines in neurogenesis and stem cell functions play a key role in the pathophysiology of age-associated neuronal disorders, and oxidative stress and inflammation are the major contributing factors. Blueberries, rich in polyphenols, have been shown to decrease oxidative stress, inflammation, and improve cognitive function in aged animals and humans. The current study investigated the effects of blueberry (BB) treatments on the viability, proliferation, fate choice, and expression of oxidative stress and inflammation markers of adult human neural progenitor cells (AHNPs), to establish mechanisms underlying the beneficial effects.

Methods

AHNPs derived from control and Parkinson's disease (PD) patients were pre-treated with various concentrations of freeze-dried BB extract for 7–10 days. Their viability and proliferation were examined using Trypan Blue exclusion and ethynyl-deoxyuridine (EdU) assay, respectively. Some treated cells were labeled with neuronal markers to examine their differentiation. Expression of oxidative stress and inflammation markers such as iNOS and Nox-2 was evaluated using western blot analysis. Whether BB could protect AHNPs from stress induced by dopamine (DA) was investigated by exposing cells to DA for 2–4 hours prior to evaluating their viability, proliferation, calcium buffering, and expression of oxidative stress and inflammation markers.

Results

Our data show that while BB treatment did not significantly affect the viability of control- and PD-AHNPs, BB extract significantly increased the proliferation rate of PD-AHNPs at higher concentrations. Additionally, BB treatment was able to revive the decrease in cell viability and proliferation following cellular stress induced by DA, indicating a potential neuroprotective effect. BB treatment was also able to protect against the harmful effects on Ca2+ buffering and reduce the increased expression levels of both iNOS and Nox-2 induced by DA exposure.

Conclusions

Blueberry extracts confer anti-oxidative, anti-inflammatory and neuroprotective effects on control and Parkinson's AHNPs, suggesting a role for dietary nutrients in helping to slow progression of neural dysfunction and neurodegenerative disease during aging.

Funding Sources

Supported by USDA/ARS intramural grant, and the Robert and Margaret Patricelli Family Foundation.

Dietary Starch Composition Effects on Cx43-intercellular Communication Channels and Short-Term Memory

Objectives

Intercellular communication mediated by gap junctions is critical for cognitive and sensory functions and is disturbed with age and age-related diseases. We analyzed the impact of consuming a high glycemic diet or a low glycemic dietary intervention on Cx43, a component of gap junction intercellular communication channels associated with spatial short-term memory, in different age groups of mice.

Methods

Male C57Bl6/J mice (n = 12–13) aged 7 months were fed equal amounts of either a high glycemic (HG) diet or a low glycemic (LG) diet for 1 month or 9 months. Within the 9-month feeding trial, half of the HG-fed animals were switched to the LG diet (HGxLG) at 4.5 months. The diets are isocaloric, but the HG starch is 100% composed of amylopectin, and the LG diet contains a 30% amylopectin/70% amylose mixture of starch and is digested much slower. We also analyzed tissues from a previous feeding trial where 12-month aged animals were fed these same diets over 12 months. The animals were weighed weekly, underwent intraperitoneal glucose tolerance tests to evaluate glycemic response, were tested for cognition using a novel object recognition test, and tissues were collected. Tissues including brain and eye samples were evaluated for Cx43, a component of gap junction intercellular communication channels, using immunohistochemistry and western blotting.

Results

At both time points, compared to the LG-fed controls, the HG-fed animals had significantly increased (&gt;10%) body weight, while the HGxLG crossover animals’ body weight did not differ significantly from the LG-fed controls at 15 months. At 14 months, there was no significant difference in novel object recognition, although there was a trend of improved novel object recognition in the HGxLG crossover group. Cx43 gap junction protein accumulated in eye tissues of the HG-fed animals, and this accumulation was attenuated in the HGxLG group.

Conclusions

These results suggest that detrimental consequences of a high glycemic diet during aging on cognitive function may be reversible, supporting that a switch in dietary habits may be an effective nutritional intervention in older adults.

Funding Sources

USDA JM HNRCA Pilot Grant Program, NIH, USDA NIFA, USDA, Thome Memorial Foundation, and the BrightFocus Foundation.

The effects of blueberry and strawberry serum metabolites on age-related oxidative and inflammatory signaling in vitro

Berry fruits contain a variety of bioactive polyphenolic compounds that exhibit potent antioxidant and anti-inflammatory activities. We have shown that consumption of freeze-dried whole berry powder, equivalent to 1 cup per day of blueberry (BB) or 2 cups per day of strawberry (SB), can differentially improve some aspects of cognition in healthy, older adults, compared to placebo-supplemented controls. We investigated whether fasting and postprandial serum from BB- or SB-supplemented older adults (60-75 years), taken at baseline or after 45 or 90 days of supplementation, would reduce the production of inflammatory and oxidative stress markers compared to serum from a placebo group, in LPS-stressed HAPI rat microglial cells, in vitro. Serum from both BB- and SB-supplemented participants reduced nitrite production, iNOS and COX-2 expression, and TNF-alpha release relative to serum from placebo controls (p < 0.05). Protection was greatest with serum from the 90-day time-point, suggesting that ongoing supplementation may provide the most health benefits. Serum was protective in both fasted and postprandial conditions, indicating that the effects are not only acute and that the meal did not challenge subjects' ability to regulate oxidative and inflammatory stress. These results suggest that berry metabolites, present in the circulating blood following ingestion, may be mediating the anti-inflammatory effects of dietary berry fruit.

Effects of exposure to 12C and 4He particles on cognitive performance of intact and ovariectomized female rats

Exposure to the types of radiation encountered outside the magnetic field of the earth can disrupt cognitive performance. Exploratory class missions to other planets will include both male and female astronauts. Because estrogen can function as a neuroprotectant, it is possible that female astronauts may be less affected by exposure to space radiation than male astronauts. To evaluate the effectiveness of estrogen to protect against the disruption of cognitive performance by exposure to space radiation intact and ovariectomized female rats with estradiol or vehicle implants were tested on novel object performance and operant responding on an ascending fixed-ratio reinforcement schedule following exposure to ¹²C (290 MeV/n) or ⁴He (300 MeV/n) particles. The results indicated that exposure to carbon or helium particles did not disrupt cognitive performance in the intact rats. Estradiol implants in the ovariectomized subjects exacerbated the disruptive effects of space radiation on operant performance. Although estrogen does not appear to function as a neuroprotectant following exposure to space radiation, the present data suggest that intact females may be less responsive to the deleterious effects of exposure to space radiation on cognitive performance, possibly due to the effects of estrogen on cognitive performance.

Protective Effects of Foods Containing Flavonoids on Age-Related Cognitive Decline

PURPOSE OF REVIEW

Evidence suggests that flavonoids, polyphenolic compounds found in many plant-derived foods, such as berries, may allay cognitive impairment. We review recent research exploring the protective effects of flavonoids on age-related cognitive decline and neurodegenerative disorders in humans and animals. We also address the mechanisms by which flavonoids may exert their effects and promising avenues of future research.

RECENT FINDINGS

Flavonoids have been found to decrease neuroinflammation, reduce oxidative stress, and mediate neuroplasticity in animal models of neurodegeneration and aging. Injecting flavonoids encased in metal nanoparticles may further enhance the efficacy of flavonoids. Animal studies also demonstrate that flavonoid supplementation may alleviate neurodegenerative cognitive and memory impairments. Limited human studies, however, demonstrate the need for further clinical research investigating flavonoids. Flavonoid supplementation, as well as dietary modification to include whole foods high in flavonoids, may provide therapeutic potential for aging individuals experiencing cognitive deficits resulting from neurodegeneration.

Blueberries Improve Neuroinflammation and Cognition differentially Depending on Individual Cognitive baseline Status

Daily supplementation of blueberries (BBs) reverses age-related deficits in behavior in aged rats. However, it is unknown whether BB is more beneficial to one subset of the population dependent on baseline cognitive performance and inflammatory status. To examine the effect of individual differences on the efficacy of BB, aged rats (17 months old) were assessed for cognition in the radial arm water maze (RAWM) and divided into good, average, and poor performers based on navigation errors. Half of the rats in each cognitive group were then fed a control or a 2% BB diet for 8 weeks before retesting. Serum samples were collected, pre-diet and post-diet, to assess inflammation. Latency in the radial arm water maze was significantly reduced in the BB-fed poor performers (p < .05) and preserved in the BB-fed good performers. The control-fed good performers committed more working and reference memory errors in the post-test than pretest (p < .05), whereas the BB-fed good performers showed no change. An in vitro study using the serum showed that BB supplementation attenuated lipopolysaccharide (LPS)-induced nitrite and tumor necrosis factor-alpha, and cognitive performance was associated with innate anti-inflammatory capability. Therefore, consumption of BB may reverse some age-related deficits in cognition, as well as preserve function among those with intact cognitive ability.

Polyphenol Consumption on Human Bile Acids Metabolism: Preliminary Data of Bile Acid Profiles in Human Biological Samples (P06-131-19)

Objectives

Bile acids (BAs) play a critical role in regulating human health through the activation of BAs receptor farnesoid X receptor (FXR) and membrane G protein coupled bile acid receptor-1 (TGR5). We aimed to develop methods to characterize BAs and their metabolites in human biological samples and characterize changes in BAs profile after chronic polyphenol consumption to help guide investigations on the potential health effects of polyphenols via BAs metabolism.

Methods

Plasma, fecal and urine samples from two human studies that included berry intake were used for developing qualitative analysis of BAs using ultra high-performance liquid chromatography (UHPLC) coupled with electrospray ionization quadrupole time of flight (QTOF). The compounds were identified based on the exact mass, fragmentation pattern, available reference standards and database search. To investigate the effect of chronic polyphenol consumption on BAs composition, pooled plasma samples (fasting and postprandial 2 h, n = 6) from a chronic (45 and 90 days) strawberry supplementation study (24 g freeze dried/day) with an older population were analyzed.

Results

Among 106 BAs and their metabolites which were tentatively identified in the samples used for method development, 70, 55, and 47 BAs species were characterized in plasma, feces and urine samples, respectively. The qualitative analysis of BAs in plasma samples from subjects following the strawberry consumption protocol detected 8 primary and 31 secondary BAs. After 90-days strawberry supplementation, two secondary BAs–glycolithocholic acid and 9(11), (5β)-cholenic acid-3α, 12α-diol were decreased to undetectable levels in the pooled fasting sample and the FRX/TGR5 agonists, including chenodeoxycholic acid, deoxycholic acid, cholic acid, glycodeoxycholic acid and taurocholic acid, showed increasing peak areas at 2 h postprandial compared to fasting.

Conclusions

The changes in BAs profiles in fasting and postprandial plasma samples after chronic strawberry feeding suggest that strawberry polyphenols may alter BAs metabolism and the FXR/TGR5 signaling.

Funding Sources

This work was funded by the California Strawberry Commission, USDA Intramural Funds and various donor funds to the Center for Nutrition Research, IIT.

Effects of head-only or whole-body exposure to very low doses of 4He (1000 MeV/n) particles on neuronal function and cognitive performance

On exploratory class missions, astronauts will be exposed to a range of heavy particles which vary in linear energy transfer (LET). Previous research has shown a direct relationship between particle LET and cognitive performance such that, as particle LET decreases the dose needed to affect cognitive performance also decreases. Because a significant portion of the total dose experienced by astronauts may be expected to come from exposure to low LET ⁴He particles, it would be important to establish the threshold dose of ⁴He particles that can produce changes in cognitive performance. The results indicated that changes in neuronal function and cognitive performance could be observed following both head-only and whole-body exposures to ⁴He particles at doses as low as 0.01-0.025 cGy. These results, therefore, suggest the possibility that astronauts on exploratory class missions may be at a greater risk for HZE-induced deficits than previously anticipated.

Metabolic fate of strawberry polyphenols after chronic intake in healthy older adults

Strawberries contain a wide array of nutrients and phytochemicals including polyphenols such as anthocyanins, proanthocyanidins and ellagitannins. These polyphenols are absorbed and metabolized to various phenolic metabolites/conjugates in the body, which may play a role in disease risk reduction. In the present study, we investigated the metabolic fate of strawberry polyphenols after chronic (90 days) supplementation of freeze-dried strawberry (24 g d^-1, equivalent to 2 cups of fresh strawberries) vs. control powder in 19 healthy older adults. Blood samples were collected at two time-points i.e., fasting (t = 0 h) and 2 h after the breakfast meal. On days 45 and 90 breakfast also included a control or strawberry drink consistent with their treatment randomization. A total of 21 polyphenolic metabolites were quantified in plasma consisting of 3 anthocyanins/metabolites, 3 urolithin metabolites and 15 phenolic acid metabolites. Among anthocyanins/metabolite, pelargonidin glucuronide (85.7 ± 9.0 nmol L^-1, t = 2 h, day 90) was present in the highest concentration. Persistent concentrations of anthocyanins/metabolites, urolithins and some phenolic acids were observed in fasting (t = 0 h) plasma samples on day 45 and 90 after strawberry drink consumption suggesting a role of enteric, enterohepatic recycling or upregulation of gut microbial and/or human metabolism of these compounds. Our results suggest that strawberry polyphenols are absorbed and extensively metabolized, and can persist in the circulation.

Raspberry differentially improves age-related declines in psychomotor function dependent on baseline motor ability

Among older adults, falls are a leading cause of distress, pain, injury, loss of confidence, and ultimately, loss of independence and death. Previous studies in our laboratory have demonstrated that berry supplementation improves the age-related declines in balance, muscle strength, and coordination that often lead to falls, even when initiated later in life. The purpose of this study was to explore the interaction between baseline motor performance and the daily intake of raspberry required to improve/preserve motor function. Aged male F344 (17 mo) rats were tested for baseline (pre-test) balance, muscle strength, and coordination, and divided into good, average, and poor performers based on their motor composite score. Rats in each category were fed with either a control, 1%, or 2% raspberry-supplemented diet for 8 weeks and then retested (post-test). Poor performers fed with 1% or 2% raspberry had higher post-test composite scores (p < 0.05), while 2% raspberry lowered post-test composite scores in the good performers (p < 0.05), compared to control-fed rats. 1% and 2% raspberry appeared to preserve the performance of good performers and improve the performance of poor performers on plank walking (p < 0.05), while 2% raspberry improved post-test grip strength of the poor performers (p < 0.05). Additionally, rats with lower post-diet composite scores had higher levels of serum IL-1β levels (r = -0.347, p < 0.05). These findings identified poor performers as being the most likely to benefit from daily consumption of ½-2 cups of raspberry to improve/preserve motor function. Therefore, increased raspberry consumption may reduce fall risk, extend independence, and improve quality of life in the aging population.

Age as a factor in the responsiveness of the organism to the disruption of cognitive performance by exposure to HZE particles differing in linear energy transfer

Exposure to particles of high energy and charge (HZE particles) can produce decrements in cognitive performance. A series of experiments exposing rats to different HZE particles was run to evaluate whether the performance decrement was dependent on the age of the subject at the time of irradiation. Fischer 344 rats that were 2-, 11- and 15/16-months of age were exposed to ¹⁶O, ⁴⁸Ti, or ⁴He particles at the NASA Space Radiation Laboratory at Brookhaven National Laboratory. As previously observed following exposure to ⁵⁶Fe particles, exposure to the higher LET ⁴⁸Ti particles produced a disruption of cognitive performance at a lower dose in the older subjects compared to the dose needed to disrupt performance in the younger subjects. There were no age related changes in the dose needed to produce a disruption of cognitive performance following exposure to lower LET ¹⁶O or ⁴He particles. The threshold for the rats exposed to either ¹⁶O or ⁴He particles was similar at all ages. Because the 11- and 15-month old rats are more representative of the age of astronauts (45-55 years old) the present results indicate that particle LET may be a critical factor in estimating the risk of developing a cognitive deficit following exposure to space radiation on exploratory class missions.

Walnut extract modulates activation of microglia through alteration in intracellular calcium concentration

Diets supplemented with walnuts have shown to protect brain against oxidative and inflammatory cytotoxicity and promote protective cellular and cognitive function. The current study was undertaken to test the hypothesize that whole walnut extract (WNE) inhibits lipopolysaccharide (LPS)-induced microglial activation by regulating calmodulin (CaM) expression through [Ca²⁺]_i. To test this hypothesis, we used an in vitro model the highly aggressively proliferating immortalized cells, a rat microglial cell line, treated with various concentrations of WNEs. Treatment with WNE (1.5%, 3%, or 6%) induced a slow rise in intracellular calcium in a concentration- and time-dependent manner, and this rise became exaggerated when cells were depolarized with potassium chloride (100 mmol/L). Cells treated with WNE (1%, 3%, or 6%) upregulated CaM protein levels, with 1 hour posttreatment being the peak time, regardless of WNE concentration. Interestingly, this WNE-induced upregulation of CaM was blocked by pretreatment with thapsigargin. Additionally, treatment with WNE (1%, 3%, or 6%) 1 hour prior to LPS treatment was found to be effective in preventing LPS-induced upregulation of inducible nitric oxide synthase expression, upregulation of ionized Ca²⁺-binding adaptor-1, and downregulation of CaM. These findings suggest that bioactive compounds in walnut are capable of modulating microglial activation through regulation of intracellular calcium and CaM expression. Nutritional interventions using walnuts may be effective in the amelioration of chronic inflammation and neurodegeneration.

Nutritional Factors Affecting Adult Neurogenesis and Cognitive Function

Adult neurogenesis, a complex process by which stem cells in the hippocampal brain region differentiate and proliferate into new neurons and other resident brain cells, is known to be affected by many intrinsic and extrinsic factors, including diet. Neurogenesis plays a critical role in neural plasticity, brain homeostasis, and maintenance in the central nervous system and is a crucial factor in preserving the cognitive function and repair of damaged brain cells affected by aging and brain disorders. Intrinsic factors such as aging, neuroinflammation, oxidative stress, and brain injury, as well as lifestyle factors such as high-fat and high-sugar diets and alcohol and opioid addiction, negatively affect adult neurogenesis. Conversely, many dietary components such as curcumin, resveratrol, blueberry polyphenols, sulforaphane, salvionic acid, polyunsaturated fatty acids (PUFAs), and diets enriched with polyphenols and PUFAs, as well as caloric restriction, physical exercise, and learning, have been shown to induce neurogenesis in adult brains. Although many of the underlying mechanisms by which nutrients and dietary factors affect adult neurogenesis have yet to be determined, nutritional approaches provide promising prospects to stimulate adult neurogenesis and combat neurodegenerative diseases and cognitive decline. In this review, we summarize the evidence supporting the role of nutritional factors in modifying adult neurogenesis and their potential to preserve cognitive function during aging.

Blueberry supplementation attenuates microglia activation and increases neuroplasticity in mice consuming a high-fat diet

OBJECTIVES

Consuming a high-fat diet (HFD) may result in behavioral deficits similar to those observed in aging animals. Blueberries may prevent and even reverse age-related alterations in neurochemistry and behavior. It was previously demonstrated that middle-aged mice fed HFD had impaired memory; however, supplementation of HFD with blueberry reduced these memory deficits. As a follow-up to that study, the brain tissue from HFD-fed mice with and without blueberry supplementation was assessed to determine the neuroprotective mechanism(s) by which blueberry allayed cognitive dysfunction associated with HFD.

METHODS

Mice were fed HFDs (60% calories from fat) or low-fat diets (LFD) with and without 4% blueberry (freeze-dried, U.S. Highbush Blueberry Council). Microglia activation was assessed ex vivo and in vitro. The hippocampus was assessed for brain-derived neurotrophic factor (BDNF) and neurogenesis by measuring doublecortin (DCX).

RESULTS

There was significantly less microglia ionized calcium binding adaptor molecule 1 staining and fewer microglia in the brains of mice fed HFD + blueberry compared to mice fed LFD and HFD. BV-2 microglial cells treated with serum collected from the mice fed the diets supplemented with blueberry produced less nitric oxide compared to cells treated with serum from mice fed HFD. BDNF levels were higher and the number of DCX-positive cells was greater in the hippocampus of mice fed HFD + blueberry compared to mice fed HFD.

DISCUSSION

This study demonstrated that supplementation of a HFD with blueberry reduced indices of microglia activation and increased neuroplasticity, and these changes may underlie the protection against memory deficits in HFD-fed mice supplemented with blueberry.

A Clinically Relevant Frailty Index for Aging Rats

Frailty is a clinical syndrome that is increasingly prevalent during aging. Frailty involves the confluence of reduced strength, speed, physical activity, and endurance and is associated with adverse health outcomes. The present study adapts existing clinical and preclinical indices of frailty to the Fischer (F344) rat. Male F344 rats (n = 133; 17 mo) completed a battery of behavioral tasks, including forelimb wire suspension (strength), rotarod (speed), open field (physical activity), and inclined screen (endurance). Rats that performed poorly (lowest quintile) on two tasks were considered mildly frail (17.29%, n = 23), and rats that performed poorly on 3-4 tasks were considered frail (2.26%, n = 3). Logistic regression of 100-day survival revealed that mildly frail rats were 3.8 times and frail rats were 27.5 times more likely to die during that period than nonfrail rats (p = .038; 95% confidence interval: 2.030, 372.564). The selected criterion tests, cutoff points, and index provide a potential tool for identifying frailty in aged F344 rats, which is consistent with existing frailty indices for humans and mice.

Neurochemical differences in learning and memory paradigms among rats supplemented with anthocyanin-rich blueberry diets and exposed to acute doses of 56Fe particles

The protective effects of anthocyanin-rich blueberries (BB) on brain health are well documented and are particularly important under conditions of high oxidative stress, which can lead to "accelerated aging." One such scenario is exposure to space radiation, consisting of high-energy and -charge particles (HZE), which are known to cause cognitive dysfunction and deleterious neurochemical alterations. We recently tested the behavioral and neurochemical effects of acute exposure to HZE particles such as ⁵⁶Fe, within 24-48h after exposure, and found that radiation primarily affects memory and not learning. Importantly, we observed that specific brain regions failed to upregulate antioxidant and anti-inflammatory mechanisms in response to this insult. To further examine these endogenous response mechanisms, we have supplemented young rats with diets rich in BB, which are known to contain high amounts of antioxidant-phytochemicals, prior to irradiation. Exposure to ⁵⁶Fe caused significant neurochemical changes in hippocampus and frontal cortex, the two critical regions of the brain involved in cognitive function. BB supplementation significantly attenuated protein carbonylation, which was significantly increased by exposure to ⁵⁶Fe in the hippocampus and frontal cortex. Moreover, BB supplementation significantly reduced radiation-induced elevations in NADPH-oxidoreductase-2 (NOX2) and cyclooxygenase-2 (COX-2), and upregulated nuclear factor erythroid 2-related factor 2 (Nrf2) in the hippocampus and frontal cortex. Overall results indicate that ⁵⁶Fe particles may induce their toxic effects on hippocampus and frontal cortex by reactive oxygen species (ROS) overload, which can cause alterations in the neuronal environment, eventually leading to hippocampal neuronal death and subsequent impairment of cognitive function. Blueberry supplementation provides an effective preventative measure to reduce the ROS load on the CNS in an event of acute HZE exposure.

Tart cherry supplementation improves working memory, hippocampal inflammation, and autophagy in aged rats

High consumption of fruits and vegetables has been associated with reduced risk of debilitating diseases and improved cognition in aged populations. These beneficial effects have been attributed to the phytochemicals found in fruits and vegetables, which have previously been shown to be anti-inflammatory and modulate autophagy. Tart cherries contain a variety of potentially beneficial phytochemicals; however, little research has been done to investigate the effects of tart cherry on the aging brain. Therefore, the purpose of this study was to determine if tart cherry supplementation can improve cognitive and motor function of aged rats via modulation of inflammation and autophagy in the brain. Thirty 19-month-old male Fischer 344 rats were weight-matched and assigned to receive either a control diet or a diet supplemented with 2 % Montmorency tart cherry. After 6 weeks on the diet, rats were given a battery of behavioral tests to assess for strength, stamina, balance, and coordination, as well as learning and working memory. Although no significant effects were observed on tests of motor performance, tart cherry improved working memory of aged rats. Following behavioral testing, the hippocampus was collected for western/densitometric analysis of inflammatory (GFAP, NOX-2, and COX-2) and autophagy (phosphorylated mTOR, Beclin 1, and p62/SQSTM) markers. Tart cherry supplementation significantly reduced inflammatory markers and improved autophagy function. Daily consumption of tart cherry reduced age-associated inflammation and promoted protein/cellular homeostasis in the hippocampus, along with improvements in working memory. Therefore, addition of tart cherry to the diet may promote healthy aging and/or delay the onset of neurodegenerative diseases.

Serum metabolites from walnut-fed aged rats attenuate stress-induced neurotoxicity in BV-2 microglial cells

The shift in equilibrium towards excess reactive oxygen or nitrogen species production from innate antioxidant defenses in brain is a critical factor in the declining neural function and cognitive deficit accompanying age. Previous studies from our laboratory have reported that walnuts, rich in polyphenols, antioxidants, and omega fatty acids such as alpha-linolenic acid and linoleic acid, improve the age-associated declines in cognition and neural function in rats. Possible mechanisms of action of these effects include enhancing protective signaling, altering membrane microstructures, decreasing inflammation, and preventing accumulation of polyubiquitinated protein aggregates in critical regions of the brain. In the current study, we investigated whether the serum collected from aged animals fed with walnut diets (0, 6, and 9%, w/w) would enhance protection on stressed BV-2 microglia in vitro. In the growth medium, fetal bovine serum was substituted with the serum collected from 22-month-old rats fed per protocol for 12 weeks. Walnut diet serum (6 and 9%) significantly attenuated lipopolysaccharide-induced nitrite release compared to untreated control cells and those treated with serum from rats fed 0% walnut diets. The results also indicated a significant reduction in pro-inflammatory tumor necrosis factor-alpha, cyclooxygenase-2, and inducible nitric oxide synthase. These results suggest antioxidant and anti-inflammatory protection or enhancement of membrane-associated functions in brain cells by walnut serum metabolites.

Modulation of oxidative stress, inflammation, autophagy and expression of Nrf2 in hippocampus and frontal cortex of rats fed with açaí-enriched diets

OBJECTIVE

Açaí (Euterpe spp.), an exotic palm fruit, has recently emerged as a promising source of natural antioxidants with wide pharmacological and nutritional value. In this study, two different species of açaí pulp extracts, naturally grown in two distinct regions of the Amazon, namely, Euterpe oleracea Mart. (habitat: Brazilian floodplains of the Amazon) and Euterpe precatoria Mart. (habitat: Bolivian Amazon), were studied for their effects on brain health and cognition.

METHODS

Neurochemical analyses were performed in critical brain regions associated with memory and cognition of 19-month-old açaí-fed rats, in whom the cognitive benefits of açaí had been established.

RESULTS

Results indicated significant reductions (P< 0.05) in prooxidant NADPH-oxidoreductase-2 (NOX2) and proinflammatory transcription factor NF-κB in açaí-fed rats. Measurement of Nrf2 expression, a transcription factor for antioxidant enzymes, and a possible link between oxidative stress, neuroinflammation and autophagy mechanisms, indicated significant overexpression (P<0.005) in the hippocampus and frontal cortex of the açaí-fed rats. Furthermore, significant activation of endogenous antioxidant enzymes GST and SOD were also observed in the açaí-fed animals when compared to control. Analysis of autophagy markers such as p62, phospho-mTOR, beclin1 and MAP1B-LC3 revealed differential expression in frontal cortex and hippocampus, mostly indicating an upregulation in the açaí-fed rats.

DISCUSSION

In general, results were more profound for EP than EO in hippocampus as well as frontal cortex. Therefore, an açaí-enriched diet could possibly modulate Nrf2, which is known to modulate the intracellular redox status, thereby regulating the ubiquitin-proteosomal pathway, ultimately affecting cognitive function in the aging brain.

Lack of reliability in the disruption of cognitive performance following exposure to protons

A series of three replications were run to determine the reliability with which exposure to protons produces a disruption of cognitive performance, using a novel object recognition task and operant responding on an ascending fixed-ratio task. For the first two replications, rats were exposed to head-only exposures to 1000 MeV/n protons at the NASA Space Radiation Laboratory. For the third replication, subjects were given head-only or whole-body exposures to both 1000 and 150 MeV/n protons. The results were characterized by a lack of consistency in the effects of exposure to protons on the performance of these cognitive tasks, both within and between replications. The factors that might influence the lack of consistency and the implications for exploratory class missions are discussed.

Effects of pterostilbene and resveratrol on brain and behavior

Age is the greatest universal risk factor for neurodegenerative diseases. During aging, these conditions progress from minor loss of function to major disruptions in daily life, loss of independence and ultimately death. Because approximately 25% of the world population is expected to be older than age 65 by 2050, and no treatments exist to halt or reverse ongoing neurodegeneration, the need for effective prevention strategies is more pressing that ever before. A growing body of research supports the role of diet in healthy aging, particularly diets rich in bioactive phytochemical compounds. Recently, stilbenes such as resveratrol (3, 5, 4'-trans-trihydroxystilbene) and its analogue, pterostilbene, have gained a significant amount of attention for their potent antioxidant, anti-inflammatory, and anticarcinogenic properties. However, evidence for the beneficial effects of stilbenes on cerebral function is just beginning to emerge. In this review, we summarize the current knowledge on the role of resveratrol and pterostilbene in improving brain health during aging, with specific focus on antioxidant and anti-inflammatory signaling and behavioral outcomes.

Cerebral blood volume and vasodilation are independently diminished by aging and hypertension: a near infrared spectroscopy study

BACKGROUND

Senescent changes in brain microvascular circulation may cause or contribute to age-related cognitive decline. Such changes are promoted partly by aging, but also by chronic hypertension, a leading treatable cause of cognitive decline.

OBJECTIVES

We aimed to non-invasively detect in vivo the senescent changes in brain microvascular circulation associated with age and hypertension, and inquired whether decrements driven by aging would be exacerbated by chronic hypertension.

METHODS

In this longitudinal study, absolute near infrared spectroscopy (NIRS) was used to quantify in vivo cerebral blood volume (CBV) and assess the hemodynamic response to a hypercapnic respiratory challenge in normotensive Wistar-Kyoto (WKY) and spontaneous-hypertensive (SHR) rats. The impact of age and hypertension were evaluated by repeating these measurements on the same animals at 4- and 16-months of age.

RESULTS

CBV decreased markedly with age in both strains, from 4.5 ± 0.2 to 2.6 ± 0.1 ml/100g tissue, on average. Chronic hypertension, however, did not significantly exacerbate this age-related decrease in CBV (-48.1 ± 3.7% in WKYs versus -53.3 ± 5.4% in SHRs). In contrast, vasoreactivity was already impaired in the young hypertensive rats (ΔVMR 0.017 ± 0.014 in young SHRs versus 0.042 ± 0.005 in young WKYs) and further worsened by middle-age (ΔVMR 0.011 ± 0.017 middle-aged SHRs).

CONCLUSION

Whereas a decrease in brain blood volume correlated with age but not hypertension, vasodilatory capacity was diminished due to hypertension but did not appear affected by age alone. The ability of absolute NIRS to distinguish between such senescent changes in brain (micro)vascular circulation in life may allow early detection and intervention to preserve cerebrovascular health with age.