Oxytocin and elderly MRI-based hippocampus and amygdala volume: a 7-year follow-up study

Association between sTREM2, an immune biomarker of microglial activation, and frontal lobe function in community-dwelling older adults: a cross-sectional study

Objective: Identifying the peripheral biomarkers related to the prevention or modification of unhealthy mental conditions in older adults is extremely beneficial. This study aimed to evaluate the serum levels of soluble triggering receptor expressed on myeloid cells 2 (sTREM2), a soluble form of an innate immune receptor expressed on microglia, in older adults living in a rural community, and their association with cognitive function. Materials and Methods: This survey was conducted between November 2016 and September 2017 in Kurokawa-cho, Imari, Saga Prefecture, Japan, among people aged ≥65 years. Blood samples were collected from the participants for serum sTREM2 level analysis using a peptide enzyme immunoassay. The participants underwent cognitive function assessments, including the Mini-Mental State Examination, Clinical Dementia Rating, and Frontal Assessment Battery. Therefore, we examined the association between serum sTREM2 levels and cognitive function. Results: Of the 95 participants, 25 were men and 70 were women with a mean age 78.24 ± 3.85 years and 77.96 ± 5.52 years, respectively. Serum sTREM2 levels were negatively associated with Frontal Assessment Battery scores, even after adjusting for age, sex, years of education, and serum high-sensitivity C-reactive protein levels. Conclusion: Serum sTREM2 levels may be associated with frontal lobe function in adults aged ≥65 years.

Association depressive symptoms with memory function and social capital before and during COVID-19 in community-dwelling older adults in rural Japan: A retrospective study with a longitudinal data

OBJECTIVES

This study aimed to investigate the impact of memory function and social capital on depressive symptoms during the COVID-19 pandemic among older adults in rural Japan.

METHODS

A retrospective study with longitudinal data was conducted during COVID-19 from May 2021 to November 2021 (T2) in Kurogawa, Japan. The candidate population for this study was 145 with the following requirements: (1) older individuals aged 65 years or above who were registered in the Kurogawa study, and (2) those with previous data (from November 2016 to February 2020; T1 as pre-pandemic). Memory function was assessed using the Wechsler Memory Scale-Revised Logical Memory II delayed recall part A (LM II-DR). Depressive symptoms were assessed using the Japanese version of the 15-item Geriatric Depression Scale (GDS-15). Social capital was evaluated through civic participation, social cohesion, and reciprocity. Fear of the COVID-19 infection (FCV-19S) was evaluated.

RESULTS

The final analysis included 96 participants (mean age = 81.0 years, SD = 4.8) Multivariate analysis for GDS-15 score by Mixed Model Repeated Measures (MMRM) revealed significant associations between LM II-DR (β = -0.13, 95% CI: -0.21-0.05, p = 0.002) and FCV-19S during COVID-19 (β = 0.08, 95% CI: 0.01-0.15, p = 0.02) with GDS-15 score. However, civic participation, social cohesion and reciprocity were not associated with GDS-15 score.

CONCLUSIONS

Among older adults in rural Japan, memory function and fear of the COVID-19 infection were significantly associated with depressive symptoms in MMRM analysis. However, social capital was not associated with depressive symptoms. This highlights the need to address memory function and fear of the COVID-19 infection in interventions for older adults during crises like the COVID-19 pandemic.

Negative Stressful Life Events and Social Support Are Associated With White Matter Integrity in Depressed Patients and Healthy Control Participants: A Diffusion Tensor Imaging Study

BACKGROUND

Negative stressful life events and deprivation of social support play critical roles in the development and maintenance of major depressive disorder (MDD). The present study aimed to investigate in a large sample of patients with MDD and healthy control participants (HCs) whether these effects are also reflected in white matter (WM) integrity.

METHODS

In this diffusion tensor imaging study, 793 patients with MDD and 793 age- and sex-matched HCs were drawn from the Marburg-Münster Affective Disorders Cohort Study (MACS) and completed the Life Events Questionnaire (LEQ) and Social Support Questionnaire (SSQ). Generalized linear models were performed to test voxelwise associations between fractional anisotropy (FA) and diagnosis (analysis 1), LEQ (analysis 2), and SSQ (analysis 3). We examined whether SSQ interacts with LEQ on FA or is independently associated with improved WM integrity (analysis 4).

RESULTS

Patients with MDD showed lower FA in several frontotemporal association fibers compared with HCs (pTFCE-FWE = .028). Across both groups, LEQ correlated negatively with FA in widely distributed WM tracts (pTFCE-FWE = .023), while SSQ correlated positively with FA in the corpus callosum (pTFCE-FWE = .043). Modeling the combined association of both variables on FA revealed significant-and antagonistic-main effects of LEQ (pTFCE-FWE = .031) and SSQ (pTFCE-FWE = .037), but no interaction of SSQ × LEQ.

CONCLUSIONS

Our results indicate that negative stressful life events and social support are both related to WM integrity in opposing directions. The associations did not differ between patients with MDD and HCs, suggesting more general, rather than depression-specific, mechanisms. Furthermore, social support appears to contribute to improved WM integrity independent of stressful life events.

Comparison of plasma oxytocin level in women with natural and surgical menopause

OBJECTIVE

We aimed to investigate plasma oxytocin level in women with natural and surgical menopause and its relation with other metabolic parameters.

METHODS

This study included 89 postmenopausal women admitted to menopausal outpatient clinics and gave written consent to participate. Participants were allocated into natural (Group 1; n = 61) and surgical (Group 2; n = 28) menopause groups based on causative process for the onset of menopause. After the clinical evaluation and physical examination, blood samples are collected for biochemical profile and plasma oxytocin levels. The complete blood count, lipid profile, thyroid panel, blood glucose concentration, vitamin D and liver enzymes were measured by autoanalyzer, plasma oxytocin level was measured spectrophotometrically by ELISA method.

RESULTS

The groups were comparable for age, body mass index, menopause duration, gravity and blood parameters measured except significantly different plasma oxytocin levels between the two groups as 6.8 (3.2-20.6) ng/ml in natural menopause group and 4.2 (2.9-18.2) ng/ml in surgical menopause group (p < 0.001). Plasma oxytocin level was also negatively correlated with age (r = -0.245, p = 0.022) and menopausal duration (r = -0.275, p = 0.01).

CONCLUSION

Our results point out that oxytocin might be a target hormone to manage menopause associated disorders and/or it should be considered for its role in the differences in the incidences of postmenopausal diseases and quality of life in the course of natural and surgical menopausal transition.

Association between serum oxytocin levels and depressive state in community-dwelling older adults: A cross-sectional study

Aim

Identifying peripheral biomarkers related to the prevention or modification of unhealthy mental conditions in older adults would be extremely beneficial. This study aimed to evaluate serum oxytocin levels in older adults living in a rural community and their association with cognitive function, anxiety, depressive state, and well-being.

Methods

This survey was conducted between November 2016 and September 2017 in Kurokawa-cho, Imari, Saga Prefecture, Japan, among people aged ≥65 years. Blood samples were collected from the participants for serum oxytocin level analysis, which was performed using peptide enzyme immunoassay. Participants underwent neuropsychological assessments, including the Mini-Mental State Examination, Clinical Dementia Rating, Frontal Assessment Battery, State-Trait Anxiety Inventory, 15-item Geriatric Depression Scale, and 17-item Philadelphia Geriatric Center Morale Scale. We examined the association between serum oxytocin levels and neuropsychological assessment results.

Results

Out of 94 participants, 25 were men and 69 were women, with mean ages of 78.24 ± 3.85 years and 78.10 ± 5.43 years, respectively. Serum oxytocin levels were negatively associated with 15-item Geriatric Depression Scale scores. Additionally, nondepressive state/depressive state was classified by the 15-item Geriatric Depression Scale (cut-off 5/6). Logistic regression analysis showed that higher serum oxytocin levels tended to be associated with a less depressive state at that time.

Conclusions

Serum oxytocin levels may be associated with depressive state in adults aged ≥65 years.

Salivary 3-methoxy-4-hydroxyphenylglycol and MRI-based volume change of the precuneus in community-dwelling elderly people

BACKGROUND

The noradrenergic systems in the brain maintain cognitive functions including attention/concentration and establishment of long-term memory. In addition, hypofunction of noradrenergic systems is supposed to be involved in the pathophysiology of Alzheimer's disease. In this study, we tried to examine the possible associations of concentrations of basal salivary 3-methoxy-4-hydroxyphenylglycol (sMHPG), a major metabolite of noradrenaline, and brain volume changes during 4 years in elderly people living in a rural community.

METHODS

The survey was conducted twice in Kurokawa-cho, Imari, Saga Prefecture, Japan, among people aged 65 years and older. We collected data from 226 residents. Measurements of sMHPG and brain MRIs were collected at Time 1 (2005-2007). Follow-up brain MRIs were taken at Time 2 (2009-2011). A total of 70 participants (18 men, mean age 71.9 ± 4.8 years; 52 women, mean age 72.0 ± 4.3 years) completed this survey. Concentrations of sMHPG at baseline were divided into two groups using the mean value (12.83 ng/ml). We compared the brain volumes between groups with higher and lower sMHPG concentrations over time using voxel-based morphometry implemented with statistical parametric mapping.

RESULTS

In participants with higher sMHPG concentrations at baseline, brain volumes including right precuneus were significantly larger 4 years after baseline than those with lower sMHPG concentrations at baseline. No interaction between sMHPG concentration and MRI acquisition interval was found.

CONCLUSION

Our results suggest that higher sMHPG concentrations in elderly people might be associated with maintenance of brain volume, especially in brain regions closely related to cognitive function.

Serum oxytocin correlated with later logical memory in older Japanese women: A 7-year follow-up study

Objectives

This study aimed to investigate the longitudinal relationship between serum oxytocin and logical memory among older adults in rural Japan and clarify sex differences in this relationship.

Measurements

The first survey was conducted from October 2009 to March 2011 (Time 1) and the second from November 2016 to September 2017 (Time 2). The final analysis for Time 1 included 385 participants (median age 75 years, interquartile range [IQR] 70-81 years) and that for Time 2 included 76 participants (median age 80 years, IQR 76-83 years). We assessed cognition, logical memory, and living conditions, and measured serum oxytocin levels. Logical memory was evaluated using the Wechsler Memory Scale-Revised Logical Memory II delayed recall part A (LM II-DR). Serum oxytocin was measured using the enzyme immunoassay method.

Results

The median (IQR) oxytocin level among men (n = 20) was 34 (16-78) pg/mL at Time 1 and 53 (28-140) pg/mL at Time 2. The median (IQR) oxytocin level among women (n = 56) was 117 (35-412) pg/mL at Time 1 and 76 (32-145) pg/mL at Time 2. The median oxytocin level among women at Time 2 was significantly lower than that at Time 1 (p = 0.004). The multivariate analysis showed that for women, LM II-DR score at Time 2 was positively associated with oxytocin level at Time 1 (p = 0.042) and negatively associated with age (p = 0.02).

Conclusions

Our study suggests that maintaining high oxytocin levels in older women may prevent age-related decline in logical memory.

Association between cortisol and aging-related hippocampus volume changes in community-dwelling older adults: a 7-year follow-up study

BACKGROUND

Identifying peripheral biomarkers related to modifiable risk factors to prevent dementia at an early stage will be extremely beneficial. We have been studying how older adults can maintain their mental health and continue to live in a familiar community. The aim of this study is to investigate the association between serum cortisol levels and brain volume among older adults in rural Japan.

METHODS

This was a longitudinal study conducted in Kurokawa-cho, Imari, Saga Prefecture, Japan, among people aged 65 years and above, as reported previously. We conducted a survey twice. The first survey was conducted from October 2009 to March 2011 (Timepoint 1) and the second was conducted from November 2016 to September 2017 (Timepoint 2). Blood samples for serum cortisol levels analysis were collected from participants at Timepoint 1. Serum cortisol levels were measured using the enzyme-linked immunosorbent assay. The participants underwent brain MRI examinations, and Mini-Mental State Examination (MMSE) and Clinical Dementia Rating (CDR) for cognitive function assessment at Timepoint 1 and Timepoint 2. We obtained 70 participants (16 men, mean age 72.69 ± 3.18 years; 54 women, mean age 72.69 ± 4.60 years, at Timepoint 1) for analysis. Correlation analysis was performed between serum cortisol levels at baseline (Timepoint 1) and brain volume (Timepoint 1, Timepoint 2, and Timepoint 1-Timepoint 2 difference) using voxel-based morphometry method.

RESULTS

There was no significant difference in serum cortisol levels between men (72.32 ± 17.30 ng/ml) and women (76.60 ± 21.12 ng/ml) at baseline. Additionally, no effect of blood collection time on cortisol levels was observed in these participants. Small volume correction analysis at the cluster level by applying multiple comparison corrections (family-wise error; P < 0.05) showed a negative correlation between serum cortisol levels (Timepoint 1) and brain volume (Timepoint 2) within the region containing the left hippocampus.

CONCLUSIONS

Serum cortisol levels may serve as a peripheral biomarker of age-related volume changes involving the hippocampus in older adults aged 65 years and above.

Myristic acid alleviates hippocampal aging correlated with GABAergic signaling

Previous studies have shown that myristic acid (MA), a saturated fatty acid, could promote the proliferation and differentiation of neural stem cells in vitro. However, the effect of MA on hippocampal neurons aging has not been reported in vivo. Here we employed 22-month-old naturally aged C57BL/6 mice to evaluate the effect and mechanism of MA on hippocampal aging. First, we examined a decreased exploration and spatial memory ability in aging mice using the open field test and Morris water maze. Consistently, aging mice showed degenerative hippocampal histomorphology by H&amp;E and Nissl staining. In terms of mechanism, imbalance of GABRB2 and GABRA2 expression in aging mice might be involved in hippocampus aging by mRNA high throughput sequencing (mRNA-seq) and immunohistochemistry (IHC) validation. Then, we revealed that MA alleviated the damage of exploration and spatial memory ability and ameliorated degeneration and aging of hippocampal neurons. Meanwhile, MA downregulated GABRB2 and upregulated GABRA2 expression, indicating MA might alleviate hippocampal aging correlated with GABAergic signaling. In conclusion, our findings revealed MA alleviated hippocampal aging correlated with GABAergic signaling, which might provide insight into the treatment of aging-associated diseases.

Association between salivary oxytocin levels and the amygdala and hippocampal volumes

Salivary oxytocin levels have been widely measured and studied in relation to social behavior because of procedural simplicity and noninvasiveness. Although the relationship between oxytocin levels in the blood and the hippocampus and amygdala is now becoming clear with reliable blood oxytocin studies, few studies have examined the relationship between salivary oxytocin and the brain function and structure. This study aimed to investigate whether the salivary oxytocin level is associated with the volume of the amygdala and hippocampus in 178 adults (92 women and 86 men) in their third to seventh decade of life. We performed volumetric analysis of the amygdala and hippocampus using FreeSurfer and measured salivary oxytocin levels using enzyme-linked immunosorbent assay. The results showed contradictory effects of the salivary oxytocin level on the amygdala volume by sex and no significant effect on the hippocampal volume. Specifically, men showed a positive correlation between the salivary oxytocin level and amygdala volume, whereas women showed a negative correlation between the salivary oxytocin level and amygdala volume. The present study's finding of sex differences in the association between salivary oxytocin and brain structure supports previous findings that there are sex differences in the oxytocin system.

Sex-Differential Associations Between Body Mass Index and the Incidence of Dementia

BACKGROUND

Little is known about the sex differences in the association between body mass index (BMI) and dementia in late life.

OBJECTIVE

Therefore, this retrospective cohort study aimed to analyze associations between BMI and dementia in older women and men separately in general practices in Germany.

METHODS

This study included patients followed in one of 832 general practices in Germany between 2006 and 2019 (index date: first visit date). Study variables included dementia (dependent variable), BMI (independent variable), age, sex, and comorbidities (control variables). Kaplan-Meier curves and adjusted Cox regression analyses were conducted to analyze associations between BMI and the 10-year incidence of dementia in women and men, separately.

RESULTS

There were 296,767 patients included in this study (mean [standard deviation] age 70.2 [5.9] years; 54.3% women). The proportion of underweight, normal weight, overweight, and obesity was 0.9%, 25.5%, 41.5%, and 32.1%, respectively. The 10-year incidence of dementia significantly decreased with increasing BMI, from 11.5% in women with underweight to 9.1% in those with obesity (log-rank p <  0.001). Respective figures in men were 12.0% and 8.2% (log-rank p <  0.001). In women, only overweight (versus normal weight) was significantly associated with dementia (HR = 0.93, 95% CI = 0.88-0.97). In contrast, in men, the only BMI category significantly associated with the incidence of dementia was underweight (HR = 1.58, 95% CI = 1.11-2.25).

CONCLUSION

In this study conducted in Germany, overweight was negatively associated with dementia in women, whereas there was a positive underweight-dementia relationship in men. More data are needed to confirm or refute these findings in other settings.

Prediction of Chronological Age in Healthy Elderly Subjects with Machine Learning from MRI Brain Segmentation and Cortical Parcellation

Normal aging is associated with changes in volumetric indices of brain atrophy. A quantitative understanding of age-related brain changes can shed light on successful aging. To investigate the effect of age on global and regional brain volumes and cortical thickness, 3514 magnetic resonance imaging scans were analyzed using automated brain segmentation and parcellation methods in elderly healthy individuals (69–88 years of age). The machine learning algorithm extreme gradient boosting (XGBoost) achieved a mean absolute error of 2 years in predicting the age of new subjects. Feature importance analysis showed that the brain-to-intracranial-volume ratio is the most important feature in predicting age, followed by the hippocampi volumes. The cortical thickness in temporal and parietal lobes showed a superior predictive value than frontal and occipital lobes. Insights from this approach that integrate model prediction and interpretation may help to shorten the current explanatory gap between chronological age and biological brain age.

Oxytocin and vasopressin in the hippocampus

Oxytocin (OXT) and vasopressin (AVP) are related neuropeptides that exert a wide range of effects on general health, homeostasis, development, reproduction, adaptability, cognition, social and nonsocial behaviors. The two peptides are mainly of hypothalamic origin and execute their peripheral and central physiological roles via OXT and AVP receptors, which are members of the G protein-coupled receptor family. These receptors, largely distributed in the body, are abundantly expressed in the hippocampus, a brain region particularly vulnerable to stress exposure and various lesions. OXT and AVP have important roles in the hippocampus, by modulating important processes like neuronal excitability, network oscillatory activity, synaptic plasticity, and social recognition memory. This chapter includes an overview regarding OXT and AVP structure, synthesis, receptor distribution, and functions, focusing on their relationship with the hippocampus and mechanisms by which they influence hippocampal activity. Brief information regarding hippocampal structure and susceptibility to lesions is also provided. The roles of OXT and AVP in neurodevelopment and adult central nervous system function and disorders are highlighted, discussing their potential use as targeted therapeutic tools in neuropsychiatric diseases.

Neural Functions of Hypothalamic Oxytocin and its Regulation

Oxytocin (OT), a nonapeptide, has a variety of functions. Despite extensive studies on OT over past decades, our understanding of its neural functions and their regulation remains incomplete. OT is mainly produced in OT neurons in the supraoptic nucleus (SON), paraventricular nucleus (PVN) and accessory nuclei between the SON and PVN. OT exerts neuromodulatory effects in the brain and spinal cord. While magnocellular OT neurons in the SON and PVN mainly innervate the pituitary and forebrain regions, and parvocellular OT neurons in the PVN innervate brainstem and spinal cord, the two sets of OT neurons have close interactions histologically and functionally. OT expression occurs at early life to promote mental and physical development, while its subsequent decrease in expression in later life stage accompanies aging and diseases. Adaptive changes in this OT system, however, take place under different conditions and upon the maturation of OT release machinery. OT can modulate social recognition and behaviors, learning and memory, emotion, reward, and other higher brain functions. OT also regulates eating and drinking, sleep and wakefulness, nociception and analgesia, sexual behavior, parturition, lactation and other instinctive behaviors. OT regulates the autonomic nervous system, and somatic and specialized senses. Notably, OT can have different modulatory effects on the same function under different conditions. Such divergence may derive from different neural connections, OT receptor gene dimorphism and methylation, and complex interactions with other hormones. In this review, brain functions of OT and their underlying neural mechanisms as well as the perspectives of their clinical usage are presented.

The Effects of Oxytocin on Appetite Regulation, Food Intake and Metabolism in Humans

The hypothalamic peptide oxytocin and its receptor are involved in a range of physiological processes, including parturition, lactation, cell growth, wound healing, and social behavior. More recently, increasing evidence has established the effects of oxytocin on food intake, energy expenditure, and peripheral metabolism. In this review, we provide a comprehensive description of the central oxytocinergic system in which oxytocin acts to shape eating behavior and metabolism. Next, we discuss the peripheral beneficial effects oxytocin exerts on key metabolic organs, including suppression of visceral adipose tissue inflammation, skeletal muscle regeneration, and bone tissue mineralization. A brief summary of oxytocin actions learned from animal models is presented, showing that weight loss induced by chronic oxytocin treatment is related not only to its anorexigenic effects, but also to the resulting increase in energy expenditure and lipolysis. Following an in-depth discussion on the technical challenges related to endogenous oxytocin measurements in humans, we synthesize data related to the association between endogenous oxytocin levels, weight status, metabolic syndrome, and bone health. We then review clinical trials showing that in humans, acute oxytocin administration reduces food intake, attenuates fMRI activation of food motivation brain areas, and increases activation of self-control brain regions. Further strengthening the role of oxytocin in appetite regulation, we review conditions of hypothalamic insult and certain genetic pathologies associated with oxytocin depletion that present with hyperphagia, extreme weight gain, and poor metabolic profile. Intranasal oxytocin is currently being evaluated in human clinical trials to learn whether oxytocin-based therapeutics can be used to treat obesity and its associated sequela. At the end of this review, we address the fundamental challenges that remain in translating this line of research to clinical care.

No association of both serum pro-brain-derived neurotrophic factor (proBDNF) and BDNF concentrations with depressive state in community-dwelling elderly people

BACKGROUND

Brain-derived neurotrophic factor (BDNF) is involved in emotional and cognitive function. Low-BDNF levels occur in patients with depression, while proBDNF, a precursor of BDNF with the opposite physiological function, increases in major depression. However, it is unclear whether BDNF and proBDNF are associated with depression in the elderly. The present study aimed to investigate whether serum proBDNF and BDNF are associated with depressive state in community-dwelling elderly people.

METHODS

This was a cross-sectional study conducted in Kurogawa-cho Imari, Saga Prefecture, Japan, in people aged ≥65 years. Depressive state was assessed using the Geriatric Depression Scale-Short Form (Japanese version) (GDS). Of the 274 patients who undertook the GDS, those with a medical history affecting cognitive function were excluded, as were those with Mini-Mental State Examination score ≥ 24 or a Clinical Dementia Rating < 0.5. Further, we used delayed recall of 'logical memory A' from the Wechsler Memory Scale-Revised (LMII-DR) for memory assessment.

RESULTS

The final sample consisted of 155 individuals (mean age 75.4 ± 6.8 years; 55 men, mean age 74.8 ± 5.9 years; 100 women, mean age 76.3 ± 7.1 years). In the GDS, 139 participants showed a normal score (0-4) and 16 showed depressive tendencies or depression (score: ≥ 5). After examining confounders of the GDS, logistic regression using categorical covariates showed a negative significant difference between depressive state and serum BDNF in the low-BDNF group only, with a positive correlation in the trend test. None of the analyses showed any association between GDS and proBDNF levels.

CONCLUSION

ProBDNF and BDNF levels seemed not to be associated with depressive state in community-dwelling elderly people.

Association Between sTREM2, an Immune Biomarker of Microglial Activation, and Aging-Related Brain Volume Changes in Community-Dwelling Older Adults: A 7-Year Follow-Up Study

Background

This study aimed to investigate the association between serum levels of soluble triggering receptor expressed on myeloid cells 2 (sTREM2), a soluble form of an innate immune receptor expressed on the microglia, and brain volume in older adults.

Methods

The survey was conducted twice in Kurokawa-cho, Imari, Saga Prefecture, Japan, among people aged 65 years and older. We collected data from 596 residents. Serum sTREM2 level measurements, brain MRI, Mini-Mental State Examination (MMSE), and clinical dementia rating (CDR) were performed at Time 1 (2009–2011). Follow-up brain MRI, MMSE, and CDR were performed at Time 2 (2016–2017). The interval between Time 1 and Time 2 was approximately 7 years. Sixty-nine participants (16 men, mean age 72.69 ± 3.18 years; 53 women, mean age 72.68 ± 4.64 years) completed this study. We analyzed the correlation between serum sTREM2 levels (Time 1) and brain volume (Time 1, Time 2, and Time 1–Time 2 difference) using voxel-based morphometry implemented with Statistical Parametric Mapping.

Results

Participants in this study had lower MMSE and higher CDR scores 7 years after the baseline evaluation. However, analyses at the cluster level by applying multiple comparison corrections (family wise error; P < 0.05) showed no correlation between serum sTREM2 levels and volume of different brain regions, either cross-sectional or longitudinal.

Conclusion

Serum sTREM2 level could not serve as an immune biomarker of aging-related volume changes in brain regions closely related to cognitive function in older adults aged 65 years and above.