The age-by-disease interaction hypothesis of late-life depression

MIAMI-AD (Methylation in Aging and Methylation in AD): an integrative knowledgebase that facilitates explorations of DNA methylation across sex, aging, and Alzheimer's disease

Alzheimer's disease (AD) is a common neurodegenerative disorder with a significant impact on aging populations. DNA methylation (DNAm) alterations have been implicated in both the aging processes and the development of AD. Given that AD affects more women than men, it is also important to explore DNAm changes that occur specifically in each sex. We created MIAMI-AD, a comprehensive knowledgebase containing manually curated summary statistics from 98 published tables in 38 studies, all of which included at least 100 participants. MIAMI-AD enables easy browsing, querying, and downloading DNAm associations at multiple levels-at individual CpG, gene, genomic regions, or genome-wide, in one or multiple studies. Moreover, it also offers tools to perform integrative analyses, such as comparing DNAm associations across different phenotypes or tissues, as well as interactive visualizations. Using several use case examples, we demonstrated that MIAMI-AD facilitates our understanding of age-associated CpGs in AD and the sex-specific roles of DNAm in AD. This open-access resource is freely available to the research community, and all the underlying data can be downloaded. MIAMI-AD facilitates integrative explorations to better understand the interplay between DNAm across aging, sex, and AD. Database URL: https://miami-ad.org/.

MIAMI-AD (Methylation in Aging and Methylation in AD): an integrative knowledgebase that facilitates explorations of DNA methylation across sex, aging, and Alzheimer's disease

Alzheimer's disease (AD) is a common neurodegenerative disorder with a significant impact on aging populations. DNA methylation (DNAm) alterations have been implicated in both the aging processes and the development of AD. Given that AD affects more women than men, it is also important to explore DNAm changes that occur specifically in each sex. We created MIAMI-AD, a comprehensive knowledge base containing manually curated summary statistics from 97 published tables in 37 studies, all of which included at least 100 participants. MIAMI-AD enables easy browsing, querying, and downloading DNAm associations at multiple levels - at individual CpG, gene, genomic regions, or genome-wide, in one or multiple studies. Moreover, it also offers tools to perform integrative analyses, such as comparing DNAm associations across different phenotypes or tissues, as well as interactive visualizations. Using several use case examples, we demonstrated that MIAMI-AD facilitates our understanding of age-associated CpGs in AD and the sex-specific roles of DNAm in AD. This open-access resource is freely available to the research community, and all the underlying data can be downloaded. MIAMI-AD (https://miami-ad.org/) facilitates integrative explorations to better understand the interplay between DNAm across aging, sex, and AD.

Cannabidiol Modulates Emotional Function and Brain-Derived Neurotrophic Factor Expression in Middle-Aged Female Rats Exposed to Social Isolation

Aging is associated with changes in cognitive and emotional function. Cannabidiol (CBD) has been reported to attenuate stress and anxiety in human and animal studies. In this study, we aimed to assess the therapeutic potential of CBD among middle-aged female rats exposed to social isolation (SI) and the potential involvement of brain-derived neurotrophic factor (BDNF) in these effects. Thirteen-month-old female rats were group-housed (GH) or exposed to social isolation (SI) and treated with vehicle or CBD (10 mg/kg). CBD restored the SI-induced immobility in the forced swim test and the SI-induced decrease in the expression of BDNF protein levels in the nucleus accumbens (NAc). CBD also increased the time that rats spent in the center in an open field, improved spatial training, and increased BDNF expression in the medial prefrontal cortex (mPFC) and basolateral amygdala (BLA). BDNF expression was found to be correlated with an antidepressant (in the NAc) and an anxiolytic (in the mPFC, BLA, NAc) phenotype, and with learning improvement in the PFC. Together, our results suggest that CBD may serve as a beneficial agent for wellbeing in old age and may help with age-related cognitive decline.

Exploratory genome-wide analyses of cortical inhibition, facilitation, and plasticity in late-life depression

Late-life depression (LLD) is a heterogenous mood disorder influenced by genetic factors. Cortical physiological processes such as cortical inhibition, facilitation, and plasticity may be markers of illness that are more strongly associated with genetic factors than the clinical phenotype. Thus, exploring the relationship between genetic factors and these physiological processes may help to characterize the biological mechanisms underlying LLD and improve diagnosis and treatment selection. Transcranial magnetic stimulation (TMS) combined with electromyography was used to measure short interval intracortical inhibition (SICI), cortical silent period (CSP), intracortical facilitation (ICF), and paired associative stimulation (PAS) in 79 participants with LLD. We used exploratory genome-wide association and gene-based analyses to assess for genetic correlations of these TMS measures. MARK4 (which encodes microtubule affinity-regulating kinase 4) and PPP1R37 (which encodes protein phosphatase 1 regulatory subunit 37) showed genome-wide significant association with SICI. EGFLAM (which encodes EGF-like fibronectin type III and laminin G domain) showed genome-wide significant association with CSP. No genes met genome-wide significant association with ICF or PAS. We observed genetic influences on cortical inhibition in older adults with LLD. Replication with larger sample sizes, exploration of clinical phenotype subgroups, and functional analysis of relevant genotypes is warranted to better characterize genetic influences on cortical physiology in LLD. This work is needed to determine whether cortical inhibition may serve as a biomarker to improve diagnostic precision and guide treatment selection in LLD.

Cross-tissue analysis of blood and brain epigenome-wide association studies in Alzheimer's disease

To better understand DNA methylation in Alzheimer's disease (AD) from both mechanistic and biomarker perspectives, we performed an epigenome-wide meta-analysis of blood DNA methylation in two large independent blood-based studies in AD, the ADNI and AIBL studies, and identified 5 CpGs, mapped to the SPIDR, CDH6 genes, and intergenic regions, that are significantly associated with AD diagnosis. A cross-tissue analysis that combined these blood DNA methylation datasets with four brain methylation datasets prioritized 97 CpGs and 10 genomic regions that are significantly associated with both AD neuropathology and AD diagnosis. An out-of-sample validation using the AddNeuroMed dataset showed the best performing logistic regression model includes age, sex, immune cell type proportions, and methylation risk score based on prioritized CpGs in cross-tissue analysis (AUC = 0.696, 95% CI: 0.616 - 0.770, P-value = 2.78 × 10^-5). Our study offers new insights into epigenetics in AD and provides a valuable resource for future AD biomarker discovery.

Dose-Dependent Antidepressant-Like Effects of Cannabidiol in Aged Rats

Aging predisposes to late-life depression and since antidepressants are known to change their efficacy with age, novel treatment options are needed for our increased aged population. In this context, the goal of the present study was to evaluate the potential antidepressant-like effect of cannabidiol in aged rats. For this purpose, 19–21-month-old Sprague–Dawley rats were treated for 7 days with cannabidiol (dose range: 3–30 mg/kg) and scored under the stress of the forced-swim test. Hippocampal cannabinoid receptors and cell proliferation were evaluated as potential molecular markers underlying cannabidiol’s actions. The main results of the present study demonstrated that cannabidiol exerted a dose-dependent antidepressant-like effect in aged rats (U-shaped, effective at the intermediate dose of 10 mg/kg as compared to the other doses tested), without affecting body weight. None of the molecular markers analyzed in the hippocampus were altered by cannabidiol’s treatment. Overall, this study demonstrated a dose-dependent antidepressant-like response for cannabidiol at this age-window (aged rats up to 21 months old) and in line with other studies suggesting a beneficial role for this drug in age-related behavioral deficits.

Transcranial Magnetic Stimulation Indices of Cortical Excitability Enhance the Prediction of Response to Pharmacotherapy in Late-Life Depression

BACKGROUND

Older adults with late-life depression (LLD) often experience incomplete or lack of response to first-line pharmacotherapy. The treatment of LLD could be improved using objective biological measures to predict response. Transcranial magnetic stimulation (TMS) can be used to measure cortical excitability, inhibition, and plasticity, which have been implicated in LLD pathophysiology and associated with brain stimulation treatment outcomes in younger adults with depression. TMS measures have not yet been investigated as predictors of treatment outcomes in LLD or pharmacotherapy outcomes in adults of any age with depression.

METHODS

We assessed whether pretreatment single-pulse and paired-pulse TMS measures, combined with clinical and demographic measures, predict venlafaxine treatment response in 76 outpatients with LLD. We compared the predictive performance of machine learning models including or excluding TMS predictors.

RESULTS

Two single-pulse TMS measures predicted venlafaxine response: cortical excitability (neuronal membrane excitability) and the variability of cortical excitability (dynamic fluctuations in excitability levels). In cross-validation, models using a combination of these TMS predictors, clinical markers of treatment resistance, and age classified patients with 73% ± 11% balanced accuracy (average correct classification rate of responders and nonresponders; permutation testing, p < .005); these models significantly outperformed (corrected t test, p = .025) models using clinical and demographic predictors alone (60% ± 10% balanced accuracy).

CONCLUSIONS

These preliminary findings suggest that single-pulse TMS measures of cortical excitability may be useful predictors of response to pharmacotherapy in LLD. Future studies are needed to confirm these findings and determine whether combining TMS predictors with other biomarkers further improves the accuracy of predicting LLD treatment outcome.

Cortical inhibition, facilitation and plasticity in late-life depression: effects of venlafaxine pharmacotherapy

BACKGROUND

Late-life depression is often associated with non-response or relapse following conventional antidepressant treatment. The pathophysiology of late-life depression likely involves a complex interplay between aging and depression, and may include abnormalities in cortical inhibition and plasticity. However, the extent to which these cortical processes are modifiable by antidepressant pharmacotherapy is unknown.

METHODS

Sixty-eight patients with late-life depression received 12 weeks of treatment with open-label venlafaxine, a serotonin-norepinephrine reuptake inhibitor (≤ 300 mg/d). We combined transcranial magnetic stimulation of the left motor cortex with electromyography recordings from the right hand to measure cortical inhibition using contralateral cortical silent period and paired-pulse short-interval intracortical inhibition paradigms; cortical facilitation using a paired-pulse intracortical facilitation paradigm; and short-term cortical plasticity using a paired associative stimulation paradigm. All measures were collected at baseline, 1 week into treatment (n = 23) and after approximately 12 weeks of treatment.

RESULTS

Venlafaxine did not significantly alter cortical inhibition, facilitation or plasticity after 1 or 12 weeks of treatment. Improvements in depressive symptoms during treatment were not associated with changes in cortical physiology.

LIMITATIONS

The results presented here are specific to the motor cortex. Future work should investigate whether these findings extend to cortical areas more closely associated with depression, such as the dorsolateral prefrontal cortex.

CONCLUSION

These findings suggest that antidepressant treatment with venlafaxine does not exert meaningful changes in motor cortical inhibition or plasticity in late-life depression. The absence of changes in motor cortical physiology, alongside improvements in depressive symptoms, suggests that age-related changes may play a role in previously identified abnormalities in motor cortical processes in latelife depression, and that venlafaxine treatment does not target these abnormalities.

Enhancing Health Care in the Veteran Community Through Synergistic Research Funding

The veteran population faces myriad health burdens, particularly regarding mental health. As veterans age, combined genetic, environmental, and biochemical factors with natural biological processes may increase their susceptibility to mental health disorders as well as neuropsychiatric and dementia-related disorders that present as persistent cognitive impairment. Multi-organizational, multidisciplinary research partnerships help explore relevant evidence-based methodologies and create a two-way continuum between basic science and clinical application to address veterans', often complex, health care needs. The Congressionally Directed Medical Research Programs (CDMRP), a global funding organization located within the U.S. Army Medical Research and Development Command (USAMRDC), fosters novel approaches to biomedical research in response to the expressed needs of stakeholders and, as directed by Congress, many CDMRP programs focus on topics that are relevant to the health care of veterans. The CDMRP's foundation as a research management organization includes a two-tier review process and fully integrates consumer advocates. The CDMRP complements the U.S. Department of Veterans Affairs (VA) research through collaborative partnerships and synergistic award mechanisms tailored to areas of greatest need. Continued partnerships between the VA and CDMRP can facilitate translation of basic research to clinical application and enhance health care in the veteran community. This perspective highlights the need for research to address mental health issues affecting the veteran community, describes how the CDMRP integrates veterans into its processes, and discusses how the CDMRP's processes and collaborations with the VA have the capacity to improve mental health care for veterans.

Mental health and related influencing factors among rural elderly in 14 poverty state counties of Chongqing, Southwest China: a cross-sectional study

BACKGROUND

China has the largest elderly population in the world; little attention has been paid to the mental health of elderly in areas of extreme poverty. This is the first study to investigate the mental health of the rural elderly in poverty state counties in Chongqing and was part of the Chongqing 2018 health literacy promotion project.

METHODS

In 2019, a cross-sectional study was conducted to investigate the mental health status of the rural elderly in fourteen poverty state counties of Chongqing, in which a total of 1400 elderly aged ≥ 65 years were interviewed, where mental health status was measured by the ten-item Kessler10 (K10) scale. Ordered multivariate logistic regression was performed to evaluate the influencing factors related to mental health of the elderly in these areas.

RESULTS

The average score of K10 in 14 poverty state counties was 17.40 ± 6.31, 47.6% was labeled as good, 30.2% was moderate, 17.0% was poor, and lastly 5.1% was bad, and the mental health status of the elderly in the northeastern wing of Chongqing was better than the one in the southeastern wing of Chongqing. A worse self-rated health was the risk factor for mental health both in the northeastern and southeastern wings of Chongqing (all P < 0.001). Lower education level (OR (95% CI) = 1.45 (1.12-1.87), P = 0.004) was a risk factor in the northeastern wing, whereas older age (OR (95% CI) = 1.33 (1.13-1.56), P = 0.001) was a risk factors in the southeastern wing.

CONCLUSIONS

The results showed that mental health of the elderly in poverty state counties was poor, especially in the southeastern wing of Chongqing. Particular attention needs to be paid to the males who were less educated, older, and single; female with lower annual per capital income; and especially the elderly with poor self-rated health.

Canalization and Robustness in Human Genetics and Disease

Canalization refers to the evolution of populations such that the number of individuals who deviate from the optimum trait, or experience disease, is minimized. In the presence of rapid cultural, environmental, or genetic change, the reverse process of decanalization may contribute to observed increases in disease prevalence. This review starts by defining relevant concepts, drawing distinctions between the canalization of populations and robustness of individuals. It then considers evidence pertaining to three continuous traits and six domains of disease. In each case, existing genetic evidence for genotype-by-environment interactions is insufficient to support a strong inference of decanalization, but we argue that the advent of genome-wide polygenic risk assessment now makes an empirical evaluation of the role of canalization in preventing disease possible. Finally, the contributions of both rare and common variants to congenital abnormality and adult onset disease are considered in light of a new kerplunk model of genetic effects.

Molecular and Cellular Evidence for Age by Disease Interactions: Updates and Path Forward

Characterization of age-associated gene expression changes shows that the brain engages a specific set of genes and biologic pathways along a continuous life-long trajectory and that these genes and pathways overlap with those associated with brain-related disorders. Based on this correlative observation, we have suggested a model of age-by-disease interaction by which brain ageing promotes biologic changes associated with diseases and where deviations from expected age-related trajectories, due to biologic and environmental factors, contribute to defining disease risk or resiliency. In this review, we first evaluate various biomarkers that can be used to study age-by-disease interactions and then focus on transcriptome analysis (i.e., the set of all expressed genes) as a useful tool to explore this interaction. Using the specific example of brain-derived neurotrophic factor and brain-derived neurotrophic factor-associated genes, we then describe molecular events and mechanisms potentially contributing to age-by-disease interactions. Finally, we suggest that long-term biologic adaptations within distinct cellular components of cortical microcircuits, as determined by transcriptome analysis, may integrate and mediate the effects of ageing and diseases. Moving forward, we suggest that analysis of transcriptome similarities between ageing and small molecule-induced system perturbations may lead to novel therapeutics discovery.

The Relative Contributions of Cell-Dependent Cortical Microcircuit Aging to Cognition and Anxiety

BACKGROUND

Aging is accompanied by altered thinking (cognition) and feeling (mood), functions that depend on information processing by brain cortical cell microcircuits. We hypothesized that age-associated long-term functional and biological changes are mediated by gene transcriptomic changes within neuronal cell types forming cortical microcircuits, namely excitatory pyramidal cells (PYCs) and inhibitory gamma-aminobutyric acidergic neurons expressing vasoactive intestinal peptide (Vip), somatostatin (Sst), and parvalbumin (Pvalb).

METHODS

To test this hypothesis, we assessed locomotor, anxiety-like, and cognitive behavioral changes between young (2 months of age, n = 9) and old (22 months of age, n = 12) male C57BL/6 mice, and performed frontal cortex cell type-specific molecular profiling, using laser capture microscopy and RNA sequencing. Results were analyzed by neuroinformatics and validated by fluorescent in situ hybridization.

RESULTS

Old mice displayed increased anxiety and reduced working memory. The four cell types displayed distinct age-related transcriptomes and biological pathway profiles, affecting metabolic and cell signaling pathways, and selective markers of neuronal vulnerability (Ryr3), resilience (Oxr1), and mitochondrial dynamics (Opa1), suggesting high age-related vulnerability of PYCs, and variable degree of adaptation in gamma-aminobutyric acidergic neurons. Correlations between gene expression and behaviors suggest that changes in cognition and anxiety associated with age are partly mediated by normal age-related cell changes, and that additional age-independent decreases in synaptic and signaling pathways, notably in PYCs and somatostatin neurons, further contribute to behavioral changes.

CONCLUSIONS

Our study demonstrates cell-dependent differential vulnerability and coordinated cell-specific cortical microcircuit molecular changes with age. Collectively, the results suggest intrinsic molecular links among aging, cognition, and mood-related behaviors, with somatostatin neurons contributing evenly to both behavioral conditions.

DNA methylation in the human frontal cortex reveals a putative mechanism for age-by-disease interactions

A consistent gene set undergoes age-associated expression changes in the human cerebral cortex, and our Age-by-Disease Model posits that these changes contribute to psychiatric diseases by "pushing" the expression of disease-associated genes in disease-promoting directions. DNA methylation (DNAm) is an attractive candidate mechanism for age-associated gene expression changes. We used the Illumina HumanMethylation450 array to characterize genome-wide DNAm in the postmortem orbital frontal cortex from 20 younger (<42 years) and 19 older (>60 years) subjects. DNAm data were integrated with existing normal brain aging expression data and sets of psychiatric disease risk genes to test the hypothesis that age-associated DNAm changes contribute to age-associated gene expression changes and, by extension, susceptibility to psychiatric diseases. We found that age-associated differentially methylated regions (aDMRs) are common, robust, bidirectional, concentrated in CpG island shelves and sea, depleted in CpG islands, and enriched among genes undergoing age-associated expression changes (OR = 2.30, p = 1.69 × 10^-27). We found the aDMRs are enriched among genetic association-based risk genes for schizophrenia, Alzheimer's disease (AD), and major depressive disorder (MDD) (OR = 2.51, p = 0.00015; OR = 2.38, p = 0.036; and OR = 3.08, p = 0.018, respectively) as well as expression-based MDD-associated genes (OR = 1.48, p = 0.00012). Similar patterns of enrichment were found for aDMRs that correlate with local gene expression. These results were replicated in a large publically-available dataset, and confirmed by meta-analysis of the two datasets. Our findings suggest DNAm is a molecular mechanism for age-associated gene expression changes and support a role for DNAm in age-by-disease interactions through preferential targeting of disease-associated genes.

The Molecular Intersection Between Senescence and Major Depression in the Elderly

Major depressive disorder in the elderly-or late-life depression (LLD)-is one of the most common mental illnesses in the aging population. LLD has several negative effects on health and well-being. Individuals with LLD have an elevated risk of chronic and persistent depressive symptoms as well as high rates of treatment resistance. They also have a higher risk of developing cognitive impairment with progression to dementia and higher rates of medical comorbidity, frailty, and mortality. The mechanisms linking LLD to these adverse health outcomes are not well understood. In this article, we review the evidence that individuals with LLD present with, i.e., enhanced molecular and cellular senescent changes, focusing on the senescence-associated secretory phenotype (SASP). We then propose a mechanistic model linking SASP to the greater risk of negative health outcomes in this population. We finally provide evidence that SASP-and cellular senescence in general-can be a therapeutic target for mitigating the risk of these negative outcomes in LLD.

Reduced GABAergic cortical inhibition in aging and depression

The neurobiology underlying depression in older adults is less extensively evaluated than in younger adults, despite the putative influence of aging on depression neuropathology. Studies using transcranial magnetic stimulation (TMS), a neurophysiological tool capable of probing inhibitory and excitatory cortical neurotransmission, have identified dysfunctional GABAergic inhibitory activity in younger adults with depression. However, GABAergic and glutamatergic cortical neurotransmission have not yet been studied in late-life depression (LLD). Here, we used single- and paired-pulse TMS to measure cortical inhibition and excitation in 92 LLD patients and 41 age-matched healthy controls. To differentiate the influence of age and depression, we also compared these TMS indices to those of 30 younger depressed adults and 30 age- and sex-matched younger healthy adults. LLD patients, older healthy adults, and younger depressed adults demonstrated significantly lower GABA_A receptor-mediated cortical inhibition than younger healthy controls. By contrast, no significant differences in cortical inhibition were observed between older adults with and without depression. No significant differences in GABA_B receptor-mediated inhibition or cortical excitation were found between the groups. Altogether, these findings suggest that reduced cortical inhibition may be associated with both advancing age and depression, which (i) supports the model of depression as a disease of accelerated aging, and (ii) prompts future investigation into diminished GABAergic neurotransmission in late-life as a biological predisposing factor to the development of depression. Given that cortical neurophysiology was similar in depressed and healthy older adults, future prospective studies need to establish the relative influence of age and depression on cortical inhibition deficits.

Assessment of neuroplasticity in late-life depression with transcranial magnetic stimulation

BACKGROUND

Studies using Transcranial Magnetic Stimulation (TMS), a non-invasive method of brain stimulation, have implicated impaired neuroplasticity in the pathophysiology of depression in younger adults. The role of neuroplasticity in late-life depression (LLD) has not yet been explored using TMS.

OBJECTIVE

This study aimed at evaluating motor cortical neuroplasticity using paired associative stimulation (PAS). Single-pulse TMS was used to induce motor-evoked potentials (MEP) in the contralateral hand muscle before and after PAS. The potentiation of MEP amplitudes after PAS was used as an indirect index of associative plasticity and long-term potentiation (LTP) (i.e. PAS-LTP).

RESULTS

48 older adults with depression and 34 age-matched healthy controls (HC) were compared. PAS- LTP was successfully induced in 68.8% of older adults with depression and 47.1% of HC. At the group level, older adults with depression failed to show statistically significant induction of neuroplasticity, which was observed in HC. However, no significant differences were observed between the two groups for PAS-LTP.

CONCLUSION

Our results suggest that associative plasticity does not differ substantially between older adults with depression and age-matched HC. Continued research is needed to more comprehensively understand the role of neuroplasticity in the pathophysiology of LLD.

Longitudinal relationships among depressive symptoms, cortisol, and brain atrophy in the neocortex and the hippocampus

OBJECTIVE

Depression is associated with accelerated aging and age-related diseases. However, mechanisms underlying this relationship remain unclear. The aim of this study was to longitudinally assess the link between depressive symptoms, brain atrophy, and cortisol levels.

METHOD

Participants from the Betula prospective cohort study (mean age = 59 years, SD = 13.4 years) underwent clinical, neuropsychological and brain 3T MRI assessments at baseline and a 4-year follow-up. Cortisol levels were measured at baseline in four saliva samples. Cortical and hippocampal atrophy rates were estimated and compared between participants with and without depressive symptoms (n = 81) and correlated with cortisol levels (n = 49).

RESULTS

Atrophy in the left superior frontal gyrus and right lingual gyrus developed in parallel with depressive symptoms, and in the left temporal pole, superior temporal cortex, and supramarginal cortex after the onset of depressive symptom. Depression-related atrophy was significantly associated with elevated cortisol levels. Elevated cortisol levels were also associated with widespread prefrontal, parietal, lateral, and medial temporal atrophy.

CONCLUSION

Depressive symptoms and elevated cortisol levels are associated with atrophy of the prefrontal and limbic areas of the brain.

Differential effects of chronic stress in young-adult and old female mice: cognitive-behavioral manifestations and neurobiological correlates

Stress-related psychopathology is highly prevalent among elderly individuals and is associated with detrimental effects on mood, appetite and cognition. Conversely, under certain circumstances repeated mild-to-moderate stressors have been shown to enhance cognitive performance in rodents and exert stress-inoculating effects in humans. As most stress-related favorable outcomes have been reported in adolescence and young-adulthood, this apparent disparity could result from fundamental differences in how aging organisms respond to stress. Furthermore, given prominent age-related alterations in sex hormones, the effect of chronic stress in aging females remains a highly relevant yet little studied issue. In the present study, female C57BL/6 mice aged 3 (young-adult) and 20-23 (old) months were subjected to 8 weeks of chronic unpredictable stress (CUS). Behavioral outcomes were measured during the last 3 weeks of the CUS protocol, followed by brain dissection for histological and molecular end points. We found that in young-adult female mice, CUS resulted in decreased anxiety-like behavior and enhanced cognitive performance, whereas in old female mice it led to weight loss, dysregulated locomotion and memory impairment. These phenotypes were paralleled by differential changes in the expression of hypothalamic insulin and melanocortin-4 receptors and were consistent with an age-dependent reduction in the dynamic range of stress-related changes in the hippocampal transcriptome. Supported by an integrated microRNA (miRNA)-mRNA expression analysis, the present study proposes that, when confronted with ongoing stress, neuroprotective mechanisms involving the upregulation of neurogenesis, Wnt signaling and miR-375 can be harnessed more effectively during young-adulthood. Conversely, we suggest that aging alters the pattern of immune activation elicited by stress. Ultimately, interventions that modulate these processes could reduce the burden of stress-related psychopathology in late life.

Besides Depression, Number of Physiological Diseases is More Important than Physical Function on Mental Health of Elderly Adults in Taiwan

This study contrasted the relative importance between the number of physiological diseases and activities of daily living (ADLs) to the mental health of elderly adults after controlling for mini-mental state exam (MMSE) scores and depression. Participants were 1342 elderly people with a mean age of 73.22 years and living in three communities in southern Taiwan. Age, gender, years of education duration, marital status, and MMSE and hamilton depression rating scale (HAMD) scores were control variables. The ability of the ADLs scale scores and number of physiological diseases to predict mental health, as measured by the 12-item Chinese health questionnaire, was compared using hierarchical regression analyses. The final hierarchical model indicated that only HAMD and the number of physiological diseases scores were significant and that the former was much more predictive than the latter. The results imply that the number of physiological diseases is more predictive of mental health than ADLs scores and that depression is a dangerous risk factor for elderly people.

Differentially Severe Cognitive Effects of Compromised Cerebral Blood Flow in Aged Mice: Association with Myelin Degradation and Microglia Activation

Bilateral common carotid artery stenosis (BCAS) models the effects of compromised cerebral blood flow on brain structure and function in mice. We compared the effects of BCAS in aged (21 month) and young adult (3 month) female mice, anticipating a differentially more severe effect in the older mice. Four weeks after surgery there was a significant age by time by treatment interaction on the radial-arm water maze (RAWM; p = 0.014): on the first day of the test, latencies of old mice were longer compared to the latencies of young adult mice, independent of BCAS. However, on the second day of the test, latencies of old BCAS mice were significantly longer than old control mice (p = 0.049), while latencies of old controls were similar to those of the young adult mice, indicating more severe impairment of hippocampal dependent learning and working memory by BCAS in the older mice. Fluorescence staining of myelin basic protein (MBP) showed that old age and BCAS both induced a significant decrease in fluorescence intensity. Evaluation of the number oligodendrocyte precursor cells demonstrated augmented myelin replacement in old BCAS mice (p < 0.05) compared with young adult BCAS and old control mice. While microglia morphology was assessed as normal in young adult control and young adult BCAS mice, microglia of old BCAS mice exhibited striking activation in the area of degraded myelin compared to young adult BCAS (p < 0.01) and old control mice (p < 0.05). These findings show a differentially more severe effect of cerebral hypoperfusion on cognitive function, myelin integrity and inflammatory processes in aged mice. Hypoperfusion may exacerbate degradation initiated by aging, which may induce more severe neuronal and cognitive phenotypes.

MRI-Based Classification Models in Prediction of Mild Cognitive Impairment and Dementia in Late-Life Depression

Objective: Late-life depression (LLD) is associated with development of different types of dementia. Identification of LLD patients, who will develop cognitive decline, i.e., the early stage of dementia would help to implement interventions earlier. The purpose of this study was to assess whether structural brain magnetic resonance imaging (MRI) in LLD patients can predict mild cognitive impairment (MCI) or dementia 1 year prior to the diagnosis.

Methods: LLD patients underwent brain MRI at baseline and repeated clinical assessment after 1-year. Structural brain measurements were obtained using Freesurfer software (v. 5.1) from the T1W brain MRI images. MRI-based Random Forest classifier was used to discriminate between LLD who developed MCI or dementia after 1-year follow-up and cognitively stable LLD. Additionally, a previously established Random Forest model trained on 185 patients with Alzheimer’s disease (AD) vs. 225 cognitively normal elderly from the Alzheimer’s disease Neuroimaging Initiative was tested on the LLD data set (ADNI model).

Results: MCI and dementia diagnoses were predicted in LLD patients with 76%/68%/84% accuracy/sensitivity/specificity. Adding the baseline Mini-Mental State Examination (MMSE) scores to the models improved accuracy/sensitivity/specificity to 81%/75%/86%. The best model predicted MCI status alone using MRI and baseline MMSE scores with accuracy/sensitivity/specificity of 89%/85%/90%. The most important region for all the models was right ventral diencephalon, including hypothalamus. Its volume correlated negatively with the number of depressive episodes. ADNI model trained on AD vs. Controls using SV could predict MCI-DEM patients with 67% accuracy.

Conclusion: LDD patients developing MCI and dementia can be discriminated from LLD patients remaining cognitively stable with good accuracy based on baseline structural MRI alone. Baseline MMSE score improves prediction accuracy. Ventral diencephalon, including the hypothalamus might play an important role in preservation of cognitive functions in LLD.

The Role of BDNF in Age-Dependent Changes of Excitatory and Inhibitory Synaptic Markers in the Human Prefrontal Cortex

Reduced brain-derived neurotrophic factor (BDNF) may underlie age-related synaptic loss, in turn contributing to cerebral atrophy, cognitive decline, and increased risk for psychiatric disorders. However, the specific contribution of BDNF to the age-related expression changes in synaptic markers and their temporal trajectories remain uncharacterized. Using microarray data from orbitofrontal cortex of control subjects (n=209; 16-96 years), we identified genes whose expression positively correlates with BDNF (r>0.575; n=200 genes) and analyzed them for enriched biological pathways. qPCR was performed to measure the expression level of transcript variants of BDNF, NTRK2, and selected BDNF-coexpressed genes in younger and older subjects. We confirmed age-related downregulation of BDNF and show 78 of the top 200 BDNF-coexpressed genes are associated with synaptic function. Both excitatory and inhibitory synaptic genes show decreased expression with age and are positively correlated with BDNF and NTRK2 expression and negatively correlated with dominant-negative truncated NTRK2 level. Results were validated at the RNA level in an independent cohort and at the protein level for selected findings. We next tested the causal link between the correlative human findings using mice with conditional blockade of BDNF/NTRK2 signaling. Blockade of NTRK2 activity in adult mice recapitulate the age-like pattern in the expression of markers for inhibitory presynaptic but notably not for excitatory synaptic genes. Together, these findings suggest that age-dependent decrease in BDNF signaling may cause synaptic alterations through an initial and preferential effect on GABA presynaptic genes. These results have implications for neuropsychiatric disorders characterized by accelerated aging molecular profiles, such as major depression.

[Late-onset depression : Pathophysiology, diagnostics and treatment]

Late-onset depression (LOD) is defined as depression manifesting for the first time in later life. Up to now, there has been no exact definition of the lower age limit for LOD. Psychopathological symptoms of LOD do not fundamentally differ from depression in other phases of life; however, cognitive deficits are typically more pronounced. The LOD is associated with an increased risk of developing dementia. Imaging studies show reduction in gray matter volume and white matter lesions caused by vascular diseases. The occurrence of depression with vascular lesions of the brain is also referred to as "vascular depression". The diagnostic procedure includes a detailed medical history and the observation of psychopathological changes, physical examination, laboratory tests, electroencephalograph (EEG), electrocardiograph (ECG) and magnetic resonance imaging (MRI) of the head and neuropsychological tests to measure cognitive deficits. Psychotherapy is an effective treatment option. Selective serotonin reuptake inhibitors are the first-line pharmacological therapy.

The double burden of age and major depressive disorder on the cognitive control network

Poor cognitive control (CC) is common among older individuals with major depressive disorder (OMDD). At the same time, studies of CC in OMDD with fMRI are relatively limited and often have small samples. The present study was conducted to further examine poor CC in OMDD with early onset depression, as well as to investigate the interactive effects of MDD and aging on cognitive control. Twenty OMDD, 17 older never-depressed comparisons (ONDC), 16 younger adults with MDD (YMDD), and 18 younger never-depressed comparisons (YNDC) participated. All participants completed the Go level of the Parametric Go/No-Go Test, which requires sustained attention and inhibitory control while undergoing functional MRI (fMRI). YNDC were faster in reaction times (RTs) to go targets relative to the other 3 groups, and the YMDD group was faster than the OMDD group. fMRI effects of both age and diagnosis were present, with greater activation in MDD, and in aging. Additionally, the interaction of age and MDD was also significant, such that OMDD exhibited greater recruitment of fronto-subcortical regions relative to older comparisons. These results are consistent with prior research reporting that OMDD recruit more fronto-striatal regions in order to perform at the same level as their never-depressed peers, here on a task of sustained attention and inhibitory control. There may be an interaction of cognitive aging and depression to create a double burden on the CC network in OMDD, including possible fronto-striatal compensation during CC that is unique to OMDD, as younger MDD individuals do not show this pattern.

Hypermethylation of BDNF and SST Genes in the Orbital Frontal Cortex of Older Individuals: A Putative Mechanism for Declining Gene Expression with Age

Expression of brain-derived neurotrophic factor (BDNF) and somatostatin (SST) mRNAs in the brain decreases progressively and robustly with age, and lower BDNF and SST expression in the brain has been observed in many brain disorders. BDNF is known to regulate SST expression; however, the mechanisms underlying decreased expression of both genes are not understood. DNA methylation (DNAm) is an attractive candidate mechanism. To investigate the contribution of DNAm to the age-related decline in BDNF and SST expression, the Illumina Infinium HumanMethylation450 Beadchip Array was used to quantify DNAm of BDNF (26 CpG loci) and SST (9 CpG loci) in the orbital frontal cortices of postmortem brains from 22 younger (age <42 years) and 22 older individuals (age >60 years) with known age-dependent BDNF and SST expression differences. Relative to the younger individuals, 10 of the 26 CpG loci in BDNF and 8 of the 9 CpG loci in SST were significantly hypermethylated in the older individuals. DNAm in BDNF exons/promoters I, II, and IV negatively correlated with BDNF expression (r=-0.37, p<0.05; r=-0.40, p<0.05; r=-0.24, p=0.07), and DNAm in SST 5' UTR and first exon/intron negatively correlated with SST expression (r=-0.48, p<0.01; r=-0.63, p<0.001), respectively. An expanded set of BDNF- and GABA-related genes exhibited similar age-related changes in DNAm and correlation with gene expression. These results suggest that DNAm may be a proximal mechanism for decreased expression of BDNF, SST, and other BDNF- and GABA-related genes with brain aging and, by extension, for brain disorders in which their expression is decreased.

Neuroanatomical correlates of late-life depression and associated cognitive changes

We compared cortical thickness between patients with late-life depression (LLD) and healthy controls and between patients with early-onset (EOD) and late-onset (LOD) depression. We also tested age effects on cortical thickness in LLD and controls and if cortical thickness and hippocampal volumes were associated with cognitive performance in LLD. Three-dimensional T1-weighted magnetic resonance images were obtained in 49 LLD and 49 matched hospital controls and processed using FreeSurfer. General linear model analysis was used as a statistical approach. LLD group had thinning in the left parahippocampal, fusiform, and inferior-parietal cortex compared with controls. Age correlated with cortical thinning in controls but not in LLD. Women in the LOD groups had extensive cortical thinning in the lateral prefrontal cortex bilaterally compared with EOD women. Absence of statistically significant changes observed in men should however be treated with caution because of the low number of men in the study. Mini-Mental Status Examination score correlated with lateral prefrontal cortical thickness bilaterally and hippocampal volume in the total group of LLD and in LOD but not EOD. LLD is associated with cortical thinning, which is associated with age at depression onset, gender, and level of cognitive functioning.

Depression in later life: a more somatic presentation?

BACKGROUND

Depression later in life may have a more somatic presentation compared with depression earlier in life due to chronic somatic disease and increasing age. This study examines the influence of the presence of chronic somatic diseases and increasing age on symptom dimensions of late-life depression.

METHODS

Baseline data of 429 depressed and non-depressed older persons (aged 60-93 years) in the Netherlands Study of Depression in Old Age were used, including symptom dimension scores as assessed with the mood, somatic and motivation subscales of the Inventory of Depressive Symptomatology-Self Report (IDS-SR). Linear regression was performed to investigate the effect of chronic somatic diseases and age on the IDS-SR subscale scores.

RESULTS

In depressed older persons a higher somatic disease burden was associated with higher scores on the mood subscale (B = 2.02, p = 0.001), whereas higher age was associated with lower scores on the mood (B = -2.30, p < 0.001) and motivation (B = -1.01, p = 0.006) subscales. In depressed compared with non-depressed persons, a higher somatic disease burden showed no different association with higher scores on the somatic subscale (F(1,12) = 9.2; p = 0.003; partial η(2)=0.022).

LIMITATIONS

Because the IDS-SR subscales are specific for old age, it was not feasible to include persons aged < 60 years to investigate differences between earlier and later life.

CONCLUSIONS

It seems that neither higher somatic disease burden nor higher age contributes to more severe somatic symptoms in late-life depression. In older old persons aged ≥ 70 years, late-life depression may not be adequately recognized because they may show less mood and motivational symptoms compared with younger old persons.

Treatment-resistant Late-life Depression: Challenges and Perspectives

The current Review article provides a narrative review about the neurobiological underpinnings and treatment of treatment resistant late-life depression (TRLLD). The manuscript focuses on therapeutic targets of late-life depression, which include pharmacological, psychological, biophysical and exercise treatment approaches. Therefore, we summarize available evidences on that kind of therapies for patients suffering from late-life depression. The search for evidences of therapeutic options of late-life depression were done using searching websites as "pubmed", and using the searching terms "depression", "late-life depression", "treatment", "biophysical therapy", "exercise therapy", "pharmacological therapy" and "psychological therapy". To the end, we summarize and discuss current data, providing some directions for further research. Treatment recommendations for elderly depressive patients favour a multimodal approach, containing psychological, pharmacological and secondary biophysical therapeutic options. Particularly, a combination of psychotherapy and antidepressant medication reflects the best therapeutic option. However, mostly accepted and used is the pharmacological treatment although evidence suggests that the drug therapy is not as effective as it is in younger depressive patients. Further studies employing larger samples and longer follow-up periods are necessary and may focus on comparability of study designs and involve novel approaches to establish the validity and reliability of multimodal treatment programs.

The new DSM-5 diagnosis of mild neurocognitive disorder and its relation to research in mild cognitive impairment

The Diagnostic Statistical Manual-5 (DSM-5) has included a category named the neurocognitive disorder which was formally known in DSM-IV as 'dementia, delirium, amnestic, and other cognitive disorders'. The DSM-5 distinguishes between 'mild' and 'major' neurocognitive disorders. Major neurocognitive disorder replaces the DSM-IV's term 'dementia or other debilitating conditions'. A pivotal addition is 'mild neurocognitive disorder (mNCD)' defined by a noticeable decrement in cognitive functioning that goes beyond normal changes seen in aging. It is a disorder that may progress to dementia - importantly, it may not. Presently, our understanding of mNCD is derived from research on mild cognitive impairment (MCI). Whereas there is currently no clear treatment for mNCD, many experimental therapies now and into the future will focus upon secondary prevention, namely decreasing the risk of progression to major NCD. In this article, we will focus on mNCD by reviewing the relevant literature on MCI. We will review the research on the incidence and prevalence of MCI, conversion rates from MCI to dementia, risk factors for conversion of MCI to dementia, comorbidity of MCI with other neuropsychiatric disorders (NPS), and the development of treatment strategies for neuropsychiatric disorders in MCI. The presence of NPS is common among individuals with MCI and is an important risk for progression to dementia. However, there has been little research on effective treatments for NPS in MCI. Clinicians and investigators must determine if the treatment of the NPS in mNCD will improve quality of life and help reduce the progression of the cognitive impairment.

The moderating effect of age on the 12-month prevalence of anxiety and depressive disorders in adults with a lifetime history of cancer

OBJECTIVE

To determine how age may modulate the association of a history of cancer with a 12-month history of anxiety and depressive disorders.

METHODS

The authors used population-based, cross-sectional surveys, the Collaborative Psychiatric Epidemiology Surveys. These surveys were conducted in the United States in 2001-2003 and included 16,423 adult participants, of whom 702 reported a cancer history. The Composite International Diagnostic Interview evaluated the presence of a 12-month history of anxiety and depressive disorders.

RESULTS

Among those with a cancer history, older adults (≥60 years old) were less likely than younger adults (18-59 years old) to have a 12-month history of an anxiety or depressive disorder. Compared with their peers without cancer, younger adults with a cancer history had more anxiety (23.8% versus 13.9%) and depressive (16.0% versus 9.5%) disorders, whereas older adults with a cancer history had lower levels of anxiety (3.7% versus 6.3%) and depressive (1.9% versus 3.9%) disorders. In multivariable modeling, there was a statistically significant interaction between age group and cancer history, with the risk for anxiety and depressive disorders elevated in the younger age group with a cancer history (odds ratio: 5.84 and odds ratio: 6.13, respectively) but decreased in the older age group with a cancer history (odds ratio: 0.55 and odds ratio: 0.45, respectively).

CONCLUSION

The authors' findings suggest a considerable age-dependent variation with regard to anxiety and depressive disorders in adults with a cancer history. Investigation of the mechanisms contributing to this apparent age differential in risk could have important mental illness treatment implications in this population.

Melancholia in later life: late and early onset differences in presentation, course, and dementia risk

OBJECTIVES

Depression is a risk factor for cognitive decline and dementia. This risk may vary with age of onset and depression subtype. Late onset depression (LOD, 60 years and older) is associated with more cognitive decline, whereas early onset depression (EOD, before 60 years) is associated with more residual depressive symptoms. Potential differences may reflect divergent etiologies. These onset differences, however, have not been examined in the melancholic subtype of depression in older adults.

METHODS

Data were obtained from the Neurocognitive Outcomes of Depression in the Elderly study. Participants (N = 284, 73% EOD-melancholic (EOD-M) and 27% LOD-melancholic (LOD-M)) were followed up over 3 years. Factor analyses examined differences in baseline depressive symptoms. Hierarchical linear growth curve models examined changes in depressive symptoms (Montgomery-Asberg Depression Rating Scale) and cognition (mini mental state examination). An annual clinical review panel assigned diagnoses of dementia.

RESULTS

The LOD-M participants had more vegetative symptoms at baseline. LOD-M exhibited greater cognitive decline but fewer residual depressive symptoms than EOD-M. Among participants who remained in the study for at least 1 year, in uncontrolled analyses, a greater percentage of LOD-M compared with EOD-M developed dementia (23.0% vs. 7.8%). Whereas in logistic analyses, controlling for baseline demographics, age at onset remained a predictor of dementia, the odds ratio suggested that the effect was relatively small.

CONCLUSIONS

The EOD-M and LOD-M participants have a different presentation and course. LOD-M may represent a syndrome of neuropsychiatric deterioration with expression of both depressive symptoms and cognitive decline.

The double burden of age and disease on cognition and quality of life in bipolar disorder

OBJECTIVE

Bipolar disorder (BPD) and normal aging are known to impact cognitive skills and health-related quality of life (HRQOL). This study investigated how aging and disease interact in predicting cognitive and psychosocial outcomes.

METHODS

Eight cognitive and ten subjective HRQOL domain ratings were measured. Subjects included 80 young (18-29 years) and late middle-aged (50-65 years) BPD patients in the euthymic phase and 70 age-equivalent healthy comparison participants.

RESULTS

An age X disease interaction was detected in three domains of cognitive functioning that reflect emotion processing, processing speed, and executive functioning skills, with BPD patients in the older group performing most poorly. There was a double burden of aging and disease on reported ability to perform physical tasks. However, regardless of age, disease status was associated with lower ratings of HRQOL in the psychosocial/affective sphere and the majority of cognitive domains. Post hoc analyses revealed that number of years ill was positively associated with select HRQOL ratings in older, but not younger BPD adults.

CONCLUSIONS

These findings may stimulate future longitudinal study of cognition and quality of life in BPD patients across the life span, focusing on additive and interactive effects of aging and disease burden, which could culminate in developing more effective treatment and rehabilitation strategies for this traditionally challenging to treat population.

Reduced cerebrospinal fluid levels of brain-derived neurotrophic factor is associated with cognitive impairment in late-life major depression

OBJECTIVES

Late-life depression (LLD) is associated with reduced neurotrophic support and abnormalities in neurodegenerative cascades. The aim of the present study is to determine the concentrations of brain-derived neurotrophic factor (BDNF), amyloid-β42, total Tau, and phosphorylated Tau in the cerebrospinal fluid (CSF) of patients with LLD and cognitive impairment compared to healthy older adults.

METHOD

We included 25 antidepressant-free patients with LLD (10 with mild cognitive impairment [LLD + MCI] and 15 with no cognitive decline [LLD + NCD]) and 25 healthy older adults as a comparison group. Depressive symptoms were assessed by the 21-item Hamilton Depression Rating Scale (HDRS-21) and cognitive performance by a comprehensive cognitive battery.

RESULTS

Patients with LLD + MCI showed significantly lower CSF BDNF levels compared to LLD + NCD and healthy controls (p = .003). There were no significant differences in Alzheimer's disease-related CSF biomarkers between groups. CSF BDNF concentrations were positively correlated with Cambridge Cognitive Test (CAMCOG) scores (r = .36, p = .02).

DISCUSSION

The present study adds to the growing body of evidence that abnormalities in the BDNF system are involved in the pathophysiology of LLD. The reduction of the availability of BDNF in the central nervous system may indicate increased vulnerability to the development of several age-related neuropsychiatric disorders as well as to adverse cognitive outcomes.

Comparing profiles of mental disorder across birth cohorts: results from the 2007 Australian National Survey of Mental Health and Wellbeing

OBJECTIVE

To describe and compare individuals with any DSM-IV mental disorder from three different birth cohorts - young (16-34 years), middle age (35-59 years) and older age (60-85 years) - on a range of clinically relevant factors.

METHOD

Data were derived from the 2007 Australian National Survey of Mental Health and Wellbeing. Individuals from three birth cohorts with a range of mental health and substance use disorders were identified using DSM-IV criteria and compared using regression analysis. The specific factors that were compared include: (1) type of disorder/disorders present; (2) suicidality; (3) number of co-occurring disorders; (4) levels of distress and impairment; (5) self-assessed physical and mental health; (6) presence of physical conditions; (7) size and quality of social support/network; and (8) treatment-seeking behaviour.

RESULTS

The birth cohorts differed dramatically in terms of the specific disorders that were present. The older cohort were significantly more likely to experience internalising disorders and significantly less likely to experience externalising disorders in comparison to the young cohort. The older cohort were significantly more likely to experience co-morbid physical conditions as well as lower life satisfaction, poorer self-rated physical health, increased functional impairment, and more days out of role. The younger cohort had a significantly larger peer group that they could confide in and rely on in comparison to the older cohort.

CONCLUSIONS

Clinicians and researchers need to be cognisant that mental disorders manifest as highly heterogeneous constructs. The presentation of a disorder in a younger individual could be vastly different from the presentation of the same disorder in an older individual. The additional burden associated with these factors and how they apply to different birth cohorts must be taken into consideration when planning mental health services and effective treatment for the general population.

A large, cross-sectional observational study of serum BDNF, cognitive function, and mild cognitive impairment in the elderly

Objective: The clinical relationship between brain-derived neurotrophic factor (BDNF) and cognitive function or mild cognitive impairment (MCI) is not well-understood. The purpose of this study was to identify the relationship between serum BDNF and cognitive function and MCI, and determine whether serum BDNF level might be a useful biomarker for assessing risk for MCI in older people.

Materials and Methods: A total of 4463 individuals aged 65 years or older (mean age 72 years) participating in the study. We measured performance in a battery of neuropsychological and cognitive function tests; serum BDNF concentration.

Results: Eight hundred twenty-seven participants (18.8%) had MCI. After adjustment for sex, age, education level, diabetes, and current smoking, serum BDNF was associated with poorer performance in the story memory, and digit symbol substitution task scores. Serum BDNF was marginally associated with the presence of MCI (odds ratio, 95% confidence interval: 1.41, 1.00–1.99) when BDNF was 1.5 SD lower than the mean value standardized for sex and age, education level, diabetes, and current smoking.

Conclusion: Low serum BDNF was associated with lower cognitive test scores and MCI. Future prospective studies should establish the discriminative value of serum BDNF for the risk of MCI.

Antidepressants differentially related to 1,25-(OH)₂ vitamin D₃ and 25-(OH) vitamin D₃ in late-life depression

A low plasma 25-OH vitamin D3 level is a universal risk factor for a wide range of diseases and has also been implicated in late-life depression. It is currently unknown whether the biologically active form of vitamin D, that is, 1,25-(OH)2 vitamin D3, is also decreased in late-life depression, or whether vitamin D levels correlate with specific depression characteristics. We determined plasma 25-OH vitamin D3, 1,25-(OH)2 vitamin D3 and parathormone levels in 355 depressed older persons and 124 non-depressed comparison subjects (age 60 years). Psychopathology was established with the Composite International Diagnostic Interview 2.1, together with potential confounders and depression characteristics (severity, symptom profile, age of onset, recurrence, chronicity and antidepressant drug use). Adjusted for confounders, depressed patients had significantly lower levels of 25-OH vitamin D33 (Cohen's d =0.28 (95% confidence interval: 0.07-0.49), P=0.033) as well as 1,25-(OH)2 vitamin D3 (Cohen's d =0.48 (95% confidence interval: 0.27-0.70), P<0.001) than comparison subjects. Of all depression characteristics tested, only the use of tricyclic antidepressants (TCAs) was significantly correlated with lower 1,25-(OH)2 vitamin D3 levels (Cohen's d =0.86 (95% confidence interval: 0.53-1.19), P<0.001), but not its often measured precursor 25-OH vitamin D3. As vitamin D levels were significantly lower after adjustment for confounders, vitamin D might have an aetiological role in late-life depression. Differences between depressed and non-depressed subjects were largest for the biologically active form of vitamin D. The differential impact of TCAs on 25-OH vitamin D3 and 1,25-(OH)2 vitamin D3 levels suggests modulation of 1-α-hydroxylase and/or 24-hydroxylase, which may in turn have clinical implications for biological ageing mechanisms in late-life depression.

Cognition and psychopathology in nonagenarians and centenarians living in geriatric nursing homes in Switzerland: a focus on anosognosia

BACKGROUND

The number of nonagenarians and centenarians is rising dramatically, and many of them live in nursing homes. Very little is known about psychiatric symptoms and cognitive abilities other than memory in this population. This exploratory study focuses on anosognosia and its relationship with common psychiatric and cognitive symptoms.

METHODS

Fifty-eight subjects aged 90 years or older were recruited from geriatric nursing homes and divided into five groups according to Mini-Mental State Examination scores. Assessment included the five-word test, executive clock-drawing task, lexical and categorical fluencies, Anosognosia Questionnaire-Dementia, Neuropsychiatric Inventory, and Charlson Comorbidity Index.

RESULTS

Subjects had moderate cognitive impairment, with mean ± SD Mini-Mental State Examination being 15.41 ± 7.04. Anosognosia increased with cognitive impairment and was associated with all cognitive domains, as well as with apathy and agitation. Subjects with mild global cognitive decline seemed less anosognosic than subjects with the least or no impairment. Neither anosognosia nor psychopathological features were related to physical conditions.

CONCLUSIONS

Anosognosia in oldest-old nursing home residents was mostly mild. It was associated with both cognitive and psychopathological changes, but whether anosognosia is causal to the observed psychopathological features requires further investigation.

The role of social support in anxiety and depression among Parkinson's disease patients

PURPOSE

To explore how social support is associated with anxiety and depression in Parkinson's disease (PD) patients controlling for gender, disease duration and disease severity.

METHODS

The sample consisted of 124 patients (52.4% male; mean age 68.1 ± 8.4 years; mean disease duration 6.3 ± 5.5 years). Anxiety and depression were measured with the Hospital Anxiety and Depression Scale, social support with the Multidimensional Scale of Perceived Social Support and disease severity with the Unified Parkinson Disease Rating Scale. Data were analyzed using linear regression.

RESULTS

Gender, disease duration, disease severity and social support explained 31% of the total variance in anxiety in younger PD patients but did not significantly contribute to the explanation of depression. In the older group, this model explained 41% of the variance in depression but did not significantly contribute to the explanation of anxiety.

CONCLUSION

PD patients experience the positive influence of social support differently according to age. In the younger group, disease duration plays the primary role regarding anxiety. In the older group, poor social support especially from friends is associated with more depression after controlling for the relevant variables. Implications of Rehabilitation PD is a disease of older age with a neurodegenerative character and treatment should focus on increasing quality of life. Anxiety and depression are common co-morbidities in PD patients. The support network should also be screened regularly and involved in enhancing the quality of life.

Brain-derived neurotrophic factor levels in late-life depression and comorbid mild cognitive impairment: a longitudinal study

Changes in brain-derived neurotrophic factor (BDNF) level are implicated in the pathophysiology of cognitive decline in depression and neurodegenerative disorders in older adults. We aimed to evaluate the longitudinal association over two years between BDNF and persistent cognitive decline in individuals with remitted late-life depression and Mild Cognitive Impairment (LLD + MCI) compared to either individuals with remitted LLD and no cognitive decline (LLD + NCD) or never-depressed, cognitively normal, elderly control participants. We additionally evaluated the effect of double-blind, placebo-controlled donepezil treatment on BDNF levels in all of the remitted LLD participants (across the levels of cognitive function). We included 160 elderly participants in this study (72 LLD + NCD, 55 LLD + MCI and 33 never-depressed cognitively normal elderly participants). At the same visits, cognitive assessments were conducted and blood sampling to determine serum BDNF levels were collected at baseline assessment and after one and two years of follow-up. We utilized repeated measure, mixed effect models to assess: (1) the effects of diagnosis (LLD + MCI, LLD + NCD, and controls), time, and their interaction on BDNF levels; and (2) the effects of donepezil treatment (donepezil vs. placebo), time, baseline diagnosis (LLD + MCI vs. LLD + NCD), and interactions between these contrasts on BDNF levels. We found a significant effect of time on BDNF level (p = 0.02) and a significant decline in BDNF levels over 2 years of follow-up in participants with LLD + MCI (p = 0.004) and controls (p = 0.04). We found no effect of donepezil treatment on BDNF level. The present results suggest that aging is an important factor related to decline in BDNF level. Clinicaltrials.gov Identifier: NCT00177671.

Molecular aging of the brain, neuroplasticity, and vulnerability to depression and other brain-related disorders

The increased risk for neurodegenerative and neuropsychiatric disorders associated with extended lifespan has long suggested mechanistic links between chronological age and brain-related disorders, including depression, Recent characterizations of age-dependent gene expression changes now show that aging of the human brain engages a specific set of biological pathways along a continuous lifelong trajectory, and that the same genes that are associated with normal brain aging are also frequently and similarly implicated in depression and other brain-related disorders. These correlative observations suggest a model of age-by-disease molecular interactions, in which brain aging promotes biological changes associated with diseases, and additional environmental factors and genetic variability contribute to defining disease risk or resiliency trajectories. Here we review the characteristic features of brain aging in terms of changes in gene function over time, and then focus on evidence supporting accelerated molecular aging in depression. This proposed age-by-disease biological interaction model addresses the current gap in research between “normal” brain aging and its connection to late-life diseases. The implications of this model are profound, as it provides an investigational framework for identifying critical moderating factors, outlines opportunities for early interventions or preventions, and may form the basis for a dimensional definition of diseases that goes beyond the current categorical system.

Anticipated brain molecular aging in major depression

OBJECTIVES

Brain molecular aging, the pervasive and consistent transcriptome changes associated with normal brain aging, appears to overlap with disease pathways and may be anticipated in neurodegenerative and neuropsychiatric diseases, including major depressive disorder (MDD). Here, we characterize the global interaction of MDD-related gene changes with age, starting from our previous report of downregulated brain-derived neurotrophic factor (BDNF) and BDNF-dependent genes in the amygdala of women with MDD.

METHODS

A large-scale gene expression data set in the amygdala from a postmortem cohort of 21 women with MDD and 21 age-matched controls (age range: 16-74 years) was analyzed for correlations of gene transcript changes with age, in the presence or absence of a diagnosis of MDD.

RESULTS

1) The age-related decrease in BDNF transcripts observed in control subjects corresponds with further age-related decreases in BDNF and BDNF-dependent gene expression in MDD subjects; 2) most MDD-related genes are frequently age-regulated in both MDD and control subjects; 3) the effects of MDD and age are positively correlated; 4) most genes that are age-dependent in control subjects display greater age effects in MDD subjects; and 5) the increased prevalence of age effects in MDD corresponds to similar trends in controls, rather than representing de novo age effects.

CONCLUSIONS

MDD strongly associates with robust and anticipated gene expression changes that occur during normal aging of the brain, suggesting that an older molecular age of the brain represents an early biological event and/or a marker of risk for subsequent onset of MDD symptoms.

Organic bases of late-life depression: a critical update

Late-life depression (LLD) is frequently associated with cognitive impairment and increases the risk of subsequent dementia. Cerebrovascular disease, deep white matter lesions, Alzheimer disease (AD) and dementia with Lewy bodies (DLB) have all been hypothesized to contribute to this increased risk, and a host of studies have looked at the interplay between cerebrovascular disease and LLD. This has resulted in new concepts of LLD, such as "vascular depression", but despite multiple magnetic resonance imaging (MRI) studies in this field, the relationship between structural changes in human brain and LLD is still controversial. While pathological findings of suicide in some elderly persons revealed multiple lacunes, small vessel cerebrovascular disease, AD-related lesions or multiple neurodegenerative pathologies, recent autopsy data challenged the role of subcortical lacunes and white matter lesions as major morphological substrates of depressive symptoms as well as poorer executive function and memory. Several neuropathological studies, including a personal clinico-pathological study in a small cohort of elderly persons with LLD and age-matched controls confirmed that lacunes, periventricular and deep white matter demyelination as well as AD-related lesions are usually unrelated to the occurrence of LLD. In the same line, neuropathological data show that early-onset depression is not associated with an acceleration of age-related neurodegenerative changes. Very recent data on the critical role of glia-modulating neuronal dysfunction and degeneration in depression are discussed.

Age-by-disease biological interactions: implications for late-life depression

Onset of depressive symptoms after the age of 65, or late-life depression (LLD), is common and poses a significant burden on affected individuals, caretakers, and society. Evidence suggests a unique biological basis for LLD, but current hypotheses do not account for its pathophysiological complexity. Here we propose a novel etiological framework for LLD, the age-by-disease biological interaction hypothesis, based on the observations that the subset of genes that undergoes lifelong progressive changes in expression is restricted to a specific set of biological processes, and that a disproportionate number of these age-dependent genes have been previously and similarly implicated in neurodegenerative and neuropsychiatric disorders, including depression. The age-by-disease biological interaction hypothesis posits that age-dependent biological processes (i) are “pushed” in LLD-promoting directions by changes in gene expression naturally occurring during brain aging, which (ii) directly contribute to pathophysiological mechanisms of LLD, and (iii) that individual variability in rates of age-dependent changes determines risk or resiliency to develop age-related disorders, including LLD. We review observations supporting this hypothesis, including consistent and specific age-dependent changes in brain gene expression and their overlap with neuropsychiatric and neurodegenerative disease pathways. We then review preliminary reports supporting the genetic component of this hypothesis. Other potential biological mediators of age-dependent gene changes are proposed. We speculate that studies examining the relative contribution of these mechanisms to age-dependent changes and related disease mechanisms will not only provide critical information on the biology of normal aging of the human brain, but will inform our understanding of age-dependent diseases, in time fostering the development of new interventions for prevention and treatment of age-dependent diseases, including LLD.