Declining Skeletal Muscle Mitochondrial Function Associated With Increased Risk of Depression in Later Life

Exploring the links of skeletal muscle mitochondrial oxidative capacity, physical functionality, and mental well-being of cancer survivors

Physical impairments following cancer treatment have been linked with the toxic effects of these treatments on muscle mass and strength, through their deleterious effects on skeletal muscle mitochondrial oxidative capacity. Accordingly, we designed the present study to explore relationships of skeletal muscle mitochondrial oxidative capacity with physical performance and perceived cancer-related psychosocial experiences of cancer survivors. We assessed skeletal muscle mitochondrial oxidative capacity using in vivo phosphorus-31 magnetic resonance spectroscopy (31P MRS), measuring the postexercise phosphocreatine resynthesis time constant, τPCr, in 11 post-chemotherapy participants aged 34-70 years. During the MRS procedure, participants performed rapid ballistic knee extension exercise to deplete phosphocreatine (PCr); hence, measuring the primary study outcome, which was the recovery rate of PCr (τPCr). Patient-reported outcomes of psychosocial symptoms and well-being were assessed using the Patient-Reported Outcomes Measurement Information System and the 36-Item Short Form health survey (SF-36). Rapid bioenergetic recovery, reflected through a smaller value of τPCr was associated with worse depression (rho ρ = - 0.69, p = 0.018, and Cohen's d = - 1.104), anxiety (ρ = - 0.61, p = .046, d = - 0.677), and overall mental health (ρ = 0.74, p = 0.010, d = 2.198) scores, but better resilience (ρ = 0.65, p = 0.029), and coping-self efficacy (ρ = 0.63, p = 0.04) scores. This is the first study to link skeletal muscle mitochondrial oxidative capacity with subjective reports of cancer-related behavioral toxicities. Further investigations are warranted to confirm these findings probing into the role of disease status and personal attributes in these preliminary results.

Physical activity, physical frailty and depressive symptoms among Chinese male and female older adults: do different indicators make a difference?

Objectives

Older adults become more inactive and frailer with aging. Physical status is closely linked to mental health, but it is unclear which physical indicator is more strongly associated with depressive symptoms in older adults. The present study aimed to compare relationships between self-reported physical activity, physical frailty (muscle mass, muscle strength, and gait ability) and depressive symptoms in community male and female older adults.

Methods

A total of 1,180 adults aged 60 years and older were recruited to participate in this study from a Chinese community receiving annual check-up service from September 2018 to May 2019. Physical activity was assessed by the International Physical Activity Questionnaire (IPAQ). The Bio-electrical Impedance Analyzer was used to determine the muscle mass. As the indicators of muscle function, grip strength and gait ability were assessed by the dynamometer and Timed Up and Go Test (TUGT), respectively. The 15-item version of Geriatric Depression Scale (GDS-15) was used to examine depressive symptoms. Demographic variables, health status and sleep quality were collected using questionnaire.

Results

11.8% men and 11.9% women reported depressive symptoms. Logistic regression showed that depressive symptoms was associated with low grip strength (OR = 2.42, 95% CI: 1.04-5.63), slow gait ability (OR = 3.60, 95% CI: 1.28-10.13) in older males, and associated with low level of self-reported physical activity (OR = 3.85, 95% CI: 2.00-7.42) in older females. No significant association was found between muscle mass and depressive symptoms.

Conclusion

There were gender differences in the relationship between physical activity, physical frailty, and depressive symptoms. Grip strength and gait ability may be a better indicator of frailty for predicting depressive symptoms in older men while physical activity may be useful in predicting depressive symptoms in older women.

Late-Life Depression is Associated With Increased Levels of GDF-15, a Pro-Aging Mitokine

OBJECTIVE

In older adults, major depressive disorder (MDD) is associated with accelerated physiological and cognitive aging, generating interest in uncovering biological pathways that may be targetable by interventions. Growth differentiation factor-15 (GDF-15) plays a significant role in biological aging via multiple biological pathways relevant to age and age-related diseases. Elevated levels of GDF-15 correlate with increasing chronological age, decreased telomerase activity, and increased mortality risk in older adults. We sought to evaluate the circulating levels of GDF-15 in older adults with MDD and its association with depression severity, physical comorbidity burden, age of onset of first depressive episode, and cognitive performance.

DESIGN

This study assayed circulating levels of GDF-15 in 393 older adults (mean ± SD age 70 ± 6.6 years, male:female ratio 1:1.54), 308 with MDD and 85 non-depressed comparison individuals.

RESULTS

After adjusting for confounding variables, depressed older adults had significantly higher GDF-15 serum levels (640.1 ± 501.5 ng/mL) than comparison individuals (431.90 ± 223.35 ng/mL) (t=3.75, d.f.= 391, p=0.0002). Among depressed individuals, those with high GDF-15 had higher levels of comorbid physical illness, lower executive cognitive functioning, and higher likelihood of having late-onset depression.

CONCLUSION

Our results suggest that depression in late life is associated with GDF-15, a marker of amplified age-related biological changes. GDF-15 is a novel and potentially targetable biological pathway between depression and accelerated aging, including cognitive aging.

Physical exercise and mitochondrial function: New therapeutic interventions for psychiatric and neurodegenerative disorders

Psychiatric and neurodegenerative diseases, including major depression disorder (MDD), bipolar disorder, and Alzheimer's disease, are a burden to society. Deficits of adult hippocampal neurogenesis (AHN) have been widely considered the main hallmark of psychiatric diseases as well as neurodegeneration. Herein, exploring applicable targets for improving hippocampal neural plasticity could provide a breakthrough for the development of new treatments. Emerging evidence indicates the broad functions of mitochondria in regulating cellular behaviors of neural stem cells, neural progenitors, and mature neurons in adulthood could offer multiple neural plasticities for behavioral modulation. Normalizing mitochondrial functions could be a new direction for neural plasticity enhancement. Exercise, a highly encouraged integrative method for preventing disease, has been indicated to be an effective pathway to improving both mitochondrial functions and AHN. Herein, the relative mechanisms of mitochondria in regulating neurogenesis and its effects in linking the effects of exercise to neurological diseases requires a systematic summary. In this review, we have assessed the relationship between mitochondrial functions and AHN to see whether mitochondria can be potential targets for treating neurological diseases. Moreover, as for one of well-established alternative therapeutic approaches, we summarized the evidence to show the underlying mechanisms of exercise to improve mitochondrial functions and AHN.

Association of Molecular Senescence Markers in Late-Life Depression With Clinical Characteristics and Treatment Outcome

IMPORTANCE

Many older adults with depression do not experience remission with antidepressant treatment, and markers of cellular senescence in late-life depression (LLD) are associated with greater severity of depression, greater executive dysfunction, and higher medical illness burden. Since these clinical characteristics are associated with remission in LLD, molecular and cellular senescence abnormalities could be a possible biological mechanism underlying poor treatment response in this population.

OBJECTIVE

To examine whether the senescence-associated secretory phenotype (SASP) index was associated with the likelihood of remission from a depressive episode in older adults.

DESIGN, SETTING, AND PARTICIPANTS

A nonrandomized, open-label clinical trial was conducted between August 2009 and August 2014 in Pittsburgh, Pennsylvania; St Louis, Missouri; and Toronto, Ontario, Canada, with older adults in a current major depressive episode according to the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition, Text Revision) diagnostic criteria. Data from biomarker analyses were reported according to the clinical trial archived plasma samples run in March 2021. Data were analyzed from June to November 2021.

EXPOSURE

Venlafaxine extended release (dose ranging from 37.5 mg to 300 mg daily) for up to 12 weeks.

MAIN OUTCOMES AND MEASURES

The association between a composite biomarker-based index (SASP index) and treatment remission in older adults with major depression was measured using clinical data and blood samples.

RESULTS

There were 416 participants with a mean (SD) age of 60.02 (7.13) years; 64% (265 participants) were self-reported female, and the mean (SD) Montgomery-Asberg Depression Rating Scale score was 26.6 (5.7). Higher SASP index scores were independently associated with higher rates of nonremission, with an increase of 1 unit in the SASP index score increasing the odds of nonremission by 19% (adjusted odds ratio, 1.19; 95% CI, 1.05-1.35; P = .006). In contrast, no individual SASP factors were associated with remission in LLD.

CONCLUSIONS AND RELEVANCE

Using clinical data and blood samples from a nonrandomized clinical trial, the results of this study suggest that molecular and cellular senescence, as measured with the SASP index, is associated with worse treatment outcomes in LLD. Combining this index score reflecting interrelated biological processes with other molecular, clinical, and neuroimaging markers may be useful in evaluating antidepressant treatment outcomes. These findings inform a path forward for geroscience-guided interventions targeting senescence to improve remission rates in LLD.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT00892047.

Frailty and Depression in Late Life: A High-Risk Comorbidity With Distinctive Clinical Presentation and Poor Antidepressant Response

BACKGROUND

To investigate the longitudinal relationship between physical frailty, the clinical representation of accelerated biological aging, and antidepressant medication response in older adults with depressive illness.

METHODS

An 8-week randomized placebo-controlled trial (escitalopram or duloxetine) followed by 10 months of open antidepressant medication treatment (augmentation, switch strategies) was conducted in an outpatient research clinic. 121 adults aged 60 years or older with major depressive disorder (MDD) or persistent depressive disorder and a 24-item Hamilton Rating Scale for Depression (HRSD) ≥16 were enrolled. Primary measures assessed serially over 12 months include response (50% reduction from baseline HRSD score), remission (HRSD score <10), and frailty (non/intermediate frail [0-2 deficits] vs frail [≥3 deficits]); latent class analysis was used to classify longitudinal frailty trajectories.

RESULTS

A 2-class model best fit the data, identifying a consistently low frailty risk (63% of the sample) and consistently high frailty risk (37% of the sample) trajectory. Response and remission rates (ps ≤ .002) for adults in the high-risk frailty class were at least 21 percentage points worse than those in the low-risk class over 12 months. Furthermore, subsequent frailty was associated with previous frailty (ps ≤ .01) but not previous response or remission (ps ≥ .10).

CONCLUSIONS

Antidepressant medication is poorly effective for MDD occurring in the context of frailty in older adults. Furthermore, even when an antidepressant response is achieved, this response does little to improve their frailty. These data suggest that standard psychiatric assessment of depressed older adults should include frailty measures and that novel therapeutic strategies to address comorbid frailty and depression are needed.

Increased Levels of Circulating Cell-Free mtDNA in the Plasma of Subjects With Late-Life Depression and Frailty: A Preliminary Study

OBJECTIVE

To evaluate the circulating cell-free mitochondrial DNA (ccf-mtDNA) levels, a marker of cellular stress and damage, in older adults with late-life depression (LLD) and frailty. We hypothesize that individuals with both frailty and LLD will have higher ccf-mtDNA levels than individuals with either condition in isolation.

METHODS

Fifty-three older adults (Never Depressed+Robust (reference group, n = 16), LLD+Robust (n = 9), Never Depressed+Prefrail/Frail (n = 5), and LLD+Prefrail/Frail (n = 23)) were included in the study. DNA was extracted from EDTA plasma samples, and ccf-mtDNA was quantified by RT-PCR.

RESULTS

We found a statistically significant difference in the levels of ccf-mtDNA across groups (F_(3,49) = 3.07, p = 0.036), with individuals in the LLD+Prefrail/Frail group showing the highest levels of ccf-mtDNA.

CONCLUSION

The coexistence of LLD and frailty is associated with increased markers of cellular damage and stress (i.e., ccf-mtDNA). Our results suggest that these conditions may share cellular stress and mitochondrial dysfunction phenomena as a common biological mechanism, offering potential future opportunities for geroscience-guided interventions for these conditions.

Biological, Psychological, and Social Determinants of Depression: A Review of Recent Literature

Depression is one of the leading causes of disability, and, if left unmanaged, it can increase the risk for suicide. The evidence base on the determinants of depression is fragmented, which makes the interpretation of the results across studies difficult. The objective of this study is to conduct a thorough synthesis of the literature assessing the biological, psychological, and social determinants of depression in order to piece together the puzzle of the key factors that are related to this condition. Titles and abstracts published between 2017 and 2020 were identified in PubMed, as well as Medline, Scopus, and PsycInfo. Key words relating to biological, social, and psychological determinants as well as depression were applied to the databases, and the screening and data charting of the documents took place. We included 470 documents in this literature review. The findings showed that there are a plethora of risk and protective factors (relating to biological, psychological, and social determinants) that are related to depression; these determinants are interlinked and influence depression outcomes through a web of causation. In this paper, we describe and present the vast, fragmented, and complex literature related to this topic. This review may be used to guide practice, public health efforts, policy, and research related to mental health and, specifically, depression.

Mitochondrial DNA copy number and heteroplasmy load correlate with skeletal muscle oxidative capacity by P31 MR spectroscopy

The association between blood‐based estimates of mitochondrial DNA parameters, mitochondrial DNA copy number (mtDNA‐CN) and heteroplasmy load, with skeletal muscle bioenergetic capacity was evaluated in 230 participants of the Baltimore Longitudinal Study of Aging (mean age:74.7 years, 53% women). Participants in the study sample had concurrent data on muscle oxidative capacity (τ_PCr) assessed by ³¹P magnetic resonance spectroscopy, and mitochondrial DNA parameters estimated from whole‐genome sequencing data. In multivariable linear regression models, adjusted for age, sex, extent of phosphocreatine (PCr) depletion, autosomal sequencing coverage, white blood cell total, and differential count, as well as platelet count, mtDNA‐CN and heteroplasmy load were not significantly associated with τ_PCr (both p > 0.05). However, in models evaluating whether the association between mtDNA‐CN and τ_PCr varied by heteroplasmy load, there was a significant interaction between mtDNA‐CN and heteroplasmy load (p = 0.037). In stratified analysis, higher mtDNA‐CN was significantly associated with lower τ_PCr among participants with high heteroplasmy load (n = 84, β (SE) = −0.236 (0.115), p‐value = 0.044), but not in those with low heteroplasmy load (n = 146, β (SE) = 0.046 (0.119), p‐value = 0.702). Taken together, mtDNA‐CN and heteroplasmy load provide information on muscle bioenergetics. Thus, mitochondrial DNA parameters may be considered proxy measures of mitochondrial function that can be used in large epidemiological studies, especially when comparing subgroups.

Frailty Worsens Antidepressant Treatment Outcomes in Late Life Depression

OBJECTIVE

To investigate the relationship between frailty and treatment response to antidepressant medications in adults with late life depression (LLD).

METHODS

Data were evaluated from 100 individuals over age 60 years (34 men, 66 women) with a depressive diagnosis, who were assessed for frailty at baseline (characteristics include gait speed, grip strength, activity levels, fatigue, and weight loss) and enrolled in an 8-week trial of antidepressant medication followed by 10 months of open-treatment.

RESULTS

Frail individuals (n = 49 with ≥3 deficits in frailty characteristics) did not differ at baseline from the non/intermediate frail (n = 51 with 0-2 deficits) on demographic, medical comorbidity, cognitive, or depression variables. On average, frail individuals experienced 2.82 fewer Hamilton Rating Scale for Depression (HRSD) points of improvement (t = 2.12, df 89, p = 0.037) than the non/intermediate frail over acute treatment, with this difference persisting over 10 months of open-treatment. Weak grip strength and low physical activity levels were each associated with decreased HRSD improvement, and lower response and remission rates over the course of the study. Despite their poorer outcomes, frail individuals received more antidepressant medication trials than the non/intermediate frail.

CONCLUSION

Adults with LLD and frailty have an attenuated response to antidepressant medication and a greater degree of disability compared to non/intermediate frail individuals. This disability and attenuated response remain even after receiving a greater number of antidepressant medication trials. Future research must focus on understanding the specific pathophysiology associated with the frail-depressed phenotype to permit the design and implementation of precision medicine interventions for this high-risk population.

Grip strength and depressive symptoms in a large-scale adult population: The TCLSIH cohort study

BACKGROUND

Previous studies suggest that muscle-derived cytokines (myokines) are linked with brain function. Although muscle strength measured by handgrip strength is a prognostic indicator of functional decline, epidemiological studies directly examining the association between grip strength and mental health remain scarce. The aim of this study is to clarify the association between grip strength and depressive symptoms in the general adult population.

METHODS

This is a cross-sectional study of 24,109 Chinese adults (41. 5  ± 11.9 years; 46.0% females). Grip strength was measured by dynamometer and the greatest force was normalized to body weight (NGS, kg/kg). Depressive symptoms were assessed using the Self-Rating Depression Scale (SDS). Models of logistic regression were conducted to assess the association between NGS and depressive symptoms, with adjustment for established confounding factors.

RESULTS

Of the 24,109 participants, the prevalence of depressive symptoms (SDS ≥45) was 16.8% (males 15.7%, females 18.0%). After adjusting for multiple confounding factors, the odds ratios and 95% confidence interval for depressive symptoms in the quartiles of NGS were 1.00, 0.96 (0.84-1.10), 0.91 (0.79-1.05), and 0.91 (0.78-1.07) (P = 0.03) in males; 1.00, 0.92 (0.80-1.06), 0.90 (0.77-1.04), and 0.80 (0.69-0.94) (P = 0.0002) in females, respectively.

LIMITATIONS

This cross-sectional study cannot determine causality.

CONCLUSIONS

Grip strength was inversely associated with depressive symptoms, with stronger association observed among females than males.  Further prospective studies or randomized trials are required to clarify these findings.