Association of Mitochondrial DNA Copy Number With Brain MRI Markers and Cognitive Function: A Meta-analysis of Community-Based Cohorts

Association of life's essential 8 with leukocyte telomere length and mitochondrial DNA copy number: Findings from the population-based UK Biobank study

OBJECTIVES

To explore the association of Life's Essential 8 (LE8) levels with leukocyte telomere length (LTL) and mitochondrial DNA copy number (mtDNA-CN).

DESIGN

A cross-sectional study.

SETTING AND PARTICIPANTS

225,692 participants aged 37-73 year from the UK Biobank cohort enrolled from 2006 to 2010.

MEASUREMENTS

The LE8 score (0-100) was divided into low (<50), moderate (50-79), and high cardiovascular health (CVH) (≥80) categories, based on health behaviors and factors defined by the American Heart Association. LTL was measured by a validated quantitative polymerase chain reaction method. mtDNA-CN was reacted by standardized SNP probe intensities. The association of CVH (as both a continuous and categorical variable) with LTL and mtDNA-CN was examined using multiple linear regression.

RESULTS

Of 225,692 participants, 5.3% had low CVH, 81.2% had moderate CVH, and 13.4% had high CVH. Participants with higher CVH were usually younger, female, better educated, of higher socioeconomic status, and with a lower prevalence of comorbidities. After adjusting for confounders, a higher LE8 score is associated with longer LTL (Beta = 0.075, P < 0.05) and increased mtDNA-CN (Beta = 0.094, P < 0.05). We also observed that this association was evident in the health behavior score (diet, physical activity, nicotine exposure, and sleep) and the health factors score (BMI, non-HDL cholesterol, blood glucose, and blood pressure), with a stronger positive association of health factors with LTL and mtDNA-CN (Beta = 0.019, P < 0.05; Beta = 0.037, P < 0.05).

CONCLUSIONS

Higher CVH is associated with longer LTL and increased mtDNA-CN.

Mitochondrial DNA copy number and Alzheimer's disease and Parkinson disease

INTRODUCTION

A systematic review on the association of mitochondrial DNA copy number (mtDNA-CN) with Alzheimer's disease (AD) and Parkinson disease (PD) is lacking and the causal relationship remains unclear.

OBJECTIVE

We aimed to conduct a systematic review of observational studies on the association of mtDNA-CN with AD and PD and perform a bidirectional 2-sample Mendelian randomization (MR) study to investigate their causal relationships.

METHODS

PubMed, Embase, and Web of Science were searched for eligible studies before Jan 2025. The causal links were conducted with inverse-variance weighted (IVW) method as the main analysis.

RESULTS

Fourteen case-control and 2 cohort studies investigated the association between mtDNA-CN and AD, with 13 reporting decreased mtDNA-CN associated with increased risk of AD and 3 showing no significant association. All the studies (9 case-control, 1 cross-sectional, 2 cohort studies) observed the relation between mtDNA-CN and PD except for 3 studies reporting no significant association. In MR analysis, genetically predicted mtDNA-CN was not associated with AD and PD, whereas genetically predicted AD (β -0.085, 95 % CI -0.156 to -0.013; P = 0.02) but not PD was associated with mtDNA-CN. Sensitivity and replication analyses showed a stable finding.

DISCUSSION

The systematic review found limited observational studies on mtDNA-CN and AD and PD and majority were case-control study. Findings of the bidirectional MR study did not support a causal effect of mtDNA-CN in the development of AD and PD but found that AD can lead to decreased levels of mtDNA-CN, which suggest mtDNA-CN as a potential biomarker of AD.

The neuroimmune nexus: unraveling the role of the mtDNA-cGAS-STING signal pathway in Alzheimer's disease

The relationship between Alzheimer's disease (AD) and neuroimmunity has gradually begun to be unveiled. Emerging evidence indicates that cyclic GMP-AMP synthase (cGAS) acts as a cytosolic DNA sensor, recognizing cytosolic damage-associated molecular patterns (DAMPs), and inducing the innate immune response by activating stimulator of interferon genes (STING). Dysregulation of this pathway culminates in AD-related neuroinflammation and neurodegeneration. A substantial body of evidence indicates that mitochondria are involved in the critical pathogenic mechanisms of AD, whose damage leads to the release of mitochondrial DNA (mtDNA) into the extramitochondrial space. This leaked mtDNA serves as a DAMP, activating various pattern recognition receptors and immune defense networks in the brain, including the cGAS-STING pathway, ultimately leading to an imbalance in immune homeostasis. Therefore, modulation of the mtDNA-cGAS-STING pathway to restore neuroimmune homeostasis may offer promising prospects for improving AD treatment outcomes. In this review, we focus on the mechanisms of mtDNA release during stress and the activation of the cGAS-STING pathway. Additionally, we delve into the research progress on this pathway in AD, and further discuss the primary directions and potential hurdles in developing targeted therapeutic drugs, to gain a deeper understanding of the pathogenesis of AD and provide new approaches for its therapy.

Mitochondrial DNA Copy Number as a Potential Biomarker for the Severity of Motor Symptoms and Prognosis in Parkinson's Disease

BACKGROUND

Mitochondrial function influences Parkinson's disease (PD) through the accumulation of pathogenic alpha-synuclein, oxidative stress, impaired autophagy, and neuroinflammation. The mitochondrial DNA copy number (mtDNA-CN), representing the number of mitochondrial DNA copies within a cell, serves as an easily assessable proxy for mitochondrial function.

OBJECTIVE

This study aimed to assess the diagnostic and prognostic capabilities of mtDNA-CN in PD.

METHODS

We assessed mtDNA-CN in blood samples using whole genome sequencing from 405 patients with PD and 200 healthy controls (HC). We examined the relationship between mtDNA-CN levels and motor symptom severity in PD, as well as their association with dementia development in patients with early-PD (within 3 years of diagnosis).

RESULTS

mtDNA-CN levels were significantly lower in patients with PD compared with HC (P = 1.1 × 10-5). A negative correlation was discovered between mtDNA-CN level and motor severity in PD (correlation coefficient = -0.20; P = 0.008). Among 210 patients with early-PD, Cox regression analysis demonstrated an association between lower mtDNA-CN levels and a higher risk of developing dementia (hazard ratio [HR] = 0.41, 95% confidence interval: 0.20-0.86, P = 0.02), even after adjusting for age and blood cell count (HR = 0.41, 95% confidence interval: 0.18-0.92, P = 0.03). However, mtDNA-CN levels did not significantly correlate with motor progression in PD.

CONCLUSION

Our findings suggest that blood mtDNA-CN may function as a diagnostic biomarker for PD and a prognostic marker for dementia in patients with PD. © 2025 International Parkinson and Movement Disorder Society.

Mitochondrial DNA copy number associated dementia risk by somatic mutations and frailty

Mitochondrial dysfunction is linked to physical impairment and dementia. Mitochondrial DNA copy number (mtDNAcn) from blood may predict cognitive decline and dementia risk, but the effect of somatic mutations or frailty is unknown. We estimated mtDNAcn using fastMitoCalc and microheteroplasmies using mitoCaller, from Whole Genome Sequencing (WGS) data. In 189,566 participants free of dementia at study entry (mean age = 56 ± 8), we examined the association between mtDNAcn and subsequent dementia diagnosis using Cox regression. Cognition was assessed in a subset on average 8.9 years later. We examined the associations between mtDNAcn and cognitive measures using multivariable linear regression, adjusted for demographic factors, mtDNAcn-related parameters, and apolipoprotein E ε4 status. We further stratified by frailty and microheteroplasmies. Over an average follow-up of 13.2 years, 3533 participants developed dementia. Each SD higher mtDNAcn (16) was associated with 4.2% lower all-cause dementia hazard (HR = 0.958, p = 0.030), 6% lower non-AD dementia hazard (HR = 0.933, p = 0.022), and not-AD dementia hazard. The associations between mtDNAcn and all-cause dementia and non-AD dementia were stronger among those who were pre-frail or frail or with higher microheteroplasmies. Higher mtDNAcn was associated with higher DSST scores (p = 0.036) and significant only among those with higher microheteroplasmies or frailty (p = 0.029 and 0.048, respectively). mtDNAcn was also associated with delta TMT and paired associate learning only in pre-frail/frail participants (p = 0.007 and 0.045, respectively). Higher WGS-based mtDNAcn in human blood is associated with lower dementia risk, specifically non-AD dementia, and specific cognitive function. The relationships appear stronger in high somatic mutations or frailty. Future studies are warranted to investigate biological underpinnings.

Mitochondrial DNA abundance and circulating metabolomic profiling: Multivariable-adjusted and Mendelian randomization analyses in UK Biobank

BACKGROUND

Low leukocyte mitochondrial DNA (mtDNA) abundance has been associated with a higher risk of atherosclerotic cardiovascular disease, but through unclear mechanisms. We aimed to investigate whether low mtDNA abundance is associated with worse metabolomic profiling, as being potential intermediate phenotypes, using cross-sectional and genetic studies.

METHODS

Among 61,186 unrelated European participants from UK Biobank, we performed multivariable-adjusted linear regression analyses to examine the associations between mtDNA abundance and 168 NMR-based circulating metabolomic measures and nine metabolomic principal components (PCs) that collectively covered 91.5% of the total variation of individual metabolomic measures. Subsequently, we conducted Mendelian randomization (MR) to approximate the causal effects of mtDNA abundance on the individual metabolomic measures and their metabolomic PCs.

RESULTS

After correction for multiple testing, low mtDNA abundance was associated with 130 metabolomic measures, predominantly lower concentrations of some amino acids and higher concentrations of lipids, lipoproteins and fatty acids; moreover, mtDNA abundance was associated with seven out of the nine metabolomic PCs. Using MR, genetically-predicted low mtDNA abundance was associated with lower lactate (standardized beta and 95% confidence interval: -0.17; -0.26, -0.08), and higher acetate (0.15; 0.07,0.23), and unsaturation degree (0.14; 0.08,0.20). Similarly, genetically-predicted low mtDNA abundance was associated with lower metabolomic PC2 (related to lower concentrations of lipids and fatty acids), and higher metabolomic PC9 (related to lower concentrations of glycolysis-related metabolites).

CONCLUSION

Low mtDNA abundance is associated with metabolomic perturbations, particularly reflecting a pro-atherogenic metabolomic profile, which potentially could link low mtDNA abundance to higher atherosclerosis risk.

Mitochondrial DNA abundance in blood is associated with Alzheimer's disease- and dementia-risk

The mitochondrial cascade hypothesis of Alzheimer's disease (AD) has been portrayed through molecular, cellular, and animal studies; however large epidemiological studies are lacking. This study aimed to explore the association of mitochondrial DNA copy number (mtDNAcn), a marker representative of mtDNA abundance per cell, with risk of incident all-cause dementia, AD, and vascular dementia diagnosis within 17 years and dementia-related blood biomarkers (P-tau181, GFAP, and NfL). Additionally, sex-stratified analyses were completed. In this German population-based cohort study (ESTHER), 9940 participants aged 50-75 years were enrolled by general practitioners and followed for 17 years. Participants were included in this study if information on dementia status and blood-based mtDNAcn measured via real-time polymerase chain reaction were available. In a nested case-control approach, a subsample of participants additionally had measurements of P-tau181, GFAP, and NfL in blood samples taken at baseline. Of 4913 participants eligible for analyses, 386 were diagnosed with incident all-cause dementia, including 130 AD and 143 vascular dementia cases, while 4527 participants remained without dementia diagnosis within 17 years. Participants with low mtDNAcn (lowest 10%) experienced 45% and 65% percent increased risk of incident all-cause dementia and AD after adjusting for age and sex (all-cause dementia: HRadj, 95%CI:1.45, 1.08-1.94; AD: HRadj, 95%CI: 1.65, 1.01-2.68). MtDNAcn was not associated to vascular dementia diagnosis and was more strongly associated with all-cause dementia among women. In the nested case-control study (n = 790), mtDNAcn was not significantly associated with the dementia-related blood biomarkers (P-tau181, GFAP, and NfL) levels in blood from baseline before dementia diagnosis. This study provides novel epidemiological evidence connecting mtDNA abundance, measured via mtDNAcn, to incident dementia and AD at the population-based level. Reduced mitochondrial abundance may play a role in pathogenesis, especially among women.

Mitochondrial DNA copy number as a mediator of the relationship between insulin resistance and cognitive function in patients with euthymic bipolar disorder

Persistent cognitive challenges in bipolar disorder (BD) may be tied to insulin resistance, which crucially affects both metabolism and brain health. Additionally, mitochondrial DNA (mtDNA) copy number has emerged as an indicator of cognitive performance and response to treatment in BD. However, it remains unclear whether and how this indicator might serve as a bridge between metabolic dysfunction and cognitive capacity. In 68 study participants with euthymic BD, insulin resistance was assessed according to fasting glucose and insulin levels. mtDNA copy number was quantified from leukocytes, and executive function was measured with the Wisconsin card-sorting test (WCST). Mediation models were applied to explore the statistical relationship between insulin resistance, mtDNA copy number, and executive function. Both linear regression and Poisson distribution approaches with robust bootstrap simulations were used for significance testing. The results indicated that insulin resistance indirectly affects executive function via mtDNA copy number. This mediation relationship was statistically significant for both preservation errors and completion of categories in the WCST, although there were no significant direct effects of insulin resistance on the executive functions. We therefore concluded that insulin resistance is associated with reduced mtDNA copy number in blood, which may negatively impact executive functions in patients with euthymic BD. Further work is warranted to determine if improving metabolic and mitochondrial health may lead to better cognitive outcomes in BD.

Higher skeletal muscle mitochondrial oxidative capacity is associated with preserved brain structure up to over a decade

Impaired muscle mitochondrial oxidative capacity is associated with future cognitive impairment, and higher levels of PET and blood biomarkers of Alzheimer's disease and neurodegeneration. Here, we examine its associations with up to over a decade-long changes in brain atrophy and microstructure. Higher in vivo skeletal muscle oxidative capacity via MR spectroscopy (post-exercise recovery rate, kPCr) is associated with less ventricular enlargement and brain aging progression, and less atrophy in specific regions, notably primary sensorimotor cortex, temporal white and gray matter, thalamus, occipital areas, cingulate cortex, and cerebellum white matter. Higher kPCr is also associated with less microstructural integrity decline in white matter around cingulate, including superior longitudinal fasciculus, corpus callosum, and cingulum. Higher in vivo muscle oxidative capacity is associated with preserved brain structure up to over a decade, particularly in areas important for cognition, motor function, and sensorimotor integration.

White Matter Imaging Phenotypes Mediate the Negative Causality of Mitochondrial DNA Copy Number on Sleep Apnea: A Bidirectional Mendelian Randomization Study and Mediation Analysis

Purpose

Sleep apnea (SA), associated with absent neural output, is characterised by recurrent episodes of hypoxemia and repeated arousals during sleep, resulting in decreased sleep quality and various health complications. Mitochondrial DNA copy number (mtDNA-CN), an easily accessible biomarker in blood, reflects mitochondrial function. However, the causal relationship between mtDNA-CN and SA remains unclear. This study aimed to investigate the causality between mtDNA-CN and SA while identifying potential mediating brain imaging phenotypes (BIPs).

Methods

Two-sample bidirectional Mendelian randomisation (MR) analysis was performed to estimate the causal relationship between mtDNA-CN and SA, with further validation using Bayesian framework-based MR analysis. A two-step approach was employed to evaluate causal relationships between BIPs, mtDNA-CN and SA, utilising the "product of coefficients" method to assess the mediating effects of BIPs. Multiple testing errors were corrected using the Benjamini-Hochberg method.

Results

Genetically predicted mtDNA-CN had a negative causal effect on SA (OR = 0.859, 95% CI = 0.785-0.939, P = 3.20×10-4), whereas SA did not have a causal effect on mtDNA-CN (OR = 1.0056, 95% CI = 0.9954-1.0159, P = 0.2825). Among 3935 BIPs, two features related to white matter microstructure served as partial mediators: the second eigenvalue from diffusion MRI data analysed by tract-based spatial statistics in the right posterior thalamic radiation, with a mediation proportion of 11.37% (P = 0.0450), and fractional anisotropy in the right sagittal stratum, with a mediation proportion of 12.79% (P = 0.0323).

Conclusion

This study demonstrated a causal relationship between mtDNA-CN and SA, with specific brain white matter microstructure phenotypes potentially acting as mediators. These findings highlight the potential of mtDNA-CN as a biomarker for SA and underscore its relevance in guiding future therapeutic strategies targeting mitochondrial health and brain white matter microstructure.

The mitochondrial function of peripheral blood cells in cognitive frailty patients

Background

Cognitive frailty (CF), characterized by the coexistence of physical frailty and cognitive impairment, is linked to increased morbidity and mortality in older adults. While CF has been linked to multiple physiological and lifestyle factors, the underlying biological mechanisms remain poorly understood. This study investigated the risk factors for CF and explored the relationship between mitochondrial function and CF in hospitalized patients.

Methods

A total of 279 hospitalized individuals were recruited from December 2020 to August 2022, conducted comprehensive clinical assessments, and collected peripheral blood samples. CF was evaluated using the Physical Frailty Phenotype and Montreal Cognitive Assessment scales. Nutritional status was assessed with the Mini Nutritional Assessment, and depression was measured using the Geriatric Depression Scale. DNA was obtained from the peripheral blood and interrogated for mitochondrial DNA copy number (mtDNAcn). Peripheral blood mononuclear cells isolated from peripheral blood were examined for respiratory function and reactive oxygen species (ROS) levels. Additionally, plasma samples were analyzed for inflammatory markers and Carnitine Palmitoyltransferase II (CPT2).

Results

Among the participants, 90 were classified as CF and 46 as non-CF. Logistic regression analysis revealed that increased age (OR 1.156, 95% CI 1.064-1.255), lower educational attainment (OR 0.115, 95% CI 0.024-0.550), malnutrition (OR 0.713, 95% CI 0.522-0.973), and higher depression scores (OR 1.345, 95% CI 1.065-1.699) were significantly associated with CF. The independent t tests and Mann-Whitney U tests showed the CF group exhibited impaired mitochondrial function, characterized by reduced mtDNAcn and respiratory activity, coupled with elevated ROS, interleukin-6, and CPT2 levels compared with the non-CF group. After adjusted for age, sex, and BMI, compared with non-CF group, the OR values for the CF group of mtDNAcn and ROS were 0.234 (95% CI = 0.065-0.849) (p = 0.027) and 1.203 (95% CI = 1.075-1.347) (p = 0.001), respectively. The Sensitive analysis showed that the area under curve values for mtDNAcn and ROS were 0.653 and 0.925.

Conclusion

Age, lower educational attainment, malnutrition, and depression are significant risk factors for CF. Moreover, mitochondrial dysfunction, characterized by decreased mtDNAcn, impaired respiratory function and increased ROS levels appears to be a critical phenotype of CF.

Biospecimens in the HEALthy Brain and Child Development (HBCD) Study: Rationale and protocol

The HEALthy Brain and Child Development (HBCD) Study, a multi-site prospective longitudinal cohort study, will examine human brain, cognitive, behavioral, social, and emotional development beginning prenatally and planned through early childhood. The longitudinal collection of biological samples from over 7000 birthing parents and their children within the HBCD study enables research on pre- and postnatal exposures (e.g., substance use, toxicants, nutrition), and biological processes (e.g., genetics, epigenetic signatures, proteins, metabolites) on neurobehavioral developmental outcomes. The following biosamples are collected from the birthing parent: 1) blood (i.e., whole blood, serum, plasma, buffy coat, and dried blood spots) during pregnancy, 2) nail clippings during pregnancy and one month postpartum, 3) urine during pregnancy, and 4) saliva during pregnancy and at in-person postnatal assessments. The following samples are collected from the child at in-person study assessments: 1) saliva, 2) stool, and 3) urine. Additionally, placenta tissue, cord blood, and cord tissue are collected by a subset of HBCD sites. Here, we describe the rationale for the collection of these biospecimens, their current and potential future uses, the collection protocol, and collection success rates during piloting. This information will assist research teams in the planning of future studies utilizing this collection of biological samples.

Curcumin mitigates sodium fluoride toxicity in Caenorhabditis elegans

Fluoride, a naturally occurring element found in water, soil, food, and atmospheric precipitation, can lead to fluorosis and various health issues when consumed excessively. However, the mechanism of fluorosis is still under investigation. This study utilizes Caenorhabditis elegans as a model organism to investigate the effects of fluoride exposure on biological systems and to explore the mechanisms by which curcumin mitigates fluoride-induced toxicity. Three groups were established: a blank control, a sodium fluoride (NaF) exposure group (concentration 5 mmol/L), and a curcumin intervention group (concentration 25 μmol/L). Physiological parameters, lipofuscin levels, intracellular reactive oxygen species (ROS) levels, mitochondrial membrane potential, and mitochondrial copy numbers were measured to assess the effects of fluoride toxicity and curcumin protection. RNA-seq and qRT-PCR were utilized to investigate the molecular mechanisms underlying fluoride-induced damage and curcumin's mitigating effects. Results indicated that fluoride-exposed nematodes displayed physiological abnormalities, increased ROS production, higher lipofuscin levels, altered mitochondrial membrane potential and mitochondrial copy number, and activated MAPK signaling pathway genes. Curcumin exhibited protective effects on these parameters, suggesting its potential in preventing fluoride-induced harm by modulating oxidative stress and preserving mitochondrial function. This research enhances our understanding of the mechanisms of fluoride toxicity and highlights the potential benefits of curcumin.

Mitochondrial DNA copy number and neurocognitive outcomes in children

BACKGROUND

Low mitochondria DNA copy number (mtDNAcn) has been linked to cognitive decline. However, the role of mtDNAcn in healthy cognitive development is unclear. We hypothesized early-life mtDNAcn would be associated with children's learning and memory.

METHODS

We quantified mtDNAcn in umbilical cord blood and child blood at ages 5-7 from participants in a prospective birth cohort. We administered the Children's Memory Scale (CMS) at ages 9-14 (N = 342) and the Wechsler Intelligence Scale for Children (WISC-IV) at ages 7 and 9 (N = 457). Associations between mtDNAcn tertiles and CMS and WISC were evaluated with linear regression and linear mixed-effects models, respectively. We examined non-linear associations using generalized additive mixed models.

RESULTS

Relative to the middle tertile of mtDNAcn, lower childhood mtDNAcn was associated with lower WISC Working Memory (β = -2.65, 95% CI [-5.24, -0.06]) and Full-Scale IQ (β = -3.71 [-6.42, -1.00]), and higher CMS Visual Memory (β = 4.70 [0.47, 8.93]). Higher childhood mtDNAcn was linked to higher CMS Verbal Memory (β = 7.75 [2.50, 13.01]). In non-linear models, higher childhood mtDNAcn was associated with lower WISC Verbal Comprehension.

CONCLUSIONS

Our study provides novel evidence that mtDNAcn measured in childhood is associated with children's neurocognitive performance. mtDNAcn may be a marker of healthy child development.

IMPACT

Mitochondrial DNA copy number (mtDNAcn) may serve as a biomarker for early-life neurocognitive performances in the children's population. Both low and high mtDNAcn may contribute to poorer neurocognition, reflected through learning and memory abilities. This research elucidated the importance of investigating mitochondrial biomarkers in healthy populations and facilitated advancements of future studies to better understand the associations between mitochondrial markers and adverse children's health outcomes.

Mitochondrial dysfunction gene expression, DNA methylation, and inflammatory cytokines interaction activate Alzheimer's disease: a multi-omics Mendelian randomization study

BACKGROUND

Mitochondrial dysfunction (MD) is increasingly recognized as a key pathophysiological contributor in Alzheimer disease (AD). As differential MD genes expression may serve as either a causative factor or a consequence in AD, and expression of these genes could be influenced by epigenetic modifications or interact with inflammatory cytokines, hence, the precise role of MD in AD remains uncertain.

METHODS

Meta-analysis of brain transcriptome datasets was conducted to pinpoint differentially expressed genes (DEGs) associated with MD in AD. We utilized three-step SMR to analyze the AD genome-wide association study summaries with expression quantitative trait loci (eQTLs) and DNA methylation QTLs from the blood and brain tissues, respectively. Through SMR and colocalization analysis, we further explored the interactions between brain eQTLs and inflammatory cytokines.

RESULTS

Five datasets were meta-analyzed to prioritize 825 DEGs in AD from 1339 MD-related genes. Among these, seven genes from blood samples such as NDUFS8 and SPG7 and thirty-two genes from brain tissue including CLU and MAPT were identified as candidate AD-causal MD genes and regulated by methylation level. Furthermore, we revealed 13 MD gene expression-inflammatory pathway pairs involving LDLR, ACE and PTPMT1 along with interleukin-17C, interleukin-18 and hepatocyte growth factor.

CONCLUSIONS

This study highlighted that the AD-causal MD genes could be regulated by epigenetic changes and interact with inflammatory cytokines, providing evidence for AD prevention and intervention.

Plasma metabolomic markers underlying skeletal muscle mitochondrial function relationships with cognition and motor function

BACKGROUND

Lower skeletal muscle mitochondrial function is associated with future cognitive impairment and mobility decline, but the biological underpinnings for these associations are unclear. We examined metabolomic markers underlying skeletal muscle mitochondrial function, cognition and motor function.

METHODS

We analysed data from 560 participants from the Baltimore Longitudinal Study of Aging (mean age: 68.4 years, 56% women, 28% Black) who had data on skeletal muscle oxidative capacity (post-exercise recovery rate of phosphocreatine, kPCr) via 31P magnetic resonance spectroscopy and targeted plasma metabolomics using LASSO model. We then examined which kPCr-related markers were also associated with cognition and motor function in a larger sample (n = 918, mean age: 69.4, 55% women, 27% Black).

RESULTS

The LASSO model revealed 24 metabolites significantly predicting kPCr, with the top 5 being asymmetric dimethylarginine, lactic acid, lysophosphatidylcholine a C18:1, indoleacetic acid and triacylglyceride (17:1_34:3), also significant in multivariable linear regression. The kPCr metabolite score was associated with cognitive or motor function, with 2.5-minute usual gait speed showing the strongest association (r = 0.182). Five lipids (lysophosphatidylcholine a C18:1, phosphatidylcholine ae C42:3, cholesteryl ester 18:1, sphingomyelin C26:0, octadecenoic acid) and 2 amino acids (leucine, cystine) were associated with both cognitive and motor function measures.

CONCLUSION

Our findings add evidence to the hypothesis that mitochondrial function is implicated in the pathogenesis of cognitive and physical decline with aging and suggest that targeting specific metabolites may prevent cognitive and mobility decline through their effects on mitochondria. Future omics studies are warranted to confirm these findings and explore mechanisms underlying mitochondrial dysfunction in aging phenotypes.

The mediation roles of intermuscular fat and inflammation in muscle mitochondrial associations with cognition and mobility

BACKGROUND

Mitochondrial dysfunction may contribute to brain and muscle health through inflammation or fat infiltration in the muscle, both of which are associated with cognitive function and mobility. We aimed to examine the association between skeletal muscle mitochondrial function and cognitive and mobility outcomes and tested the mediation effect of inflammation or fat infiltration.

METHODS

We analysed data from 596 Baltimore Longitudinal Study of Aging participants who had concurrent data on skeletal muscle oxidative capacity and cognitive and mobility measures of interest (mean age: 66.1, 55% women, 24% Black). Skeletal muscle oxidative capacity was assessed as post-exercise recovery rate (kPCr) via P31 MR spectroscopy. Fat infiltration was measured as intermuscular fat (IMF) via CT scan and was available for 541 participants. Inflammation markers [IL-6, C-reactive protein (CRP), total white blood cell (WBC), neutrophil count, erythrocyte sedimentation rate (ESR), or albumin] were available in 594 participants. We examined the association of kPCr and cognitive and mobility measures using linear regression and tested the mediation effect of IMF or inflammation using the mediation package in R. Models were adjusted for demographics and PCr depletion.

RESULTS

kPCr and IMF were both significantly associated with specific cognitive domains (DSST, TMA-A, and pegboard dominant hand performance) and mobility (usual gait speed, HABCPPB, 400 m walk time) (all P < 0.05). IMF significantly mediated the relationship between kPCr and these cognitive and mobility measures (all P < 0.05, proportion mediated 13.1% to 27%). Total WBC, neutrophil count, and ESR, but not IL-6 or CRP, also mediated at least one of the cognitive and mobility outcomes (all P < 0.05, proportion mediated 9.4% to 15.3%).

CONCLUSIONS

Skeletal muscle mitochondrial function is associated with cognitive performance involving psychomotor speed. Muscle fat infiltration and specific inflammation markers mediate the relationship between muscle mitochondrial function and cognitive and mobility outcomes. Future studies are needed to confirm these associations longitudinally and to understand their mechanistic underpinnings.

Association between migraine and mitochondria: A Mendelian randomization study

BACKGROUND AND OBJECTIVE

Mitochondria are important organelles functioning in metabolic processes, inflammatory response and neurological disorders. Migraines are chronic and paroxysmal neurological disorders characterized by recurrent episodes of severe headache and other neurological symptoms. We explored whether mitochondria may be genetically and/or causally associated with migraine.

METHODS

Summary-level statistics of mitochondrial DNA copy number (mtDNA-CN), 69 mitochondria related exposures and migraine with aura, migraine without aura, migraine with aura and triptan purchases, migraine with aura, drug-induced, migraine without aura and triptan purchases and migraine without aura, drug-induced, were collected from genome-wide association studies (GWAS). The analysis employed two-sample Mendelian randomization, utilizing various methods including MR-Egger, inverse-variance weighted (IVW), MR-PRESSO (MR-pleiotropy residual sum and outlier), maximum likelihood, and weighted median.

RESULTS

We observed a potential association with decreased levels of mtDNA-CN with the risk of migraine without aura (Odds ratio (OR) 1.517, 95% Confidence interval (CI) 1.072-2.147, p = 0.019). Besides, for every 1 unit in NAD-dependent protein deacylase sirtuin-5 (SIRT5), relative risk of migraine without aura increased by 16.4%. For every 1 unit increase in Phenylalanine-transfer RNA (tRNA) ligase, relative risk of migraine without aura increased by 13.5%. For every 1 unit increase in Apoptosis-inducing factor 1, relative risk of migraine without aura increased by 27.4%.

CONCLUSION

This study indicates fresh evidence of association between mtDNA-CN, mitochondrial related exposures and migraine especially migraine without aura. The findings may shed light on developing interventions targeting on the causal pathway from mitochondria to migraine.