Associations of mitochondrial genomic variation with successful neurological aging.

Mitochondrial health is an integral factor in aging, with mitochondrial dysfunction known to increase with age and contribute to the development of age-related neurodegenerative disorders. Additionally, the mitochondrial genome (mtDNA) has been shown to acquire potentially damaging somatic variation as part of the aging process, while mtDNA single nucleotide polymorphism (SNPs) have been shown to be both protective and detrimental for various neurodegenerative diseases. Yet, little is known about the involvement of mtDNA variation in longevity and successful neurological aging. In this study, we examined the association of mtDNA SNPs, in the form of mitochondrial haplogroups, with successful neurological aging in 1,405 unrelated neurologically healthy subjects. Although not quite significant after correcting for multiple testing (P < 0.0017 considered as significant), we detected a nominally significant association between the I haplogroup (N = 45, 3.2 %) and a younger age (ß: -5.00, P = 0.006), indicating that this haplogroup is observed less frequently in older neurologically healthy individuals and may be associated with decreased survival. Replication of this finding in independent neurologically healthy cohorts will be imperative for shaping our understanding of the biological processes underlying healthy neurological aging.

CLEC3B p.S106G Mutant in a Caucasian Population of Successful Neurological Aging.

A number of efforts are underway to better understand the role of genetic variation in successful aging and longevity. However, to date, only two genes have been consistently associated with longevity in humans: APOE and FOXO3, with the APOE ɛ2 allele also protective against dementia. Recently, using an exome-wide SNP array approach, a missense variant CLEC3B c.316G>A (rs13963 p.S106G) was reported to associate with longevity in two independent cohorts of Japanese and Chinese participants. Interestingly, CLEC3B p.S106G is more frequent in Caucasian populations. Herein, we examined the frequency of CLEC3B p.S106G in a Caucasian series of 1,483 neurologically healthy individuals with a specific subset >80 years of age. Although our findings do not support an association between CLEC3B p.S106G and aging without neurological disease (p = .89), we confirmed the association between the APOE ε2 allele and better survival without neurological disease (p = .001). Further assessment of healthy aged cohorts that retain intact neurological function will be critical to understand the etiology of neurodegenerative disease and the role of age at risk.

Behavioral Interventions to Prevent or Delay Dementia: Protocol for a Randomized Comparative Effectiveness Study.

BACKGROUND: Currently, people at risk for dementia and their caregivers are confronted with confusing choices about what behavioral interventions are most effective. OBJECTIVE: The objective of this study is to determine which empirically supported behavioral interventions most impact the outcomes highly valued by patients with mild cognitive impairment and their partners. METHODS: This protocol describes a comparative effectiveness trial targeting 300 participants with mild cognitive impairment and their study partners. The trial is being conducted at the Mayo Clinic campuses in Arizona, Florida, Minnesota, and the University of Washington in Seattle. The study examines the contribution of five behavioral interventions (yoga, memory compensation training, computerized cognitive training, support groups, and wellness education) on primary outcomes of participant and partner quality of life and self-efficacy. In this unique 10-day multicomponent intervention, groups of couples were randomized to have one of the five interventions withheld while receiving the other four. Although the longitudinal follow-up is still under way, enrollment results are available and reported. RESULTS: In total, 272 couples have been enrolled in the trial and follow-up visits continue. Outcomes will be assessed at the end-of-intervention and 6-, 12-, and 18-month follow-ups. We anticipate reporting on our primary and secondary outcomes across time points in the next 2 years. CONCLUSIONS: This paper describes the protocol for a randomized comparative effectiveness study of behavioral interventions to prevent or delay dementia. We describe of the rationale, design, power analysis, and analysis plan. Also because enrollment is complete and we are in follow-up phases of the study, we have included enrollment data from the trial. TRIAL REGISTRATION:  ClinicalTrials.gov NCT02265757; http://clinicaltrials.gov/ctsshow/ NCT02265757 (Archived by WebCite at http://www.webcitation.org/6ueRfwSYv).