The authors point out that they used meditational analysis and that a causal effect should be interpreted cautiously because unmeasured factors such as diet could co-vary with hippocampal volume and account for the mediation. They suggest that future studies use longitudinal designs, clinical populations, and other measuring techniques to validate the finding. 5B. Telomeres Telomere length animal study is a marker of cellular aging and has been associated with dementia . A report  involving 2,401 twins found that leukocyte telomere length was 200 nucleotides longer in those most active compared with those least active. Twins discordant for exercise amount showed that twins doing more exercise had longer telomeres. Another study  showed that leukocyte telomere length was longer in duration trained individuals, with VO2peak explaining 60% of the variance.
The Health ABC study  reported that telomere length may serve as a biomarker of cognitive aging. The investigators noted that baseline telomere length was associated with digit symbol scores (36.4, 34.9, and 34.4 points for long, medium, and short, respectively; P < 0.01). The 7-year Modified Mini-Mental Status Examination change scores were lower among those with longer telomere length (-1.7 versus -2.5 and -2.9 points; P = 0.01). The investigators concluded that telomere length may serve as a biomarker for cognitive aging. There is a clear need for a prospective controlled study evaluating the effect of exercise on telomere length. 5C. Plasma A?? Exercise is known to decrease inflammatory markers  and improve insulin sensitivity [57,58].
This is important because Cotman and colleagues  have postulated that the common mechanism whereby exercise improves brain health is through decreasing inflammation. We hypothesize that both A??40 and A??42 will decrease with exercise. Interestingly, a nonsignificant trend toward a decline in plasma A??42 Carfilzomib was observed selleck chemical in a small, MCI exercise study . 5D. Cerebrospinal fluid A??42 and Pittsburgh compound-B scanning Liang and colleagues  reported a study of 69 older adults who had PIB and CSF measures of A??42 and tau. The authors administered an exercise questionnaire estimating the amount of exercise performed in the previous 10 years. They found that those with increased PIB and tau had significantly lower exercise scores. The PIB association remained significant after adjustment for covariates. Those doing 7.5 metabolic equivalent task (MET) hours/week (which is equal to 30 minutes five times per week) had significantly lower PIB (P = 0.