Here is one of many studies to show some correlation between longer telomeres and slower accumulation of age-related damage. Questions remain as to where telomere length fits into aging: is it more of a cause or more of a marker of other processes? From the abstract: "Telomere shortening is a marker of cellular aging and has been associated with risk of Alzheimer's disease. Few studies have determined if telomere length is associated with cognitive decline in non-demented elders. We prospectively studied 2734 non-demented elders (mean age: 74 years). We measured cognition with the Modified Mini-Mental State Exam (3MS) and Digit Symbol Substitution Test (DSST) repeatedly over 7 years. Baseline telomere length was measured in blood leukocytes and classified by tertile as 'short', 'medium', or 'long'. At baseline, longer telomere length was associated with better DSST score (36.4, 34.9 and 34.4 points for long, medium and short) but not for change in score. However, 7-year 3MS change scores were less among those with longer telomere length. ... Findings were similar after multivariable adjustment for age, gender, race, education, assay batch, and baseline score. ... Thus, telomere length may serve as a biomarker for cognitive aging."