Objective: Psychological factors such as the stress of caregiving are emerging as predictors of telomere length, an index of biological aging. However, although lifetime major depressive disorder is associated with shorter telomeres, less is known about depressive symptoms. Depression and depressive symptoms are associated with a range of morbidities and mortality, but the extent to which they predict biological aging is unclear. The present study examined participants in the West of Scotland Twenty-07 Study across three age cohorts and four waves of data collection from 1992/1993 to 2007/2008.
Methods: Participants were 37, 57, and 76 years old at final data collection. Depressive symptoms were measured using the Hospital Anxiety and Depression Scale at each time point. Telomere length was assessed from 1063 blood samples collected at the final wave in 2007/2008 for respondents who also had depression data.
Results: Average depression symptoms (β= -.12, p = .047) and their change over time (β = -.12, p = .031) were negatively associated with telomere length, but only in the youngest cohort. Depressive symptoms were not cross sectionally associated with telomere length in 2007 to 2008 (β= -.03, p = .45). In the youngest cohort only, depressive symptoms assessed in 1995 to 1997 and 2000 to 2004 were associated with shorter telomere length (β = .14 [p = .046] and β = .18 [p = .012], respectively), but not 1992 to 1993 or 2007 to 2008; associations in the middle- and older-aged cohorts were nonsignificant.
Conclusions: Depressive symptoms are longitudinally associated with shorter telomere length, but only in younger adults.