BACKGROUND: Depression has been cross-sectionally associated with short telomeres as a measure of biological age. However, the direction and nature of the association is currently unclear.

AIMS: We examined whether short telomere length is associated with depression cross-sectionally as well as prospectively and genetically.

METHOD: Telomere length and three polymorphisms, TERT, TERC and OBFC1, were measured in 67 306 individuals aged 20-100 years from the Danish general population and associated with register-based attendance at hospital for depression and purchase of antidepressant medication.

RESULTS: Attendance at hospital for depression was associated with short telomere length cross-sectionally, but not prospectively. Further, purchase of antidepressant medication was not associated with short telomere length cross-sectionally or prospectively. Mean follow-up was 7.6 years (range 0.0-21.5). The genetic analyses suggested that telomere length was not causally associated with attendance at hospital for depression or with purchase of antidepressant medication.

CONCLUSIONS: Short telomeres were not associated with depression in prospective or in causal, genetic analyses.