Telomere Length, Uncommon Genetic Variation, and Depression

Previous research attempting to better understand the genetic basis of depression has demonstrated few clear findings. The present study employed a cross-sectional design to analyze the association between leukocyte telomere length and depression in 2,710 participants from the Dallas Heart Study (DHS), as well as the potentially moderating influence of ethnicity/race, APOE allele variation, and average self-reported hours of sleep per night. Furthermore, in an exploratory exome-wide association study, we analyzed associations between a subset of 2,949 participants from the DHS with depression data available and 247,870 genetic variants. Scores from the primary measure of depression--The Quick Inventory of Depressive Symptomatology (QIDS)--showed a significant negative association with telomere length but only in the Caucasian subset of the sample. Scores from the secondary measure of depression--The DHS's "felt depressed" question--showed a significant negative association with telomere length across the whole sample, as well as in the African American subset, but not within the Caucasian or Hispanic subsets. Neither APOE allele variation nor average nightly sleep was a significant moderator of the association between depression and telomere length. No significant associations between depressions scores and specific genetic variants were found in the exome-wide association study. These finding help clarify the relationship between depression and telomere length by highlighting the importance of ethnicity/race in the relationship between depression and telomere length. Future research involving depression and telomere length should account for ethnicity/race in their analyses, while future exome-wide association studies of depression should seek more severe and well-defined cases of depression.