The relationship between cognitive ability and depression: a longitudinal data analysis

There is literature indicating cognitive ability and depression are related, but few studies have examined the direction of the relationship. This study examined the relationship between depression levels and cognitive abilities from adolescence to early adulthood. Using the National Longitudinal Study of Adolescent Health (n = 14,322), this study used path modeling to investigate the relationship between depression and cognitive ability at baseline and again 8 years later. After controlling for initial levels of depression, cognitive ability, and other covariates, depressive symptoms in adolescence are related to cognitive ability in early adulthood, but adolescent cognitive ability is not related to adult depression levels. Moreover, after controlling for adolescent levels of depression and cognitive ability, the cognitive ability-depression relationship disappears in adulthood. The cognitive ability-depression relationship appears early in life, and it is likely that the presence of depressive symptoms leads to lower cognitive ability. Thus, intervening at early signs of depression not only can help alleviate depression, but will likely have an effect of cognitive ability as well.