Study: Intelligence predicts change in depressive symptoms in later life

People who experience cognitive decline in later life are at a higher risk of experiencing depression, according to new research.

The study in the journal Psychological Science examined fluid intelligence, a measure of a person’s adaptive reasoning and problem-solving skills.

“Most adults will experience some cognitive declines in later life, and we wanted to know whether this was predictive of increased depression risk. At the same time, we wanted to know whether age-related elevation in depression symptoms (for example, due to bereavement or illness) might adversely affect cognitive function,” said study author Stephen Aichele of the Universities of Lausanne and Geneva.

The researcher examined data from 1,091 participants of the longitudinal Lothian Birth Cohort 1936 study. The participants were given an intelligence test in 1947 at age 11 and were tested repeatedly at 3-year intervals between the ages of 70 and 79.

Overall, both fluid intelligence and depressive symptoms tended to worsen between ages 70 and 79 years. However, the researchers found that poorer fluid intelligence predicted subsequent increases in depressive symptoms. Heightened depressive symptoms, on the other hand, did not predict subsequent declines in fluid intelligence.

“Age-related decrements in reasoning ability precede multi-year increases in depressive symptoms. This implies that monitoring for cognitive decrements in later adulthood may expedite efforts to reduce associated increases in depression risk,” Aichele told PsyPost.

“The next step will be to look more closely at factors (such as training, treatment, and social support) that can mitigate the association between age-related worsening in cognitive function and increasing depression risk.”

The study, “Fluid Intelligence Predicts Change in Depressive Symptoms in Later Life: The Lothian Birth Cohort 1936,” was authored by Stephen Aichele, Paolo Ghisletta, Janie Corley, Alison Pattie, Adele M. Taylor, John M. Starr, and Ian J. Deary.