New UK research has found that individuals who experience episodes of depression in their 20s, 30s and 40s are more likely to suffer from a worsening memory in their 50s.
Carried out by psychologists at the University of Sussex, the longitudinal study looked at data on more than 6,000 people taking part in the National Child Development Study, which was established in 1958 and followed participants from birth into childhood and through to adulthood.
The researchers measured symptoms of depression at ages 23, 33, 42 and 50, and memory, verbal fluency, information processing speed and accuracy at age 50.
The findings, published in the British Journal of Psychiatry, showed that one episode of depression or anxiety in early to mid-adulthood had little effect on the memory function of adults at age 50, regardless of which age the episode was experienced.
However, once the number of episodes increased to two or three over the three decades, the researchers found that there was a steady decrease in the participant's memory function at age 50.
The researchers say the link between depression and memory loss suggests that depressive symptoms experienced in early adulthood could predict dementia later in life.
However, episodes of depression and anxiety appeared to have little impact on verbal fluency, information processing speed, and accuracy.
The study is the first of its kind to investigate the possible relationship between depressive symptoms experienced across three decades of early to mid-adulthood and a decline in cognitive function in midlife, with the researchers noting that the findings highlight the importance of promoting mental health interventions among young adults.
"We found that the more episodes of depression people experience in their adulthood, the higher risk of cognitive impairment they have later in life. This finding highlights the importance of effective management of depression to prevent the development of recurrent mental health problems with long-term negative outcomes," said study author Dr. Darya Gaysina.
Co-author Amber John also added that, "We knew from previous research that depressive symptoms experienced in mid-adulthood to late adulthood can predict a decline in brain function in later life but we were surprised to see just how clearly persistent depressive symptoms across three decades of adulthood are an important predictor of poorer memory function in mid-life."
"From an individual's perspective, this research should be a wake-up call to do what you can to protect your mental health, such as maintaining strong relationships with friends and family, taking up physical exercise or practicing mindfulness meditation -- all of which have been shown to boost mental health. Then of course, seeing your GP for advice if you feel you need help with depression or anxiety."