A large longitudinal study carried out by the University of Sussex found a clear link between episodes of depression and anxiety experienced by adults in their twenties, thirties and forties, with a decrease in memory function by the time they are in their fifties.
The study is the first of its kind to look at the relationship between depressive symptoms experienced across three decades of early-mid adulthood and a decline in cognitive function in midlife.
The Sussex psychologists analysed data from the National Child Development Study, which was established in 1958 with a cohort of over 18,000 babies and followed participants from birth into childhood and through to adulthood. The Sussex psychologists found that an accumulation of symptoms experienced by participants over the three decades provided a strong indicator of a linear decrease in memory function by the time the adults were fifty.
They found that one episode of depression or anxiety had little effect on the memory function of adults in midlife, regardless of which decade it was experienced, but that once the episodes increased to two or three over the course of the three decades, that this predicted a steady decrease in the participant’s memory function by the time they reached fifty.
This, the psychologists from the EDGE Lab at the University of Sussex argue, highlights an opportunity to protect future memory function by promoting mental health interventions amongst young adults and they are calling on the UK government to invest in the mental health of young adults as a preventative measure to protect the future brain health of our ageing population.
Dr Darya Gaysina, senior lecturer in psychology at the University of Sussex, said: “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.
“We’d therefore like to see the government investing more in the mental health provision for young adults, not only for the immediate benefit of the patients, but also to help protect their future brain health.”
As well as memory, the psychologists also assessed verbal fluency, information processing speed and accuracy scores of the participants once they turned fifty.
Encouragingly, episodes of depression and anxiety had little impact on the latter four areas of cognitive function but the associated loss of memory suggests that depressive symptoms experienced in early adulthood could predict dementia in older adulthood.
Previous research carried out by the EDGE Lab at the University of Sussex had found a relationship between depressive symptoms experienced in older adulthood and a faster rate of cognitive decline, but this is the first time that such a large and UK nationally representative sample has been able to make this link in the first three decade of adulthood.
University of Sussex psychology PhD student Amber John said: “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.
“With the publication of this research, we’re calling for the government to invest in mental health provision to help stem the risk of repeated episodes of depression and anxiety.
“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 practising 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.”
Background: Affective disorders are associated with poorer cognition in older adults; however, whether this association can already be observed in mid-life remains unclear.
Aims: To investigate the effects of affective symptoms over a period of 30 years on mid-life cognitive function. First, we explored whether timing (sensitive period) or persistence (accumulation) of affective symptoms predicted cognitive function. Second, we tested how different longitudinal trajectories of affective symptoms were associated with cognitive function.
Method: The study used data from the National Child Development Study. Memory, verbal fluency, information processing speed and accuracy were measured at age 50. Affective symptoms were measured at ages 23, 33, 42 and 50 and used to derive longitudinal trajectories. A structured modelling approach compared a set of nested models in order to test accumulation versus sensitive period hypotheses. Linear regressions and structural equation modelling were used to test for longitudinal associations of affective symptoms with cognitive function.
Results: Accumulation of affective symptoms was found to be the best fit for the data, with persistent affective symptoms being associated with poorer immediate memory (b = −0.07, s.e. = 0.03, P = 0.01), delayed memory (b = −0.13, s.e. = 0.04, P < 0.001) and information processing accuracy (b = 0.18, s.e. = 0.08, P = 0.03), but not with information processing speed (b = 3.15, s.e. = 1.89, P = 0.10). Longitudinal trajectories of repeated affective symptoms were associated with poorer memory, verbal fluency and information processing accuracy.
Conclusions: Persistent affective symptoms can affect cognitive function in mid-life. Effective management of affective disorders to prevent recurrence may reduce risk of poor cognitive outcomes and promote healthy cognitive ageing.
Amber John, Sarah-Naomi James, Urvisha Patel, Jennifer Rusted, Marcus Richards, Darya Gaysina