Depressive symptoms may speed up memory decline in older people, a new study has found.
Poorer memory was also linked to an increase in depressive symptoms, suggesting that depression and memory were closely interrelated, with both seeming to affect the other.
The findings, published in JAMA Network Open, suggest that interventions to reduce depressive symptoms may help to slow down memory loss.
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Researchers led by scientists at University College London (UCL) and Brighton and Sussex Medical School examined data from 8,268 adults in England. The data was part of the English Longitudinal Study of Ageing (ELSA), in which a nationally representative population sample in England answers a wide range of questions every two years. The average age of those studied was 64, and the data was collected over 16 years between 2002/2003 and 2017/20018.
The findings show that people who had a greater level of depressive symptoms at the start of the study, followed by an accelerated change in depressive symptoms over time, experienced faster memory decline. Conversely, people who experienced a steeper decline in memory over the period of study were also more likely to have a sharper increase in depressive symptoms.
The researchers also looked at verbal fluency over time and found that although less verbal fluency was linked to more depressive symptoms at the start of the study, changes in one did not predict later changes in the other.
Senior author Dr Dorina Cadar of the UCL Department of Behavioural Science & Health and Brighton and Sussex Medical School said: ‘It is known that depression and poor memory often occur together in older people, but what comes first has been unclear.’
She added: ‘Our study shows that the relationship between depression and poor memory cuts both ways, with depressive symptoms preceding memory decline and memory decline linked to subsequent depressive symptoms.’
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The researchers suggest that depression may cause changes in the brain, which could affect memory. These include changes in neurochemicals such as serotonin and dopamine, structural changes in regions involved in memory processing, and disruptions to the brain’s ability to re-organise and form new connections.
In addition, the researchers say that memory impairments could occur as a result of depressive symptoms. Psychological factors such as repetitive thinking or dwelling on negative feelings may increase the rate of memory loss. Memory loss in itself can lead to feelings of isolation and frustration, which can also increase the likelihood of depressive episodes.
Lead author Jiamin Yin, who graduated from UCL, said: ‘These findings underscore the importance of monitoring memory changes in older adults with increasing depressive symptoms to identify memory loss early and prevent further worsening of depressive function.’
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She added: ‘Conversely, it is also critical to address depressive symptoms among those with memory decline to protect them from developing depression and memory dysfunction.’
