Depressive symptoms are associated with subsequent memory decline in older adults, while poorer memory is also linked to an increase in depressive symptoms later on, according to a new study led by researchers at UCL and Brighton and Sussex Medical School.

The study, published in JAMA Network Open, analyzed 16 years of longitudinal data from 8,268 adults in England, with an average age of 64.

The researchers found that depression and memory are closely interrelated, with both appearing to influence each other.

Senior author Dr. Dorina Cadar, from the UCL Department of Behavioural Science & Health and Brighton and Sussex Medical School, stated: “Depression and poor memory often occur together in older people, but the causal direction has been unclear. Our study shows that the relationship is bidirectional, with depressive symptoms preceding memory decline and memory decline linked to subsequent depressive symptoms. This suggests that interventions to reduce depressive symptoms may help to slow down memory decline.”

Lead author Jiamin Yin, who graduated from UCL and is now a doctoral student at the University of Rochester, New York, 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. Conversely, it is also critical to address depressive symptoms in those with memory decline to protect them from developing depression and memory dysfunction.”

The research team suggested that depression might affect memory due to changes in the brain associated with depression. These include neurochemical imbalances, structural changes in memory-related regions, and disruptions in the brain’s ability to reorganize and form new connections. Psychological factors, such as rumination, may also contribute to memory impairments. On the other hand, memory lapses can lead to frustration, loss of confidence, and feelings of incompetence, which can trigger depressive episodes. Memory impairment may also disrupt daily functioning and social interactions, leading to social isolation and potentially triggering depressive symptoms.

Dr. Cadar added: “Depression can cause changes in brain structures, such as the hippocampus, critical for memory formation and retrieval. Chronic stress and high levels of cortisol associated with depression can damage neurons in these areas. However, further understanding the mechanisms linking memory decline and depression is crucial for developing targeted interventions aimed at improving mood and slowing cognitive decline in individuals with depression and memory impairment.”

For this study, the researchers analyzed data from the English Longitudinal Study of Ageing (ELSA), where a nationally representative sample in England answers a wide range of questions every two years.

People with higher initial depressive symptoms were more likely to experience faster memory decline later, while those with poorer initial memory were more likely to experience an increase in depressive symptoms later. Participants who experienced a greater increase in depressive symptoms during the study were more likely to have a steeper memory decline, and vice versa.

The study found no such pattern for verbal fluency. While less verbal fluency was linked to more depressive symptoms at the start, changes in one did not predict later changes in the other.

The researchers accounted for factors such as physical activity and life-limiting illness. As an observational study, it could not establish causality.

The study received support from the National Institute on Aging, the Economic and Social Research Council (ESRC), the National Institute for Health and Research (NIHR), Alzheimer’s Society UK, and Alzheimer’s Research UK.

 

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