Depressive Symptoms May Hasten Memory Decline in Older People

A new study led by researchers at UCL and Brighton and Sussex Medical School has found that depressive symptoms and memory decline are closely interrelated in older adults, each potentially exacerbating the other. Published in JAMA Network Open, the study analyzed 16 years of longitudinal data from 8,268 adults in England, averaging 64 years of age. The researchers concluded that depressive symptoms often precede memory decline, and conversely, memory decline can lead to an increase in depressive symptoms.

Dr. Dorina Cadar, senior author from UCL and Brighton and Sussex Medical School, highlighted the bidirectional relationship between depression and memory impairment, suggesting that interventions aimed at reducing depressive symptoms might help slow memory decline. Jiamin Yin, the lead author and a doctoral student at the University of Rochester, emphasized the importance of monitoring memory changes in older adults with depressive symptoms to prevent further cognitive decline and addressing depressive symptoms in those with memory impairment to protect against the development of depression.

The researchers proposed several mechanisms by which depression might affect memory. These include neurochemical imbalances such as reduced levels of serotonin and dopamine, structural changes in brain regions involved in memory processing, and disruptions to the brain’s ability to reorganize and form new connections. Psychological factors like rumination, or repetitive negative thinking, may also contribute to memory impairments.

Conversely, memory lapses can lead to frustration, loss of confidence, and feelings of incompetence, which are common triggers for depressive episodes. Memory impairments can disrupt daily functioning and social interactions, potentially leading to social isolation and subsequent depressive symptoms.

Dr. Cadar noted that depression could cause structural changes in the brain, such as in the hippocampus, which is critical for memory formation and retrieval. Chronic stress and high cortisol levels associated with depression can damage neurons in these areas. Understanding these mechanisms is crucial for developing targeted interventions to improve mood and slow cognitive decline in individuals with depression and memory impairment.

The study utilized data from the English Longitudinal Study of Ageing (ELSA), which surveys a nationally representative population sample in England every two years. Findings indicated that participants with higher initial depressive symptoms were more likely to experience faster memory decline, while those with poorer initial memory were more likely to see an increase in depressive symptoms over time. Additionally, participants who experienced an increase in depressive symptoms during the study tended to have a steeper memory decline, and vice versa. However, this bidirectional pattern was not observed with verbal fluency.

The researchers controlled for factors such as physical activity and life-limiting illnesses, acknowledging that the observational nature of the study does 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.

Story Source: Materials provided by University College London. Note: Content may be edited for style and length.