Older adults with depression tend to have smaller volumes of a specific part of the hippocampus brain region

A study involving over 2,000 cognitively healthy older adults reveals that individuals dealing with depression tend to have a smaller volume in a specific region of the hippocampus. This brain area, crucial for memory, is one of the first regions to be affected by Alzheimer's disease. Despite previous inconsistent findings, this research indicates that depression may play a role in altering the structure of the hippocampus.

The exact mechanisms remain unclear, as antidepressant medications could either protect against hippocampal shrinkage or conversely, contribute to it, depending on various factors such as the severity of depression and the presence of Alzheimer's-related proteins like amyloid and tau. Participants with depression were found to have reduced volumes in the CA23DG region of the hippocampus, but not in the CA1 or subiculum.

This finding remained consistent even after accounting for factors like body mass index, physical activity, tau levels, and the APOE4 gene variant, which is linked to increased Alzheimer's risk. Interestingly, depression severity and the onset age of depression did not correlate with hippocampal volume. However, when antidepressant use was considered, the link between depression and smaller hippocampal volumes weakened but antidepressants remained associated with reduced hippocampal size.

The researchers suggest that this association might be due to indication bias, where individuals with more severe depression are more likely to receive medication. The study emphasizes the importance of investigating the interplay between depression, antidepressant use, and hippocampal health, particularly in the context of Alzheimer's disease, to inform preventive strategies against brain atrophy and dementia.