Depression Symptoms and Alzheimer's Risk

An important study was published today in Lancet Psychiatry. 

This study examined the role of depression symptoms in risk for later development of dementia including Alzheimer's disease.

Previous work on this topic has relied on cross-sectional risk factor design. However, the study published today used a prospective longitudinal design for elderly individuals participating the Rotterdam study.

Depressive symptoms were measured over time and compared to latter risk for development of dementia.

The key findings from the study included:

• Dementia emerged in 10% of the low depression score subjects during the course of the study
• Depressive symptoms over time could be classified into four types: low throughout, low at onset but increasing over course of study, high but remitting during the course of follow up and persistently high during the study period.
• Only the initial low depressive symptoms increasing over time was linked to a higher rate of dementia (22%) odds ratio of 1.4.

This finding has several implications. Late onset depression of increasing severity over time may indicate a prodromal phase for Alzheimer's and other dementias. Depression and dementia do share some features of pathophysiology including impaired neuroplasticity and markers of enhanced brain inflammation.

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Figure of frontal lobes highlighted is from an iPad screen shot from the app 3D Brain.

Mirza, S., Wolters, F., Swanson, S., Koudstaal, P., Hofman, A., Tiemeier, H., & Ikram, M. (2016). 10-year trajectories of depressive symptoms and risk of dementia: a population-based study The Lancet Psychiatry DOI: 10.1016/S2215-0366(16)00097-3