Researchers explore the link between tau levels and depressive symptoms in older people

During typical aging and Alzheimer's disease progression, higher levels of a protein called tau are associated with more depressive symptoms. New in JNeurosci, Teodora Markova, from Brandeis University, and colleagues explored the relationship between tau levels and depressive symptoms in older people with and without cognitive (memory, attention, and thinking) deficits that characterize Alzheimer's disease. 

The researchers assessed data collected by the Alzheimer's Disease Neuroimaging Initiative from elderly men and women with and without cognitive issues. Participants had completed several tau-detecting imaging scans and questionnaires measuring depressive symptoms across multiple visits. Over time, the speed of tau buildup in participants regulated how quickly depressive symptoms rose in individuals with cognitive skills intact. Furthermore, in cognitively intact people, increased tau levels could predict higher scores in the depression test. These findings suggested to the researchers that tau accumulation precedes and likely contributes to more depressive symptoms. Notably, none of these observations were found in individuals with Alzheimer's or even mild cognitive impairment. 

According to the research team, this work shows that early increases in tau levels during aging may contribute to the rise of depressive symptoms. The researchers suggest that monitoring depressive trajectories in aging populations could complement other measures to help assess risk for neurodegenerative disease.

Future work can continue to track how participants' tau levels and depression symptoms evolve over longer periods of time, particularly as some develop cognitive impairment or more clinically significant levels of depression. Continuing to follow these trajectories, observing how early mood changes relate to later clinical outcomes, and establishing relationships with other methods tracking the development of Alzheimer's disease will provide more clarity on methods to determine which individuals may be at an increased risk."

Teodora Markova, Brandeis University