Late-Life Depression Linked to Higher Alzheimer’s Risk

German scientists are suggesting that patients with late-life depression could be at increased risk of developing Alzheimer’s disease faster than their non-depressed peers. They presented the new research earlier this month at the 2014 Meeting of the Society of Nuclear Medicine and Molecular Imaging in St. Louis, Missouri.

“There is a relationship between depressive symptoms and a higher amyloid load in the brains of mild cognitively impaired patients and consecutive progression to Alzheimer’s dementia,” says the study’s principal scientist Axel Rominger, MD, associate professor and vice chair of the Department of Nuclear Medicine at the University of Munich in Germany.
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Using the Alzheimer’s Disease Neuroimaging Initiative database, Rominger and his team looked at 371 patients with mild cognitive impairment who underwent positron emission tomography (PET) imaging with the radiotracer F-18 florbetapir and magnetic resonance imaging. Their results showed that mild cognitively impaired patients with depressive symptoms had higher amyloid deposition than non-depressed controls.

High levels of beta-amyloid, a naturally occurring protein in the brain, are a hallmark of Alzheimer’s disease. The researchers found a combination of elevated amyloid levels and coexisting depressive symptoms put patients at risk for faster progression to Alzheimer’s disease.

“The key finding of this research was that mild cognitively impaired patients with a high amyloid load in their brain can be separated in two subcollectives with different time to progression to Alzheimer’s dementia,” Rominger says. “One group without depressive symptoms and a group with depressive symptoms—the latter one with the fastest progression to dementia.”

The researchers did not identify the reason for this connection as their study was not targeted to elucidate pathophysiologic mechanisms of the interaction between depressive symptoms and progression from mild cognitive impairment to Alzheimer’s.

However, they do believe that knowing more about contributing risk factors for Alzhimer’s disease could potentially help patients and their families make necessary lifestyle changes and preparations sooner.

“Mild cognitively impaired patients should be monitored for the development of depressive symptoms,” Rominger says.  While he and his colleagues cannot provide recommendations on treating these symptoms more aggressively, they believe future studies should be developed to look at specific interventions that may benefit this patient population. 

In the future, Rominger says he plans to investigate the effect of antidepressants (e.g. SSRI) on the amyloid load using PET imaging, given the accumulating evidence that SSRIs inhibit amyloid production.

—Colleen Mullarkey

Reference

Brendel M, Kalinowski E, Delker A, Bartenstein P, Rominger A. Subsyndromal late life depression is associated with amyloid accumulation in mild cognitive impairment. Presented at: Society of Nuclear Medicine and Molecular Imaging 61th Annual Meeting, St. Louis, Missouri. June 8, 2014.