New Link Between Depression and Cognitive Decline in Older Adults

A hormone known as IGF-1 may serve as the link between depression and memory loss in older adults.

Depression and memory loss are linked through an insulin-like growth factor known as IGF-1, according to research published in the April 2014 issue of Psychoneuroendocrinology.

Previous studies have concluded IGF-1 is important for growth and memory preservation, especially in older adults, while other studies have found depression is a risk factor in memory loss for older adults. However, until now, scientists were unsure if memory loss could be slowed by fighting depression.

Researchers from the University of Rochester School of Medicine and Dentistry and the School of Nursing measured IGF-1 from blood samples taken from 94 healthy older adults. The participants’ depressive symptoms were assessed on the Geriatric Depression Scale, while learning and memory were assessed using the Rey Auditory Verbal Learning Test.

At first, Kathi L. Heffner, PhD, could not find consistent evidence among the data linking IGF-1 and memory. She then approached Feng Vankee Lin, PhD, RN, for her expertise in cognitive aging, who had the idea to examine depressive symptoms.

Once the researchers reexamined the data with a new lens, they found adults with lower cognitive ability were more likely to have depressive symptoms if they also demonstrated low levels of IGF-1. The opposite was also true, as adults with high levels of the hormone experienced no association between depressive symptoms and memory.

“IGF-1 is currently a hot topic in terms of how it can promote neuroplasticity and slow cognitive decline,” lead author Lin said in a press release. “Depression, memory, and the IGF-1 receptor are all located in a brain region which regulates a lot of complicated cognitive ability. As circulating IGF-1 can pass through the blood-brain barrier, it may work to influence the brain in a protective way.”

The research team has clinical trials underway to test whether IGF-1 is an effective therapeutic agent to slow or prevent cognitive decline in at-risk older adults.