One of the most powerful predictors in neuropsychiatry is the epsilon 4 (ε4) allele of the apolipoprotein gene (APOE).

Individuals who carry this ε4 variant of APOE are at increased risk for developing Alzheimer’s disease, early age of Alzheimer’s disease onset, and more rapid progression of Alzheimer’s disease symptoms. APOE ε4 has also been associated with atherosclerosis as well as cardiovascular and cerebrovascular disease.

A new study published in the current issue of Biological Psychiatry suggests that even when controlling for the risk for Alzheimer’s disease, the APOE ε4 allele also conveys an increased risk for late-life depression.

In this study, researchers examined the relationship between APOE ε4 and depression in a large population-based sample of 839 older Swedish adults followed over 5 years.

“In our study, the presence of the APOE ε4 predicted future depression, even after excluding individuals who later developed dementia,” explained corresponding author Dr. Silke Kern at the University of Gothenburg. “It was also related to dementia. APOE ε4 might be a marker for identifying older persons at risk to develop depression or dementia, which could be important for prevention and early detection of these common disorders.”

“Late-life depression is an under-appreciated source of distress and disability in older people,” said Dr. John Krystal, Editor of Biological Psychiatry. “The current study suggests a new link to the biology of Alzheimer’s disease, even among people who do not show signs of memory impairment.”