Depressive symptoms that occur in both midlife and late life are associated with an increased risk of developing vascular dementia, while symptoms that occur in late life only are more likely to be early signs of Alzheimer’s disease, according to a study led by Deborah Barnes, PhD, a mental health researcher at the San Francisco VA Medical Center.
The study, which appears in the May issue of the Archives of General Psychiatry, is the first to examine whether midlife or late life depression is more likely to lead to either Alzheimer’s disease or vascular dementia in the long term. The researchers explained that vascular dementia, the second most common type of dementia, develops when impaired blood flow to parts of the brain deprives cells of nutrients and oxygen.
“People who had depressive symptoms in both midlife and late life were much more likely to develop vascular dementia, while those who had depressive symptoms in late life only were more likely to develop Alzheimer’s disease,” said Dr. Barnes, who is also an associate professor of psychiatry at the University of California, San Francisco.
UCSF and Kaiser Permanente investigators examined the association between depressive symptoms and dementia over the course of 45 years in a longitudinal study of more than 13,000 long-term members of the Kaiser Permanente Northern California integrated care delivery system. The study population consisted of members who participated in a voluntary health examination called the Multiphasic Health Checkup in San Francisco and Oakland during the period from 1964 to 1973 when they were 40-55 years old.
Participants were evaluated for depressive symptoms in midlife as part of the Multiphasic Health Checkup and again in late life between 1994 and 2000. Between 2003 and 2009, 3,129 participants were diagnosed with dementia.
“The findings have important public health implications because they raise hope that adequate treatment of depression in midlife may reduce dementia risk, particularly vascular dementia, later in life,” said Rachel Whitmer, PhD, a research scientist at the Kaiser Permanente Northern California Division of Research and the principal investigator of the study.