Happiness during young adulthood can protect against dementia later on

SAN FRANCISCO, Calif. — Does your mental health in your 20s determine your risk of dementia decades later? A new study finds happiness during young adulthood may be the best medicine for your brain during old age. Researchers from the University of California-San Francisco have discovered a link between depression at younger ages and cognitive decline as those people reach their senior years.

The team found that having poor mental health and experiencing depressive symptoms in early adulthood can lead to worse cognition 10 years later and full-on cognitive decline during old age.

Researchers used a statistical model to predict the average path of depressive symptoms among a group of 15,000 participants between 20 and 89 years-old. Study authors broke this group up into three categories: older, midlife, and young adulthood.

After applying this mental health pathway to the 6,000 older participants in the study, the study reveals a 73-percent higher chance of cognitive impairment among those with more depressive symptoms during young adulthood. The team also found a 43-percent higher chance of mental decline in those experiencing depression later in life.

Researchers accounted for possibly influential factors like age, sex, race, education, body mass index, history of diabetes, and smoking habits. Although depression during midlife appeared to have a link to cognitive impairment, the team discounted these particular results after adjusting for depression during other stages of life.

Stress may damage memory ability

For those experiencing depression, stress and anxiety often contribute to their poor mental health as well. Study authors say this also factors into the brain’s ability to properly store and hold onto memories — a common side-effect of dementia.

“Several mechanisms explain how depression might increase dementia risk,” says first author Willa Brenowitz, PhD, MPH, from the UCSF Department of Psychiatry and Behavioral Sciences and the UCSF Weill Institute for Neurosciences, in a university release.

“Among them is that hyperactivity of the central stress response system increases production of the stress hormones glucocorticoids, leading to damage of the hippocampus, the part of the brain essential for forming, organizing and storing new memories.”

Previous studies have also found a link between a decaying hippocampus and depression, with one study showing that women suffer faster rates of brain volume loss than men.

Risk of depression only increases as we age

Study authors used a 10-item questionnaire to assess each participant’s level of depression over the last week. The team found moderate to high depressive symptoms in 13 percent of young adults, 26 percent of middle-aged adults, and 34 percent of older adults. Nearly 1,300 participants were also diagnosed with cognitive impairment after taking a neuropsychological test.

“Generally, we found that the greater the depressive symptoms, the lower the cognition and the faster the rates of decline,” adds Brenowitz. “Older adults estimated to have moderate or high depressive symptoms in early adulthood were found to experience a drop in cognition over 10 years.”

Senior author Kristine Yaffe, MD notes that around 20 percent of the population suffers from depression at some point in their lifetime. With that in mind, the team says it’s important to recognize mental health’s role in brain health as we age.

The findings appear in the Journal of Alzheimer’s Disease.

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