Experiencing depressive symptoms as a young adult and beyond may lead to worse thinking and memory skills in middle age, a study published Wednesday finds.
Every five years for 20 years, 3,117 participants were evaluated for depressive symptoms, completing a questionnaire about their appetite, sleep, ability to concentrate and feelings of worthlessness, sadness or loneliness.
The volunteers were divided into four groups based on the progression of their symptoms: “persistently low” symptoms, “medium decreasing,” “persistently medium” or “high increasing” symptoms. Black adults reported depressive symptoms more often than white adults, the researchers found.
When participants reached an age of about 55, they were given three tests to showcase their thinking and memory skills. Scores ranged from zero to 133, with lower scores representing worse cognition.
The low-symptom group had an average score of 73; medium-decreasing, 71; persistently medium, 66; and high-increasing, 57.
The black participants in the three most symptomatic groups had worse verbal memory, processing speed and executive function scores compared to those with few symptoms.
“Our results suggest that black adults are not only more likely to experience worse depressive-symptoms trajectories, but these symptoms may lead to worse repercussions on thinking and memory as early as middle age,” said study author Leslie Grasset of the University of Bordeaux in France. “This may help explain some of the disparities in dementia risk at older age.”
Among white participants, those in the high-symptom group had worse verbal memory and processing speed scores than those in the low-symptom group.
The findings were published in the online issue of Neurology, the medical journal of the American Academy of Neurology.
The researchers noted one limitation of their study was that participants self-reported their symptoms — and they may not have done so accurately. Clinical diagnoses of depression weren’t available to the study authors.
Dementia is characterized by a progressive decline in brain function. Old age, a brain injury, a family history of dementia and poor habits such as smoking are risk factors.
Nearly 6 million Americans have Alzheimer’s disease and related dementias, according to the Centers for Disease Control and Prevention. That number is projected to grow to 14 million people by 2060.
5 ways to reduce dementia risk
Though there is no surefire way to prevent dementia, Johns Hopkins Medicine recommends five healthy steps to lower your risk.
- Manage high blood pressure
- Address diabetes
- Stop smoking
- Reach a healthy weight — and stick to it
- Exercise regularly