"The processes that lead to dementia begin long before signs of the disease become apparent, and previous research has shown that Black adults have a higher risk of dementia than white adults," said study author Leslie Grasset, PhD, of the University of Bordeaux in France, in a press release.
For the current study, researchers analyzed data from 3, 117 people with an average age of 30 years old at the beginning of the study. Just under half of the participants were Black, and the rest were white. Every five years for 20 years, participants completed a questionnaire to assess their levels of depressive symptoms such as concentration problems, feelings of worthlessness, sadness or loneliness, and changes in appetite or sleep.
The researchers divided the participants into four groups according to how their symptoms progressed over time: persistently low symptoms, medium decreasing symptoms, and persistently medium or high increasing symptoms.
Participants then undertook three tests to examine their thinking and memory skills at an average age of 55 years old. Ultimately, the researchers found that more depressive symptoms experienced throughout early-mid adulthood correlated with lower cognitive scores. The effect was especially prominent among Black individuals.
"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. This may help explain some of the disparities in dementia risk at older age,” said Gresset.
"Having more depressive symptoms may be due to inequalities in socioeconomic resources such as housing and income, as well as access to health care and treatment. Racial inequalities should be accounted for when designing interventions to reduce a person's risk of dementia,” she added.
Sources: Science Daily, Neurology
