Beginning in young adulthood, individuals who suffer from long-lasting depressive symptoms may experience decreased cognitive abilities and memory skills in middle age, as per a recent study published in the online issue of Neurology®. The research also revealed that Black adults are more likely than white adults to experience depressive symptoms.
A recent study found that Black adults are more likely than white adults to experience prolonged depressive symptoms, which can have a negative impact on thinking and memory in middle age. The study, led by Leslie Grasset, PhD, of the University of Bordeaux in France, also discovered that the processes leading to dementia begin long before symptoms appear. Previous research has indicated that Black adults are at a higher risk of developing dementia compared to white adults.
The research involved 3,117 participants with an average age of 30 at the beginning of the study. The findings suggest that extended exposure to elevated depressive symptoms during young adulthood can have long-term consequences, particularly for Black adults.
The participants were assessed for signs of depression every five years over a span of 20 years. During each assessment, they were asked to complete a survey indicating whether they had experienced changes in their appetite or sleep patterns, had difficulty concentrating, or felt feelings of worthlessness, sadness or loneliness. A higher score indicated a greater number of symptoms.
The researchers categorized the participants into four groups based on the progression of their symptoms over time: consistently low symptoms, moderately decreasing symptoms, consistently moderate symptoms, or increasingly high symptoms. The group with persistently low symptoms had a higher percentage of Black participants at 52%.Currently, 70% of the participants belonged to the medium group with increasing depressive symptoms, and some were in the high group as well. Five years later, when the participants were around 55 years old on average, they underwent three tests to assess their cognitive abilities. One of the tests measured processing speed and memory by asking participants to draw symbols that corresponded to numbers as quickly as possible. The scores ranged from zero to 133, with lower scores indicating poorer cognition. The average score for those in the low symptom group was 73, while those in the medium decreasing group had an average score .
The study found that Black participants in the high symptom group had an average score 0.64 standard deviations lower than those in the low symptom group, after accounting for factors like age, physical activity, and total cholesterol. For white participants, the average score for those in the high symptom group was 0.40 standard deviations lower than those in the low symptom group.
The researchers standardized the score for each of the cognitive tests after making adjustments for various factors.The study found that Black participants in the high and medium symptom groups had poorer verbal memory, processing speed, and executive function scores compared to those in the low symptom group. Similarly, 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 suggest that Black adults may experience more severe depressive symptoms and that these symptoms may have a greater impact on cognitive functions.
“As people age, they may experience an increase in depressive symptoms and memory issues,” explained Grasset. “This could help in understanding why there are differences in dementia risk in later life.”
Grasset also noted, “The higher prevalence of depressive symptoms could be linked to disparities in economic resources such as housing and income, as well as access to healthcare and treatment. It’s important to consider racial inequalities when developing strategies to lower the risk of dementia.”
One limitation of the study was that participants self-reported their symptoms, and there was no clinical diagnosis of depression available. It’s possible that some participants may not have accurately reported their symptoms.
