A study published in Neurology® found that prolonged exposure to elevated depressive symptoms in young adulthood may have a negative effect on thinking and memory skills in middle age, especially for Black adults. The study involved 3,117 participants with an average age of 30, with 47% being Black and 53% white. Participants were evaluated for depressive symptoms every five years for 20 years and divided into four groups based on the progression of their symptoms over time. The study found that Black participants were more likely to experience worse depressive symptom trajectories and had more severe effects on thinking and memory skills compared to white participants.
Five years later, participants were given tests to examine their thinking and memory skills. Black participants in the high symptom group had significantly lower cognitive scores compared to white participants. After adjusting for factors such as age, physical activity, and total cholesterol, Black participants in the high symptom group had scores that were 0.64 standard deviations below the average score for the low symptom group, while white participants had scores that were 0.40 standard deviations below. Among Black participants, those with high and medium symptoms had worse verbal memory, processing speed, and executive function scores compared to those in the low symptom group, while white participants in the high symptom group had worse verbal memory and processing speed scores.
The study suggests that racial inequalities in socioeconomic resources, housing, income, and access to healthcare and treatment may contribute to the higher prevalence of depressive symptoms in Black adults. These symptoms may lead to worse repercussions on thinking and memory skills as early as middle age, potentially explaining some of the disparities in dementia risk at older ages. It is important to account for racial inequalities when designing interventions to reduce an individual’s risk of dementia. A limitation of the study was that symptoms were self-reported, and no clinical diagnosis of depression was available, potentially leading to underreporting of symptoms by some participants.
Overall, the study highlights the impact of prolonged exposure to depressive symptoms on thinking and memory in middle age, particularly for Black adults who may experience worse symptoms trajectories. Understanding the factors contributing to these disparities, such as socioeconomic resources and access to healthcare, is crucial in addressing the increased risk of cognitive decline and dementia in certain populations. By addressing these racial inequalities and providing appropriate interventions, it may be possible to reduce the risk of dementia and improve cognitive outcomes in middle-aged and older adults.