Microbleeds are associated with an increased risk of cognitive deterioration and dementia in the general population, according to study results published in JAMA Neurology.
While cerebral microbleeds are thought to be markers of brain damage, their impact on cognition is not well understood. To better understand their probable role in dementia, Saloua Akoudad, MD, PhD, of the University Medical Center Rotterdam in the Netherlands, and colleagues conducted the Rotterdam Study, a prospective, population-based study to assess the presence, number, and location of microbleeds in the general population at baseline using MRI.
The Rotterdam Study collected MRI data from 4841 participants 45 years or older from August 2005 to December 2011. Participants underwent neuropsychological testing at 2 time points an average of 5.9 years apart and were evaluated for incident dementia throughout the study, which concluded on January 1, 2013.
In total, 3257 participants (54.7% women; mean age 59.6 years) completed baseline and follow-up testing. Microbleeds were prevalent in 15.3% of the cohort (17.8% 60-69 years, 38.3% ≥80 years), with the presence of 4 or more microbleeds associated with cognitive decline. Specifically, lobar (with or without cerebellar) microbleeds were associated with a decline in executive function (mean difference in z score, −0.31; 95% CI, −0.51 to −0.11; P= .003), information processing (mean difference in zscore, −0.44; 95% CI, −0.65 to −0.22; P< .001), and memory function (mean difference in z score, −0.34; 95% CI, −0.64 to −0.03; P= .03), while microbleeds in other areas of the brain were associated with a decline in information processing and motor speed (mean difference in z score, −0.61; 95% CI, −1.05 to −0.17; P= .007). After approximately 4 and a half years, 72 of the participants developed dementia, 53 of whom developed Alzheimer’s dementia. After adjustment for age, sex, and education level (HR, 2.02; 95% CI, 1.25-3.24), the presence of microbleeds was found to be associated with an increased risk of dementia and Alzheimer’s dementia (HR, 2.10; 95% CI, 1.21-3.64).
“Microbleeds thus mark the presence of diffuse vascular and neurodegenerative brain damage,” the authors concluded.