Introduction and Objective: Cerebral microbleeds (CMBs) have been acknowledged as a manifestation of age-related cerebral small vessel diseases. The prevalence of CMBs has been reported around 4.5%-15.3% in the general population, and could reach as high as 35.7% in people >80 years old. Studies have evaluated the effects of CMBs on cognitive functions, however, the results about the influence of CMB location (e.g. deep/infratentorial or lobar) are inconsistent. Besides, there are scanty CMB studies of the Asian community-based population and even fewer have investigated in the impacts of CMBs on different cognitive domains. The present study aimed to evaluate the correlations between the CMBs and cognitive functions in a Taiwan community-based population. We determined whether the number and location of CMB had impacts on a variety of cognitive functions.
Methods: Study subjects were from the community-based I-Lan Longitudinal Aging Study. Subjects with dementia and stroke were excluded. The cognitive domains including verbal memory, language, visuospatial executive, and verbal executive functions were evaluated. The number and location of CMBs were revealed by the 3T susceptibility weighted imaging MRI.
Results: There were 401 subjects [63.87(8.82) years, 193(48.1%) men] included. CMBs were found in 11.7% of population. The results showed that lobar CMBs were significantly associated with poorer visuospatial instead of verbal executive function independent of age, gender, education, hypertension and the other markers of cerebral small vessel diseases. The presence of CMBs in the temporal and frontal lobes determined worse neuropsychological tests involving the visuospatial executive functions, the complex figure test [temporal CMBs: regression coefficient (95% confidence interval) = -4.59 (-9.46 - -0.35), p = 0.035; frontal CMBs: -2.13 (-6.91 - 2.65), 0.381] and clock drawing test [temporal CMBs: -1.55 (-3.17 - 0.10), p = 0.063; frontal CMBs: -1.48 (-3.15 - 0.18), 0.082].
Conclusion: The location is more important than amounts regarding the CMB effects on cognitive functions in non-demented non-stroke healthy subjects. Lobar CMBs, particular in the temporal and frontal lobe, are associated with poorer visuospatial executive function.