We aimed to investigate the impact of cerebral microbleeds (CMBs) on the cognitive decline of patients with Alzheimer’s disease (AD) in a tertiary memory clinic.

CMBs are frequently observed in patients with AD, as well as in general population. They could contribute to cognitive impairment in the general population. But the impact of CMBs on cognition remained debatable in patients with AD, because of other contradictory clinical findings.

Patients diagnosed with AD from 1997 to 2017, with at least two consecutive, one-year-apart MMSE scores in the memory clinic of Lille were included. The following characteristics were extracted: demographic characteristics, vascular risk factors, comorbidities, medication, duration of the follow-up, successive MMSE score, dementia rating scale, APOE genotype, MRI, CSF biomarkers. We analyzed the data by a linear mixte model.  

369 patients were included, mostly women (58.8%). The median age at first symptom was 63.3 years old. The median MMSE score at first visit was 24 points. The median duration of follow-up was 4 years. We identified at least one CMB in 20.4% of patients, mostly single and cortical. Among patients with at least one CMB, the onset of the disease was 7 years later, the white matter hyper-intensities were more severe (43% Vs 14%, p<0.0001), compared to patients without any CMB. There was no difference in CSF biomarkers. During the follow-up, CMBs did not worsen the cognitive decline. The accumulation of new CMBs was significantly higher for patients with previous CMBs (36% Vs 5%, p<0.0001), without affecting the cognition. There was no impact of CMBs on the evolution of brain atrophy.

In this study, patients were relatively young, and the CMB was often single. We did not show a direct impact of CMB on cognition in patients with AD. The presence of CMB was rather a marker of vascular disorder.