Prevalence of Amyloid Positron Emission Tomographic Positivity in Poststroke Mild Cognitive Impairment

Abstract

Background and Purpose - Mild cognitive impairment (MCI) is common after stroke and associated with poor outcome. However, the mechanisms underlying poststroke MCI (PS-MCI) are insufficiently understood. We performed amyloid-β positron emission tomography (PET) in a prospective cohort of stroke survivors to determine the role of amyloid pathology in PS-MCI. Methods - We studied 178 consecutive patients enrolled into the prospective DEDEMAS study (Determinants of Dementia After Stroke). Follow-up visits 6 months post stroke included detailed cognitive testing, standardized magnetic resonance imaging, and amyloid-β imaging using flutemetamol (18 F) PET. MCI was defined by the modified Petersen criteria. Amyloid-positivity was assessed visually and quantitatively. Fifty-six (31%) patients agreed to undergo PET imaging. Results - Thirty-eight (68%) patients who consented to PET imaging had PS-MCI. Visual assessment revealed amyloid PET positivity in 2 (5%) of the 38 PS-MCI patients and in 2 (11%) of the 18 cognitively healthy stroke survivors. There was no correlation between flutemetamol (18 F) standardized uptake value ratios and cognitive scores in the 56 patients. PS-MCI patients had significant cognitive impairments on executive function (P<0.01) and memory tests (P<0.01) when compared with cognitively healthy stroke survivors (P<0.01). Conclusions - The prevalence of amyloid-pathology in patients with PS-MCI is not increased when compared with cognitively healthy stroke survivors and to recent estimates for cognitively healthy elderly subjects. Factors other than amyloid-pathology likely contribute to the development of PS-MCI. Clinical Trial Registration - URL: http://www.clinicaltrials.gov. Unique identifier: NCT01334749.