Prevalence and classification of mild cognitive impairment in the Cardiovascular Health Study Cognition Study: part 1.

OBJECTIVE To examine the prevalence of mild cognitive impairment (MCI) and its diagnostic classification in the Cardiovascular Health Study (CHS) Cognition Study. DESIGN The CHS Cognition Study is an ancillary study of the CHS that was conducted to determine the presence of MCI and dementia in the CHS cohort. SETTING Multicenter population study. PATIENTS We examined 3608 participants in the CHS who had undergone detailed neurological, neuropsychological, neuroradiological, and psychiatric testing to identify dementia and MCI. MAIN OUTCOME MEASURES The prevalence of MCI was determined for the whole cohort, and specific subtypes of MCI were examined in detail only at the Pittsburgh, Pa, center (n = 927). Mild cognitive impairment was classified as either MCI amnestic-type or MCI multiple cognitive deficits-type. RESULTS The overall prevalence of MCI was 19% (465 of 2470 participants); prevalence increased with age from 19% in participants younger than 75 years to 29% in those older than 85 years. The overall prevalence of MCI at the Pittsburgh center was 22% (130 of 599 participants); prevalence of the MCI amnesic-type was 6% and of the MCI multiple cognitive deficits-type was 16%. CONCLUSIONS Twenty-two percent of the participants aged 75 years or older had MCI. Mild cognitive impairment is a heterogeneous syndrome, where the MCI amnestic-type is less frequent than the MCI multiple cognitive deficits-type. Most of the participants with MCI had comorbid conditions that may affect their cognitive functions.