Mild cognitive impairment: applicability of research criteria in a memory clinic and characterization of cognitive profile.
BACKGROUND: We explored the applicability of recently proposed research criteria for mild cognitive impairment (MCI) in a memory clinic and changes in case definition related to which memory tests are used and the status of general cognitive function in MCI. METHOD: A total of 166 consecutive GP referrals to the Cambridge Memory Clinic underwent comprehensive neuropsychological and psychiatric evaluation. RESULTS: Of 166 cases, 42 were excluded (significant depression 8, established dementia 29 and other disorders 5). Of 124 non-demented, non-depressed patients, 72 fulfilled Petersen's criteria for amnestic MCI based upon verbal memory performance [the Rey Auditory Verbal Learning Test (RAVLT)] and 90 met criteria if performance on verbal and/or non-verbal memory tests [the Rey figure recall or the Paired Associates Learning test (PAL)] was considered. Of the 90 broadly defined MCI cases, only 25 had pure amnesia: other subtle semantic and/or attention deficits were typically present. A further 12 were classed as non-amnestic MCI and 22 as 'worried well'. CONCLUSIONS: Definition of MCI varies considerably dependent upon the tests used for case definition. The majority have other cognitive deficits despite normal performance on the Mini-mental State Examination (MMSE) and intact activities of daily living (ADL) and fit within multi-domain MCI. Pure amnesic MCI is rare.