A multicenter, prospective, 24-week follow-up study on cognitive profiles in patients with mild cognitive impairment

Mild cognitive impairment (MCI) is a heterogeneous condition with a variety of clinical outcomes and they are at risk to develop Alzheimer's disease or other dementia. The aims of this study are to assess the specific patterns of cognitive profiles and to demonstrate a change from baseline to 24 week in patients with mild cognitive impairment using detailed neuropsychological test. We consecutively recruited 120 MCI patients at baseline according to the Petersen's diagnostic criteria, who visited to the memory clinics in Pusan-Kyeongnam province between September 1, 2008 and January 30, 2009. We analyzed the patients who fulfilled inclusion and exclusion criteria for MCI. They were classified by four subtypes of MCI according to their deficits in major cognitive domains; amnestic single domain MCI (amci-s), amnestic multi-domain MCI (amci-m), non-amnestic single MCI (namci-s) and non-amnestic multiple MCI (namci-m). Four groups of MCI were evaluated by Seoul Neuropsychological Screening Battery Dementia Version (SNSB-D) Test. The 83 patients with MCI at 24-week follow-up were classified into four subtypes. The most frequent subtype is amnestic multi-domain MCI. Each frequency of MCI subtypes was as follows: amci-s (n = 21, 25.3%), amci-m (n = 53, 63.9%), namci-s (n = 5, 6.0%) and amci-m (n = 4, 4.8%). The SNSB-D scores of the each subtypes of MCI patients were as follows: total MCI (154.9 ± 32.6), amci-s (171.0 ± 33.8), amci-m (146.5 ± 31.0), namci-s (180.2 ± 17.5), namci-m (151.0 ± 16.2). At 24-week follow-up, conversion rate to Alzheimer's disease was 2.4% (n = 2) from a subtype of amnestic multi-domain MCI. The frequency of MCI subtypes was changed into 25.5% of amci-s, 42.1% of amci-m, 16.9% of namci-s, 7.2% of namci-m and normal cognition of 6.0%. After 24 weeks, patients with MCI showed some changes in cognitive scores on the SNSB-D compared with baseline state. The mean differences of total scores of SNSB-D in patients with MCI were as follows; total MCI (-12.5 ± 18.7), amci-s (-11.7 ± 19.6), amci-m (-12.6 ± 19.9), namci-s (-13.0 ± 9.7), namci-m (-15.3 ± 5.3). Our study shows that the most frequent subtype of MCI was amnestic multi-domain MCI and this subtype has a higher tendency of conversion to Alzheimer's disease.