Subtypes and Their Clinical Characteristics of Mild Cognitive Impairment (MCI): Cross Sectional Study

ABSTRACT

BACKGROUND: Mild cognitive impairment (MCI) represents a transitional state between the cognitive changes of normal aging and very early dementia. Recently, the published MCI classification in `The Current Concepts in MCI Conference' suggested subtypes of MCI (amnestic, single nonmemory domain, multiple domains slightly impared) based on recognized heterogeneity. The purpose of this study was to ascertain the existence of subtypes of MCI and investigate their relative prevalence and clinical characteristics. METHODS: We recruited the MCI patients according to the consensus criteria of MCI. We classified them into 3 subtypes of MCI by our working criteria based on the definitions of MCI subtypes and then calculated their respective prevalence. We described their various clinical variables including demographic features, symptoms on the first visit, neuroimaging findings, and the genotype of apolipoprotein E. RESULTS: Sixty patients (36 females and 24 males) were enrolled as MCI and analyzed. The prevalence of each subtype (amnestic, single nonmemory domain, multiple domains slightly impared) were 13 (21.67%), 24 (40.0%), and 23 (38.33%) respectively, suggesting the most prevalent type was the single nonmemory domain type. MCI cases with subcortical vascular features were 18 (11 single nonmemory domain and 7 multiple domains slightly impaired). The ApoE epsilon4 carriers were about 50% of tested patients. CONCLUSIONS: We ascertained the existence of MCI subtypes and investigated their prevalence and various clinical features. In evaluation of MCI patients, we should keep the notion of heterogeneity and subclassification in mind.