Clinical Implication of "Closing-in" in Patients with Dementia

ABSTRACT

BACKGROUND: "Closing-in" phenomenon is defined as a tendency to close in the model while copying tasks. This unique phenomenon is one of the constructional apraxia often observed in dementia, especially in Alzheimer's disease (AD). The aim of this study is to investigate the usefulness of "closing-in" in the differential diagnosis of AD and subcortical vascular dementia, and to clarify what the associated factors to this phenomenon are. METHODS: Based on copying data of alternating square and triangle in younger control, we operationally defined "closing-in". "Closing-in" in copied figure was classified into three types overlap, adherent and near types. With this criteria, we analyzed the incidence of "closing-in" in younger control (N=30), elderly control (N=22), AD (N=64), and subcortical vascular dementia (N=31). RESULTS: Compared with subcortical vascular dementia, AD patients had a significantly higher occurrence of "closing-in" phenomenon. Among "closing-in" type, overlap and adherent type was exclusively occurred in AD. A discriminant analysis, calculated by combining results obtained by AD, showed that symptom onsets with age. Korean Mini-Mental State Examination, Clinical Dementia Rating Scale, Rey-Osterrieth Complex Figure Test were significantly correlated with "closing-in". In EEG mapping, though AD patients with apraxia had significantly lower alpha spectra power in all fields, there is no statistical difference between patients with closing-in and those without. CONCLUSIONS: This study suggests that "closing-in" phenomenon was a phase- and AD-specific useful tool for differential diagnosis with subcortical vascular dementia. Moreover, overlap and adherent subtypes of "closing-in" was highly specific in AD, so further clinical study may be promising.