A quantitative analysis of apraxia in senile dementia of the alzheimer type: Stage-related differences in prevalence and type

Apraxia is clinically separable from other cognitive dysfunctions and has the potential to interfere with motor performance in everyday living. To determine its prevalence and severity at each stage of senile dementia of the Alzheimer type (SDAT), a quantitative apraxia battery was used in conjunction with comprehensive quantitative cognitive assessments of 142 SDAT subjects who fell into four stages of dementia severity, and 113 elderly persons determined to be intellectually healthy by the same cognitive assessment. Thirty-five percent of the mildly, 58% of moderately, and 98% of severely demented SDAT subjects showed apraxia. When ideomotor and ideational apraxia were considered separately, ideomotor apraxia was apparent in mild dementia, while ideational apraxia was found only in moderate and severe dementia. When a covariate analysis was employed to test the influence of aphasia that is known to occur in SDAT, ideomotor (but not ideational) deficits were found to be statistically distinct from language impairment. Taken together the findings suggest that ideomotor apraxia may be tied to loss of functional independence in individuals with SDAT.