Apraxia in mild cognitive impairment and Alzheimer's disease: validity and reliability of the Van Heugten test for apraxia.

AIM To assess the reliability and validity of the Van Heugten test for apraxia (VHA), developed for and used in stroke patients, in a memory clinic population. Furthermore, we assess the presence and severity of apraxia in mild cognitive impairment (MCI) and Alzheimer's disease (AD) and investigate which AD patients are likely to develop apraxia. METHODS We included 90 controls (age: 60 ± 9 years, MMSE: 28 ± 2), 90 MCI patients (age: 65 ± 7 years, MMSE: 26 ± 2) and 158 AD patients (age: 66 ± 8 years, MMSE: 20 ± 5). Apraxia was evaluated by the VHA assessing ideational and ideomotor praxis. We retested 20 patients to assess reliability. RESULTS Intrarater reliability was 0.88 and interrater reliability was 0.73. AD patients performed worse on the VHA (median: 88; range: 51-90) than controls (median: 90; range: 88-90) and MCI patients (median: 89; range: 84-90) (both p < 0.001). Apraxia was prevalent in 35% of AD patients, in 10% of MCI and it was not observed in controls (0%; p < 0.001). In AD, dementia severity was the main risk for apraxia; 15% of mildly versus 52% of moderately demented patients had apraxia (OR = 6.7, 95% CI 2.9-15.6). The second risk factor was APOE genotype. APOE ε4 noncarriers (47%) were at increased risk compared to carriers (30%) (OR = 2.1, 95% CI 1-4.7). CONCLUSION Apraxia can be reliably measured with the VHA and is present in a proportion of patients with MCI and AD. The presence of apraxia in AD is related to dementia severity and APOE ε4.