[Parkinsonism in Alzheimer's disease]

Parkinsonism occurs frequently in the patients with Alzheimer type dementia (ATD). The frequency ranges from 9% to 100% of ATD patients, depending on samples, clinical instruments and stages of illness. Several studies have described that rigidity and hypokinesia are the most prevalently observed signs of parkinsonism, and that resting tremor is less. The clinical progress of patients with parkinsonism is more rapid than those of patients without parkinsonism. Patients with parkinsonism are frequently associated with psychiatric symptoms such as depression and delusion. The pathogenesis of parkinsonism in ATD remains to be elucidated, but it should be noted that some cases with parkinsonism correlates with Parkinson's disease pathologic condition, and some have diffuse Lewy body disease.