Intellectual Functioning of Persons With Idiopathic Parkinsonism

Initial data from an investigation of intellectual functioning of patients with parkinsonism is reported. Forty-seven white, American born, noninstitutionalized persons with idiopathic parkinsonism and without any other demonstrable disease of the central nervous system, and a matched group of controls were studied. Subjects were given four tests of intellectual ability adapted from Guilford's comprehensive model of intelligence (10). A method of testing with a computer was employed so that patients could test themselves repeatedly with alternate and equivalent forms. Analysis of the time scores led to the division of patients into two groups, a faster group with a time distribution similar to their controls, and a slower group of patients who were slower than their controls on all four tests. The slower group is significantly older and significantly more disabled, but has not had parkinsonism significantly longer than the faster group. The slower patients generally score somewhat lower in intellectual ability than their controls, while intellectual ability of the faster patients seems unimpaired when compared to their controls. These results suggest that akinesia may be more characteristic of patients in whom the onset of the disease is late in life, and that late onset and akinesia tend to be associated with intellectual deterioration.