COGNITIVE DYSFUNCTION AND IMPAIRED ORGANIZATION OF COMPLEX MOTILITY IN DEGENERATIVE PARKINSONIAN SYNDROMES

Background: A frontostriatal pattern of cognitive decline, consisting of a frontal lobe-like syndrome without genuine cortical defects such as amnesia, apraxia, aphasia, or agnosia, is well established in basal ganglial diseases. Recent pathological investigations, however, have again noted cortical damage in progressive supranuclear palsy (PSP), s uggesting that cortical defects could be present. Objectives: To delin eate the pattern of cognitive impairment and to detect higher-order mo tor impairments (including ideomotor apraxia) in parkinsonian syndrome s. Patients and Methods: We assessed ideomotor apraxia, and simple and sequential tapping in patients with Parkinson disease, multiple syste m atrophy, and PSP with similar disease severity, age range, and educa tion. We also administered a comprehensive battery of neuropsychologic al tests to examine general intelligence, memory, executive functions, attention, and visuospatial orientation. The results were compared be tween groups and with a matched normal control group. Results: Sequent ial tapping and the imitation of sequences of gestures were impaired i n all patient groups, with patients with PSP performing worse than the other groups. Based on ideomotor apraxia scores and a qualitative ana lysis of errors, 3 patients with PSP and 2 with multiple system agroph y were considered apraxic. General intelligence and executive function s were compromised in all patient groups. The impairment of patients w ith PSP was more pervasive than that of the other groups, and included compromise of visuospatial functions, attention, and memory. Discrimi nant analysis of all cognitive and motor tests showed that the tapping and ideomotor apraxia tests best identified the patients vs control s ubjects. Conclusions: The presence of cortical as well as subcortical damage in patients with PSP and those with multiple system atrophy is indicated by the presence of pervasive cognitive and motor disturbance s in the former, substantial motor disorganization in the latter, and the finding of ideomotor apraxia in some patients with these diseases. Furthermore, the discovery that tests of motor and gesture best ident ified all patients vs control subjects is consistent with the existenc e of a common motor disorganization in these parkinsonian syndromes, i n agreement with the known damage to the corticostriatal pathways in t hese conditions.