Long‐range motor performance changes in levodopa‐treated patients with Parkinson's disease

Study of deterioration in long-term treatment of parkinsonism with L-Dopa plus decarboxylase inhibitor

“…Our findings confirm the observations of other authors (Barbeau, 1973;Birdsong and McKinney, 1974;Glass and Grimm, t975;Guillard, 1975;Lieberman et aI., 1975;Rinne et al, 1975;Selby, 1975) that parkinsonian patients treated with L-Dopa alone or combined with a decarboxylase inhibitor show a slow deterioration of their condition aider an impressive initial improvement. A reduced dosage of the compound due to side effects cannot be its cause in the present study, since the 35 patients treated with L-Dopa plus benserazide for 3 years received practically the same mean daily amount of L-Dopa at the time of the best therapeutic response and at the end of the observation period.…”

“…The same arguments speak against reduced efficacy of the decarboxylase inhibitor. This is also made unlikely by reports which describe a deterioration with L-Dopa alone (Barbeau, 1973;Birdsong and McKinney, 1974;Glass and Grimm, 1975;Guillard, 1975;Selby, 1975). If the decarboxylase inhibitor could pass the blood-brain barrier aRer some time of treatment, a concomitant reduction of central side effects could be expected too.…”

“…Aflter treatment with L-Dopa for several years, however, several authors have observed a slow deterioration of the patients' condition in spite of excellent or very good initial results (Barbeau, 1973;Birdsong and McKinney, 1974;Glass and Grimm, 1975;Guillard, 1975;Lieberman et al, 1975;Rinne et aL, 1975;Selby, 1975). We observed the same phenomenon in our patients.…”

Cognitive deficits associated with chronic hepatic encephalopathy and their response to levodopa.

“…Furthermore, the majority of perceptual tests used in both these studies are speed-based and require manipulative skills which are specifically improved by levodopa. As Birdsong and McKinney (1974) have recently emphasized, these perceptual tests neither evaluate the motor component nor isolate the perceptual component.…”

“…Several authors have attributed this improvement entirely to an arousal effect (Cotzias et al, 1969;Godwin-Austen et al, 1969;Yahr et al, 1969;Horvarth and Meares, 1974), others report a specific effect on intellectual functions independent of arousal (Marsh et al, 1971;Loranger et al, 1972), while yet others have pointed out that the tests used failed to evaluate the motor component in the subjects' performance and hence cannot resolve this issue (Birdsong and McKinney, 1974). The tests reported here use computer techniques to maximize the evaluation of different aspects of performance and in the present paper we also use our findings to interpret the conflicting reports in the literature.…”