Effect of L-dopa on dementia-related rigidity.

L-dopa 100 mg plus benserazide 25 mg versus placebo were given 3 times daily to 14 consecutive patients with dementia and rigidity. The treatment was crossed over to the alternative therapy after a 7-day period. Despite a mean 60% raise in CSF-HVA during L-dopa administration, no patient responded to the treatment. These data suggest that dementia-associated rigidity differs, at least, pharmacologically from parkinsonian rigidity.