The Parkinsonian syndrome and its dopamine correlates

The urinary excretion of free dopamine in 37 untreated parkinsonian patients correlated negatively with the severity of rigidity and akinesia (p less than 0.025) and with total neurologic deficit (p less than 0.05). In a parallel study of psychiatric patients, those with the lowest levels of urinary free dopamine before treatment were the most vulnerable to, and developed the most severe, secondary parkinsonian rigidity (p less than 0.005), akinesia (p less than 0.05), and total deficit (p less than 0.01) when they were subsequently treated for two weeks with trifluoperazine. In neither study was there a significant correlation between free urinary dopamine and tremor. These studies directly associate the level of free dopamine in the urine with the severity of the parkinsonian syndrome. Therefore, although many peripheral sources contribute to urinary free dopamine, a small decrease in the level may actually reflect the severity of the disturbance of central dopamine metabolism and the known deficiency of dopamine in the neurons of the parkinsonian brain.