Cannabis in movement disorders

Central cannabinoid receptors are densely located in the output nuclei of t he basal ganglia (globus pallidus, substantia nigra pars reticulata), sugge sting their involvement in the regulation of motor activity. Furthermore, t here is evidence that endogenous cannabinoid transmission plays a role in t he manipulation of other transmitter systems within the basal ganglia by in creasing GABAergic transmission, inhibiting glutamate release and affecting dopaminergic uptake. Most hyperkinetic and hypokinetic movement disorders are caused by a dysfun ction of basal ganglia-thalamo-cortical loops. It has been suggested that a n endogenous cannabinoid tone participates in the control of movements and, therefore, the central cannabinoid system might play a role in the pathoph ysiology of these diseases. During the last years in humans a limited number of clinical trials demonst rated that cannabinoids might be useful in the treatment of movement disord ers. Despite the lack of controlled studies there is evidence that cannabin oids are of therapeutic value in the treatment of ties in Tourette syndrome , the reduction of levodopa-induced dyskinesia in Parkinson's disease and s ome forms of tremor and dystonia. It can be speculated that cannabinoid ant agonists might be useful in the treatment of chorea in Huntington's disease and hypokinetic parkinsonian syndromes.