The pathophysiology of restless legs syndrome (RLS) is associated with central dopaminergic system dysfunction leading to speculations that RLS may be common in those neurodegenerative diseases with dopaminergic cell loss. However, since RLS is a very common condition, the co-occurrence with less frequent disorders such as the neurodegenerative diseases might be a matter of chance. Currently, no data suggests that patients with sporadic and familial RLS are at increased risk for developing a neurodegenerative disease. In particular, whether RLS is associated with Parkinson's disease has not been established. Only a few studies have directly addressed this issue, and these have methodological limitations yielding conflicting results. Few studies have assessed the frequency of RLS in other neurodegenerative disorders. In several autosomal dominant spinocerebellar ataxias, particularly in Machado-Joseph disease, a higher frequency of RLS is reported than could be accounted for in the general population. Two anecdotal publications have reported the presence of RLS in patients with Huntington's disease and hereditary spastic paraparesis. There are no studies that have examined the association between RLS and other neurodegenerative diseases, such as Alzheimer's disease, frontotemporal dementia, dementia with Lewy bodies, multiple system atrophy, progressive supranuclear palsy, and corticobasal degeneration. .