The different syndromes in Parkinson's disease: an overview

Parkinson's disease is a heterogeneous disorder in its presentation and progression, a fact important in clinical practice and in research. Clinical experience as well as data driven approaches have guided the attempts to define more homogeneous populations, i.e., different syndromes or subtypes, that share prognostic and other features. The first approach led to subtypes distinguished by age of onset, motor phenotype or the presence of nonmotor features. The second yielded subtypes defined by both motor and nonmotor symptoms. Finally, monogenic Parkinson's disease is also considered a subtype, as carriers of the same mutation likely share the same pathogenic mechanism.