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This Month in Archives of Neurology
July 2010

This Month in Archives of Neurology

Arch Neurol. 2010;67(7):793-794. doi:10.1001/archneurol.2010.134

Savica and colleaguesArticle review the convincing evidence that the Parkinson disease neurodegenerative process begins many years before the onset of motor manifestations. Initial estimates based on nigral neuropathology or striatal dopamine imaging suggested a 5- to 6-year preclinical period. Epidemiologic studies of nonmotor manifestations such as constipation, anxiety disorders, rapid eye movement sleep behavior disorder, or anemia suggested that the preclinical period extends at least 20 years before the motor manifestations. Olfactory impairment and depression may also precede the onset of motor manifestations; however, the lag time may be shorter. Recognition of a nonmotor preclinical phase spanning 20 or more years should guide the search for predictive biomarkers and the identification of risk or protective factors for Parkinson disease.