Table 2

Non-motor symptoms in the premotor PD

Commonly associated—with reasonable evidence base
Hyposmia (usually of late onset and idiopathic)10 times increase in risk of developing PD;+abnormal DATScan—43% develop motor PD in 4 years33
Rapid eye movement sleep behaviour disorder25–40% risk of developing a synucleinopathy at 5 years;
40–65% risk of developing a synucleinopathy at 10 years34
Constipation2.7–4.5 times increased risk of PD35
Depression2.4 times increased risk of developing PD36
Described associations
Excessive daytime sleepiness3.3 times increased risk of PD37
Fatigue (a sense of exhaustion as opposed to sleepiness)In 45%—a premotor symptom38
Pain (often unilateral and in affected limb)34% increased risk of PD39
Erectile dysfunction3.8 times increased risk of PD40
  • PD, Parkinson's disease.