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 disorder | 25–40% risk of developing a synucleinopathy at 5 years; 40–65% risk of developing a synucleinopathy at 10 years34 |
| Constipation | 2.7–4.5 times increased risk of PD35 |
| Depression | 2.4 times increased risk of developing PD36 |
| Described associations | |
| Excessive daytime sleepiness | 3.3 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 dysfunction | 3.8 times increased risk of PD40 |
PD, Parkinson's disease.