. 2015 Oct 17;5(4):681–697. doi: 10.3233/JPD-150685

Table 2.

Nonmotor symptoms in prodromal PD

Nonmotor symptom	May occur prior to motor symptoms	Timespan before motor onset	Sensitivity for future PD	Specificity for future PD	Reference
Sensory symptoms
Hyposmia	++	Medium (up to	High (>80% PD	Low (>30% of elderly	[7, 9, 16, 17, 49]
5–10 years)	patients affected)	have hyposmia)
Visual abnormalities	+	Unknown (in RBD up to 10 years)	Unknown	Unknown	[14, 50]
(e.g. reduced colour vision)
Pain	+/-
Neuropsychiatric symptoms
Depression and anxiety	++	Medium (up to 10 years)	Low (30–40%	Low (common in the	[7, 8, 12, 13]
		of PD patients affected)	elderly population)
Anhedonia and apathy	+/-				[7]
Frontal executive dysfunction	+/-
Behavioural symptoms
Quitting smoking	+	Long (mean 10 years)	Unknown	Unknown	[51, 52]
Autonomic dysfunction
Constipation	++	Long (potentially more	Moderate (30–60%	Low (common in the	[7–11, 53]
		than 10–20 years)	of PD patients affected)	elderly population)
Orthostatic hypotension	+/-				[8]
Urogenital dysfunction	+/-				[8]
Sleep disorders
RBD	++	Long (potentially more	Low to moderate (30–50%	High (>80% of idiopathic	[14, 15, 54]
		than 10–20 years)	of PD patients affected)	RBD patients will develop
Lewy-body disorders)
Excessive daytime somnolence	+	Medium (up to 5–10 years)	Unknown	Unknown	[7, 55]
Sleep fragmentation and insomnia	+/-
PLMS/RLS	+/-

Abbreviations: PD, Parkinson’s disease; PLMS, periodic limb movements during sleep; RBD, rapid eye movement sleep behavior disorder; RLS, restless legs syndrome. ++ = robust evidence from more than one prospective population-based or cohort study, + = evidence from one prospective population-based or cohort study or more than one retrospective population-based or cohort study, +/- = no evidence from population based or cohort studies, but respective nonmotor symptom is frequently seen in early PD [43–45].