Objective: Age at onset is likely to be related to a wide range of problems in Parkinson's disease (PD), including cardinal motor features, motor complications and non-motor symptoms (NMS). This study investigated the effect of the age at onset on NMS. Methods: Two hundred and thirty patients were examined and classified into one of three groups based on age at onset: early onset PD (EOPD) group (<45 years), middle-age onset group (45-64 years) and old-age onset group (>= 65 years). The trends relating to NMS were compared across the three groups. The EOPD and old-age onset groups were separately studied to determine their association to the appearance of non-motor features using logistic regression analysis. Results: There were upward trends in the occurrence of dribbling (P=0.009; all P values are stated for trend), impaired taste/smelling (P=0.016), constipation (P=0.006), urinary urgency (P=0.002), nocturia (P=0.018), hallucinations (P=0.016) and acting out during dreams (P=0.011) with the increase of age at onset. Older age at onset is an independent risk factor for dementia (OR=8.42, CI 3.16-22.44), dribbling (OR=4.14, CI 1.93-8.87), impaired taste/smelling (OR=2.23, CI 1.20-4.13), constipation (OR=3.42, CI 1.88-6.24), incomplete bowel emptying (OR=2.23, CI 1.19-4.20), urinary urgency (OR=2.58 CI 1.46-4.57), nocturia (OR=2.65, CI 1.49-4.71), hallucinations (OR=5.32, CI 1.78-15.97), dizziness (OR=3.03, CI 1.59-5.79), falling (OR=3.60, CI 1.67-7.77), insomnia (OR=2.29, CI 1.28-4.11), intense vivid dreaming (OR=2.10, CI 1.21-3.66) and acting out during dreams (OR=2.23, CI 1.24-4.01). Conclusions: PD patients with different ages at onset present clinically different symptoms in terms of NMS. Old-age onset PD is characterized by more olfactory and sensory symptoms, autonomic symptoms, sleep disorders, dementia and psychosis compared to EOPD. (C) 2013 Elsevier B.V. All rights reserved.