The association between non-motor symptoms in Parkinson's disease and age at onset

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.

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.

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).

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.