Aim To investigate the composition of saliva in patients with Parkinson's disease (PD).

Methods Saliva was collected from 16 patients with PD and 22 age-matched controls. Salivary DJ-1 concentrations were measured with quantitative immunoblotting; total protein concentration with a BCA assay; amylase with an amylase activity assay; and mucin concentrations with periodic-acid Schiff stained SDS gels.

Results Salivary flow rate was not significantly different between patients and controls. Patient saliva showed increases in DJ-1 concentration (0.84 vs 0.42 µg/ml, p=0.001) and total protein concentration (8.4 vs 5.0 mg/ml, p=0.001). In patients, adjusted DJ-1 levels correlated with disease severity measured with the Unified Parkinson's Disease Rating Scale (p=0.019). Concentrations of amylase, but not mucins, were elevated in the saliva of patients (0.127 vs 0.061 units/ml, p<0.001) and correlated positively with both total protein (p<0.001) and DJ-1 concentration (p<0.013).

Conclusions This preliminary study suggests that the saliva of patients with PD is different in composition to that of controls, which supports the notion that saliva may be a good candidate for biomarker discovery in PD. Altered protein secretion may be a manifestation of autonomic dysfunction in PD.