Abstract
BACKGROUND: Hearing impairments are manifestations of Parkinson's disease (PD). We aimed to assess central auditory processing (CAP) functions with PD and their predictors. METHODS: This was a cross-sectional study. It included 35 patients (male = 21; female = 14). The severity of PD was assessed using modified Hoehn and Yahr Scale. The severities of depression and cognitive manifestations were assessed using Beck Depression Inventory II (BDI-II) and Mini Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA). Participants underwent audiometry and testing of CAP using dichotic digit (DDT), duration pattern (DPT) and speech in noise (SPIN) tests. RESULTS: Patients had mean age at presentation of 56.66 ± 11.05 yrs and mean duration of PD of 4.77 ± 2.73 yrs. Among were ~69% of patients were in early stages of the disease. Compared to controls (n = 25), patients had poor cognition [MMSE: 20.98 ± 2.36, P = 0.001; MoCA: 18.41 ± 3.00, P = 0.001], hearing impairment at high frequencies (4000 HZ), higher speech reception threshold (SRT) (P = 0.001) and worse performance in DDT (P = 0.0001), DPT (P = 0.0001) and SPIN (P = 0.001). These impairments were independently correlated with cognitive deficits (DDT: P = 0.036; DPT: P = 0.050, SPIN: P = 0.023). CONCLUSIONS: CAP dysfunctions occur in early stages of PD. They include impairments in auditory discrimination, spatial perception, binaural integration, temporal ordering or sequencing, and selective attention. The DDT, DPT and SPIN are useful battery measures for testing CAP with PD. Dopamine deficiencies in PD at different auditory pathway levels including the brainstem and cortico-subcortical levels and neurodegenerative diffuse PD pathology can be the causes of CAP impairments.