Enhanced taste recognition following subacute treatment with the dopamine D2/D3 receptor agonist pramipexole in healthy volunteers.
Kaltenboeck A., Halahakoon DC., Harmer CJ., Cowen P., Browning M.
BACKGROUND: Patients with Parkinson's disease (PD) show impaired performance in taste recognition tests, which suggests a possible dopaminergic influence on gustatory functioning. To experimentally test this hypothesis, we assessed whether pharmacological manipulation of dopaminergic signalling in healthy volunteers can affect performance in a standardised taste recognition test. METHODS: Physically and mentally healthy volunteers (n = 40, age 18 to 43 years) were randomly allocated to treatment with either pramipexole or placebo using a double-blind, parallel-group design. After 12 to 15 days of treatment (dose titrated up from 0.25 mg/day of pramipexole salt to 1.0 mg/day), taste recognition performance was assessed using a standardised and validated assay (taste strip test). Additionally, visual analogue scale ratings of subjective pleasantness and disgustingness of taste samples were obtained. RESULTS: Compared to the placebo group, participants receiving pramipexole showed significantly higher total recognition accuracy (MedianPramipexole = 14.0, MedianPlacebo = 13.0, U = 264.5, p = 0.04). This was driven by a higher sensitivity for taste in the pramipexole group. Exploratory analysis of pleasantness and disgustingness ratings of appetitive (sweet) versus aversive (bitter) stimuli suggested that pramipexole treatment was associated with overall blunted hedonic responses, but this effect did not survive the inclusion of nausea (a side effect of treatment) as a covariate in the analysis. CONCLUSIONS: Healthy volunteers who received subacute pramipexole treatment exhibited higher taste recognition performance in comparison to a placebo group. This finding is consistent with a proposed role of the dopaminergic system in gustatory functioning and could have important theoretical and clinical implications.