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Prior work on patients with Parkinson's disease (PD) has shown that the administration of dopaminergic medication in the early to intermediate stages of PD benefits (motor) functions associated with the dopamine-depleted dorsal striatal circuitry but may 'overdose' and interfere with (cognitive) functions associated with the relatively intact ventral striatal circuitry. The present study aimed to elucidate this so-called dopamine overdose hypothesis for the action control domain. Using a within-subject design in a sample of 13 people with PD, we evaluated the effect of dopaminergic medication on two cognitive processes underlying goal-directed behaviour, namely action selection and initiation through event binding and conflict adaptation. We also investigated whether individual differences in the magnitude of medication effects were associated across these processes. Results showed no indications that dopaminergic medication affects action selection and initiation or conflict adaptation in PD patients. Additionally, we observed no correlations between both cognitive processes nor between individual differences in medication effects. Our findings do not support the notion that dopaminergic medication modulates action control processes, suggesting that the dopamine overdose hypothesis may only apply to a specific set of cognitive processes and should potentially be refined., (© 2022 The Authors. Journal of Neuropsychology published by John Wiley & Sons Ltd on behalf of The British Psychological Society.)

Parkinson's disease (PD) has increasingly been associated with auditory dysfunction, including alterations regarding the control of auditory information processing. Although these alterations may interfere with the processing of speech in degraded listening conditions, behavioural studies have generally found preserved speech-in-noise recognition in PD. However, behavioural speech audiometry does not capture the neurophysiological mechanisms supporting speech-in-noise processing. Therefore, the aim of this study was to investigate the neural oscillatory mechanisms associated with speech-in-noise processing in PD. Twelve persons with PD and 12 age- and gender-matched healthy controls (HCs) were included in this study. Persons with PD were studied in the medication off condition. All subjects underwent an audiometric screening and performed a sentence-in-noise recognition task under simultaneous electroencephalography (EEG) recording. Behavioural speech recognition scores and self-reported ratings of effort, performance, and motivation were collected. Time-frequency analysis of EEG data revealed no significant difference between persons with PD and HCs regarding delta-theta (2-8 Hz) inter-trial phase coherence to noise and sentence onset. In contrast, significantly increased alpha (8-12 Hz) power was found in persons with PD compared with HCs during the sentence-in-noise recognition task. Behaviourally, persons with PD demonstrated significantly decreased speech recognition scores, whereas no significant differences were found regarding effort, performance, and motivation ratings. These results suggest that persons with PD allocate more cognitive resources to support speech-in-noise processing. The interpretation of this finding is discussed in the context of a top-down mediated compensation mechanism for inefficient filtering and degradation of auditory input in PD., (© 2021 Federation of European Neuroscience Societies and John Wiley & Sons Ltd.)

Parkinson's disease (PD) is a neurological disorder associated primarily with motor symptoms such as tremor, slowness of movement, and difficulties with gait and balance. Most patients take dopaminergic medication to improve their motor functions. Previous studies reported indications that such medication can impair higher cognitive functions (cf. dopamine overdose hypothesis). In the present study, we examined the effect of medication status on conflict adaptation. PD patients performed a Stroop task in which we manipulated the proportion of congruent and incongruent items, thereby allowing us to explore conflict adaptation. The use of mouse movements allowed us to examine the action dynamics of conflict adaptation in PD, and their sensitivity to dopaminergic medication. Each patient performed the same task twice: once without making changes to their regular medication regime, and once after overnight withdrawal from their medication. Results showed that medication improved mouse movements and alleviated motor symptoms. Moreover, patients' mouse movements were modulated as a function of the proportion congruency manipulation, revealing conflict adaptation in PD, which was unaffected by medication status. The present study extends earlier work on conflict adaptation in PD where reduced transient (trial-by-trial) conflict adaptation was observed ON compared to OFF medication (Duthoo et al., 2013, Neuropsychology, 27, 556). Our findings suggest that more sustained cognitive control processes may not be sensitive to dopamine overdose effects., (© 2017 The British Psychological Society.)

Neurotropin was found to reduce brain oedema in an experimental model of brain infarction in the guinea-pig. A randomized double-blind controlled trial with Neurotropin was performed in 220 patients admitted within 24 h after an acute ischemic stroke. 35 of the neurotropin and 41 of the placebo-randomized patients had to be excluded. 10 included patients in the neurotropin and 13 in the placebo-treated group died within the study period of 15 days. A better clinical outcome was observed in the 65 included surviving neurotropin compared with the 56 placebo-treated patients. The size of the infarct and of the oedema zones was significantly more decreased on CT scans from Day 11 compared with Day 3 after stroke in the neurotropin than in the placebo treated group. Neurotropin is helpful in treating brain oedema, related to acute ischemic stroke.