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AbstractParkinson’s disease (PD) is histologically characterized by the accumulation of α-synuclein particles, known as Lewy bodies. The second most common neurodegenerative disorder, PD is widely known because of the typical motor manifestations of active tremor, rigidity, and postural instability, while several prodromal non-motor symptoms including REM sleep behavior disorders, depression, autonomic disturbances, and cognitive decline are being more extensively recognized. Motor symptoms most commonly arise from synucleinopathy of nigrostriatal pathway. Glutamatergic, γ-aminobutyric acid (GABA)ergic, cholinergic, serotoninergic, and endocannabinoid neurotransmission systems are not spared from the global cerebral neurodegenerative assault. Wide intrabasal and extrabasal of the basal ganglia provide enough justification to evaluate network circuits disturbance of these neurotransmission systems in PD. In this comprehensive review, English literature in PubMed, Science direct, EMBASE, and Web of Science databases were perused. Characteristics of dopaminergic and non-dopaminergic systems, disturbance of these neurotransmitter systems in the pathophysiology of PD, and their treatment applications are discussed.

What is known and objective The underlying pathophysiology of autism spectrum disorder (ASD) has been linked to immune dysregulation, oxidative stress and excitation‐inhibition imbalance. Among associated symptoms of ASD, management of irritability has gained considerable attention as it complicates adjustment of ASD patients and thus necessitates its pharmacological treatment. Resveratrol is a plant phytoalexin, which has been demonstrated to have neuroprotective effects through its anti‐inflammatory and antioxidant properties. This double‐blind, placebo‐controlled randomized trial was designed to assess the potential therapeutic effects of resveratrol plus risperidone on irritability of ASD patients. Methods Sixty‐two patients were assigned randomly into two groups of resveratrol and placebo. Both groups were treated with risperidone twice daily starting at a dose of 0.5 mg with a dose increase of 0.5 mg per week (for the first 3 weeks). Resveratrol dosage was 250 mg twice per day from the beginning of the study. Using the Aberrant Behavior Checklist‐Community (ABC‐C), patients were assessed for ASD‐related behavioural symptoms at baseline, week 5 and week 10. The frequency of adverse events was recorded using a checklist containing 25 possible side effects, including general, gastrointestinal, neurological and cardiovascular complications. Results and discussion Improvements in primary outcome measure (irritability) and three secondary outcome measures (lethargy/social withdrawal, stereotypic behaviour and inappropriate speech subscales) in the resveratrol group were statistically similar to those in the placebo group. The repeated measures analysis showed no time × treatment interaction on these subscale scores. In contrast, patients in the resveratrol group showed greater decline in hyperactivity/non‐compliance score as a secondary outcome measure (mean difference [CI = 95%] = 4.51 [0.10‐8.92], t = 2.04; P = .04), and repeated measures analysis showed significant effect for time × treatment effect on this subscale score (F = 3.81; df = 1.30; P = .043). There was no significant difference in number and severity of adverse events between the two groups. What is new and conclusion This clinical trial demonstrated no significant effect for adjunctive treatment with resveratrol on irritability of patients with ASD. However, it provided preliminary evidence indicating that resveratrol could improve hyperactivity/non‐compliance of ASD patients.