Forty-four studies (n=1,336) were included: 33 placebo-controlled, double-blind crossover trials (29 of which were randomised), 6 parallel-design studies (4 of which were double-blind) and 5 cross-sectional studies. The sample sizes varied from 8 to 180 participants.
Benzodiazepines: 35 studies, 33 of which were carried out in healthy individuals, showed varying effects of different doses of lorazepam, diazepam, brotizolam, nitrazepam, lormetazepam, tiazolam and chlordiazepoxide. The effects varied with dose and time of testing relative to the dose, but were commonly associated with adverse outcomes for tracking and reaction time. Further details were reported.
Newer non-benzodiazepine hypnotics: 6 studies, including five of 7.5 mg zopiclone and five of different doses of zolpidem, found varying effects on numerous different outcomes. The effects varied according to the time of testing relative to the dose. Further details were reported.
Antidepressants and anxiolytics: 4 studies reported on 50 mg amitriptyline (3 studies), 50 mg trazodone (1 study), 40 mg fluoxetine (1 study), 30 mg paroxetine (1 study), 20 mg mirtazapine (1 study) and 20 mg buspirone (1 study). Few adverse effects on reaction time were reported, and those that were did not appear to be long lasting. Further details were reported.
Lithium: 4 studies reported data on lithium. One study was in healthy controls, two in patients with mood disorders, and one RCT in patients with Meniere’s disease. The effects varied and were generally adverse, with the exception of patients with Meniere’s disease, where reaction time and speed were not affected by lithium after 6 months of treatment. Further details were reported.
Antipsychotics: 5 studies in healthy individuals assessed the effects of 50 or 200 mg amisulpride, 50 mg chlorpromazine, 25 mg thioridazine, 0.5 mg haloperidol and 0.5 mg flupenthixole. In general, the studies reported no differences in reaction time, tracking errors and mistakes. One study assessed the effects of flupenthixole and fluphenazine (doses not stated) in patients with schizophrenia. This reported longer reaction times and worse driving accuracy in comparison with control groups. One study also suggested that adverse effects were worse with typical antipsychotics than with atypical antipsychotics. Further details were reported.