Pharmacological and dietary treatments for developmental stuttering: A systematic review

Pharmacological and dietary treatments are increasingly investigated as alternatives or adjuncts to behavioural therapy for developmental stuttering. However, their relative efficacy, acceptability, tolerability and safety remain unclear. This systematic review evaluated the evidence for these treatments.

We searched CENTRAL, MEDLINE, Embase, Cochrane and other databases from inception to June 2024 for studies examining pharmacological or dietary treatments for developmental stuttering. We did not limit studies by design. Primary outcomes included clinician-rated and self-reported measures of stuttering severity and frequency. Risk of bias was assessed using the Cochrane Risk-of-Bias tool (RoB 2) for randomised trials and ROBINS-I for non-randomised studies.

Thirty-nine studies examining 17 drug classes and 4 dietary treatments were included. Most studies (87 %) focused on adolescents/adults with persistent stuttering. Only 7 of 19 randomised controlled trials were rated as low/some risk of bias. Newer antipsychotics showed promising results with better tolerability than conventional antipsychotics. Atomoxetine combined with speech therapy showed greater stuttering reduction compared to speech therapy alone in children. Dietary treatments (copper, thiamine, green tea, Ayurvedic supplements) had insufficient evidence. Side effects varied widely, from minimal to severe enough to cause withdrawal, particularly with conventional antipsychotics.

Despite some promising findings, particularly for newer antipsychotics and atomoxetine, methodological limitations prevent definitive treatment recommendations. Key issues included lack of randomised placebo-controlled trials, inconsistent outcome measures, and small sample sizes. Future research requires larger trials with standardised protocols to evaluate treatment efficacy while accounting for individual variability in response and potential adverse effects.