This meta-analysis evaluated the effects of methylphenidate (MPH) on cognitive outcome and adverse events in adults with traumatic brain injuries (TBI). We searched PubMed, EMBASE, and PsycINFO for randomized controlled trials (RCTs) published before July 2019. Studies that compared the effects of MPH and placebos in adults with TBI were included. The primary outcome was cognitive function, while the secondary outcome was adverse events. Meta-regression and sensitivity analysis were conducted to evaluate heterogeneity. Seventeen RCTs were included for qualitative analysis, and ten RCTs were included for quantitative analysis. MPH significantly improved processing speed, measured by Choice Reaction Time (standardized mean difference (SMD): −0.806; 95% confidence interval (CI): −429 to −0.182, p
= 0.011) and Digit Symbol Coding Test (SMD: −0.653; 95% CI: −1.016 to −0.289, p
< 0.001). Meta-regression showed that the reaction time was inversely associated with the duration of MPH. MPH administration significantly increased heart rate (SMD: 0.553; 95% CI: 0.337 to 0.769, p
< 0.001), while systolic or diastolic blood pressure did not exhibit significant differences. Therefore, MPH elicited better processing speed in adults with TBI. However, MPH use could significantly increase heart rate. A larger study is required to evaluate the effect of dosage, age, or optimal timing on treatment of adults with TBI.
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