Background: L-carnitine was proposed as a potential treatment for patients diagnosed with an autism spectrum disorder to improve mitochondrial dysfunction, but no prior randomized controlled trials have been conducted.
Material/Methods: Thirty subjects diagnosed with an ASD were randomly assigned to receive a standardized regimen (50 mg L-carnitine/kg bodyweight/day) of liquid L-carnitine (n=19) or placebo (n=11) for 3-months. Measures included changes in professionally completed Childhood Autism Rating Scale (CARS), hand muscle testing, and modified clinical global impression (CGI) forms; parent completed Autism Treatment Evaluation Checklist (ATEC), treatment adherence measurement (TAM), frequency and intensity of side effect rating (FISER)/global rating of side effect burden (GRSEB)/patient report of incidence of side effects (PRISE) forms; and lab testing.
Results: Significant improvements were observed in CARS (–2.03, 95% CI=–3.7 to –0.31), CGI (–0.69, 95% CI=–1.1 to –0.06), and ATEC scores. Significant correlations between changes in serum free-carnitine levels and positive clinical changes were observed for hand muscle strength (R2=0.23, P=0.046), cognitive scores (R2=0.27, P=0.019), and CARS scores (R2=0.20, P=0.047). Study subjects were protocol-compliant (average adherence was >85%) and generally well-tolerated the L-carnitine therapy given.
Conclusions: L-carnitine therapy (50 mg/kilogram-bodyweight/day) administered for 3-months significantly improved several clinical measurements of ASD severity, but subsequent studies are recommended.

Keywords: Double-Blind Method, Cohort Studies, Cognition - physiology, Child, Preschool, Child Development Disorders, Pervasive - physiopathology, Child, Carnitine - therapeutic use, Placebos