The 6-month study, published in the peer-reviewed Journal of Autism Spectrum Disorders, administered L-carnitine to participants who ranged from 2 to 8 years old and measured outcomes using a yardstick called CARS (childhood autism rating scale). CARS is a 15-item scale which includes criteria such as communication (both verbal and nonverbal), object use, fear and nervousness and interpersonal relations. The scale was developed to identify autism as well as to quantitatively describe the severity of the disorder. The researchers concluded that the therapy significantly improved these scores in the subjects who received the supplementation.
The researchers, associated with the pharmacy and medical faculties at Ain Shams University in Cairo, noted that autism is a worldwide problem, with reported prevalances ranging from 6:1000 in Saudi Arabia, to 1:1000 in Israel, to 1:100 in the United States according to data from the Centers for Disease Control. Autistic patients, the researchers said, often have a normal lifespan. When taking this into account, they said, “in terms of the number of ‘patient years,’ ASD patients represent a patient population that is as large as that of Alzheimer’s disease, the current biggest neurological disorder. Despite the clear unmet medical need, currently, there is no recognized effective comprehensive treatment.”
Experts in the field believe that autism is influenced by a combination of genetic, environmental and immunological factors. New evidence has suggested that autistic patients show increased vulnerability to oxidative stress coupled with mitochondrial dysfunction.
Some autistic children showed evidence of mitochondrial dysfunction, the researchers said, which is confirmed by altered brain energy metabolism, lowered cellular energetic and deficient reserve mitochondrial energy capacity.
The double-blind, placebo-controlled study recruited 30 subjects, who ranged from 29 to 108 months old. They were randomly assigned to either a 16-member experiment or 14-member control group. The daily dosage was fixed at 100mg per kilogram of bodyweight per day, given in equal morning and evening doses in a glucose syrup. The materials were provided to study participants and dosing instructions explained by a clinical pharmacist.
The CARS test was administered by a single researcher who was unaware of whether subjects were members of the placebo or supplementation groups. The blood work and CARS evaluations were conducted at the outpatient pediatrics clinics at Ain Shams Univeristy Hospital.
Free and total carnitine blood levels were measured at 3 and 6 months using liquid chromatography mass spectrometry. The lab conducting these measurements was also blinded to the treatment status of the subjects.
Further studies needed
The researchers concluded that there was significant improvement in participants CARS scores (P-groups <0.001) and (P-overtime=0.006), with statistically significant differences in free carnitine levels (P = 0.027) and total carnitine levels(P = 0.036).There was no correlation between baseline free and total carnitine levels with changes in CARS scores from zero to 6 months (r > 0.5, P > 0.05). The L-carnitine therapy was generally well tolerated, the researchers said.
But, they noted, because there was no correlation between measured L-carnitine levels in the blood and the improvements in the CARS scores they could derive no blood or clinical predictors of patients who might be eligible for initiating L-carnitine therapy.
These results were consistent with positive outcomes in other recent studies of L-carnitine in the treatment of autism, which have shown improvement in some of the mental and physical manifestations of autism but not, generally, in the language usage impairments. The Egyptian researchers noted that their study did not elucidate a mechanism of action for the observed effects of L-carnitine, and they also said the dosage used was derived from earlier studies and may not be optimal. They recommended further studies to look into those factors.