Friedreich ataxia is a rare progressive condition that causes damage to the nervous system. It is inherited in an autosomal recessive pattern, meaning that an affected gene must be inherited from each parent for the disease to develop in their child. It is the most common recessively inherited ataxia worldwide. It usually presents between the ages of 5 and 15 years with clumsiness of movement, progressing to unsteadiness in standing and walking. Speech usually becomes slurred. Most people with the condition become wheelchair-dependent in their late teens or early twenties. Heart abnormalities cause premature death in 60% to 80% of people with the disorder. Other significant problems which may develop include scoliosis (curvature of the spine), and pes cavus (high arched foot deformity). The progression of the disease cannot be easily assessed by clinical examination or a laboratory test. Evaluation of disease progress using standard neurological scales is made more difficult when the person is wheelchair-dependent.
Recent studies have suggested that a synthetic antioxidant idebenone may help the most frequent heart abnormality, enlargement of the left ventricle. Antioxidants occur naturally in foods but do not reach a level that would be considered necessary to alter the progress of Friedreich ataxia.
A review of the medical literature revealed one small randomised controlled trial with 29 participants that used idebenone for a sufficient period, 12 months, and the review authors identified no new studies when the searches were updated in 2011. Randomised controlled trials are studies in which people are allocated at random to receive one of several clinical interventions. One of these interventions is a control. The control may be a standard practice, a placebo (for example a sugar coated pill) or no intervention at all. Randomised controlled trials are generally accepted as the most valid method of determining the efficacy of a treatment, because the biases associated with other experimental designs can be avoided.
The included randomised controlled trial showed that idebenone did not help the neurological symptoms associated with Friedreich ataxia. We considered it at low risk of bias on five of the seven criteria assessed. Idebenone showed a positive effect on heart muscle but the clinical relevance of this change was not assessed in the study. There were no adverse events.