Exercise Study of Function and Pathology for Women With X-linked Adrenoleukodystrophy

X-linked adrenoleukodystrophy (X-ALD), a [sex-linked] progressive neurodegenerative disease, is caused by a defect in the ABCD1 gene. The disease is expressed in multiple ways, but the most common adult form is adrenomyeloneuropathy (AMN), which results in slowly progressive changes in muscle tone and weakness, sensory loss, and dysfunction of the autonomic nervous system. In a previous study the investigators linked abnormalities in the [brain/spinal cord] to lower extremity weakness in men with AMN; however, there have been no studies evaluating these relationships in women carriers (i.e., women with AMN). It is unknown, in women with AMN, how the pattern of damage in the brain and spinal cord relates to disability and if these patterns predict responsiveness to treatment. The investigators hypothesize that by using magnetization transfer (MT) and diffusion tensor imaging (DTI), two magnetic resonance imaging (MRI) modalities, to track particular changes in the brain and spinal cord will predict disability and additionally, who is likely to respond best to a training regimen. The investigators expect that these more advanced imaging techniques will be more sensitive and accurate quantitative measures of clinical motor function and women with greater loss in the spinal cord compared to the brain will benefit most from training to improve disability. To test this hypothesis, women with AMN will receive MRI scans at baseline and complete measures of global walking and lower extremity impairments of vibration sensation, spasticity, and strength at three time-points: baseline, 12 weeks, and 18 weeks after baseline. The group will participate in a resistive training program for 12 weeks. MRI data will be correlated to changes over time in measures of impairment to determine their relationships. The linking of this information will not only be important for better defining disability in women with AMN but it will also help to guide physicians and rehabilitation therapists in predicting who is likely to respond to rehabilitative interventions, as well as for optimizing the effects of future pharmacological interventions.

Inclusion criteria

• confirmed diagnosis, X-ALD heterozygote carrier
• no medical contraindication to participating in a strength training program
• able to follow complex directions as determined by a score of ≤1 on a subset of questions taken from the NIH Stroke scale (Brott et al. 1989)
• hip flexion strength: 6.6-15.8kg
• hip extension strength: up to 18.3 kg
• normal passive range of motion at hips/knees/ankles
• able to walk ≥50m

Exclusion criteria

• Evidence of other neurological deficit that could interfere, such as previous stroke or muscle disease
• congestive heart failure
• cancer
• orthopedic conditions
• severe pain that precludes study participation
• seizures
• pregnancy
• other medical condition that precludes participation in an exercise program, e.g., unstable angina, uncontrolled diabetes, uncontrolled hypertension

Healthy controls have the same age and exclusion criteria as women with AMN except that they will not be carriers for X-ALD. They must have normal neurological function.