Hypermetabolism may be linked to neurodegenerative processes in ALS

Amyotrophic lateral sclerosis (ALS) is a disease of paradoxes. Patients usually have little or no medical history and tend to be fit and athletic,1 2 yet undergo a rapid, unrelenting decline. Patients predominantly present with progressive weakness, with involvement of cortical motor neurons and as the disease progresses, patients develop denervation, muscle atrophy, decreased muscle mass and decreased free fat mass, all of which would be expected to decrease energy expenditure.3 Yet patients with ALS are consistently hypermetabolic, with increased resting energy expenditure evident in up to 50% of patients.4

Several variables have been hypothesised to contribute to this hypermetabolic state, including uncontrolled fasciculations, increased respiratory work and mitochondrial dysfunction,4 yet the exact mechanism remains to be elucidated. In their JNNP paper Steyn and colleagues5 aim to …