The cerebellum in ALS: friend or foe?

Bede et al present an intriguing study of cerebellar degeneration in amyotrophic lateral sclerosis (ALS).1 The authors revisit a contentious facet of ALS to present novel insights into cerebellar pathology. ALS is primarily associated with motor cortex and pyramidal tract degeneration, but accompanying frontotemporal involvement is also commonly observed. Extrapyramidal and cerebellar involvement is less well characterised, despite compelling radiological and postmortem evidence.2 3 Positron emission tomography studies often detect hypermetabolic changes in the cerebellum, but the molecular underpinnings of these changes are not entirely clear and a variety of conflicting explanations have been offered. It has been repeatedly suggested …