ABSTRACT
Patients with neuromuscular disorders very often have disabling conditions that
may interfere with everyday activities. The disabilities caused by a neuromuscular
disorder may affect mood: depression and anxiety may develop. These symptoms
are often a reactive response to the underlying medical condition and are usually
not considered part of the neuromuscular disorder. There are, however, a number
of neuromuscular disorders in which behavioral and cognitive studies have
demonstrated a selective impairment of brain function. This may be the result
of the absence or deficiency of a membrane structural protein (like dystrophin)
present in brain and muscle or of a ubiquitous protein kinase (like that involved
in myotonic dystrophy type 1 or Steinert’s disease). Alternatively, tissues like
brain, in which oxidative metabolism is very active, may be affected just like
muscle in the mitochondrial encephalomyopathies. Channelopathies may
involve muscle and nerve, but also brain function if the ion channels responsible
for the neuromuscular symptoms are present in brain neurons. There is growing
evidence that clinical manifestations of amyotrophic lateral sclerosis (ALS) can
include a frontotemporal dementia, which may correlate with the extent of
ubiquitin-immunoreactive intraneural inclusions in cortical regions (Table 1).
