Dementia and mild cognitive impairment in amyotrophic lateral sclerosis: A review
TSERMENTSLI S., PhD

Amyotrophic Lateral Sclerosis (ALS) is a terminal neurodegenerative disorder which causes muscle wasting throughout the body. For many years, ALS was thought to affect only the body, with the mind and senses remaining intact. Indeed, much of the patient literature and information in medical textbooks continues to promote this myth. Recent evidence however suggests that ALS is a multisystem disorder with a varying presentation and with widespread extra-motor involvement. The current review sets out to provide a summary of what is known about the cognitive consequences of this neurodegenerative disorder.

Support for a concept of ALS as a multisystem disorder has some basis in reports that have highlighted the existence of frontotemporal dementia in at least a small percentage of ALS patients. A larger subgroup of ALS patients however show mild deficits on 'executive' tasks of frontal lobe function such as verbal fluency or set shifting, whereas abnormalities in language and memory are rare but increasingly reported. Patients may present with cognitive deficits before, after, or at the onset of ALS. Neuroimaging studies have also shown extra-motor cortical degeneration corresponding to levels of frontal executive impairment on neuropsychological testing. The potential clinical and theoretical implications of cognitive impairment in ALS patients will be discussed. Understanding of this condition will lead to better care for patients and provide valuable insights into the pathogenesis of neurodegeneration. Encephalos 2010, 47(1):10-17.

Key words: Amyotrophic lateral sclerosis, dementia, cognitive impairment.