title: The syndrome of cognitive impairment in amyotrophic lateral sclerosis: a population-based study.
abstract: BACKGROUND
  Despite considerable interest, the population-based frequency, clinical characteristics and natural history of cognitive impairment in amyotrophic lateral sclerosis (ALS) are not known.
  
  
  METHODS
  The authors undertook a prospective population-based study of cognitive function in 160 incident Irish ALS patients and 110 matched controls. Home-based visits were conducted to collect demographic and neuropsychological data. Patients were classified using the recently published consensus criteria and by a domain-based classification of both executive and non-executive cognitive processes.
  
  
  RESULTS
  13.8% of patients fulfilled the Neary criteria for frontotemporal dementia. In addition, 34.1% of ALS patients without evidence of dementia fulfilled the recently published consensus criteria for cognitive impairment. Non-demented ALS patients had a significantly higher frequency of impairment in language and memory domains compared to healthy controls. These deficits occurred primarily in patients with executive dysfunction. 14% of ALS patients had evidence of cognitive impairment without executive dysfunction, and no cognitive abnormality was detected in almost half the cohort (46.9%).
  
  
  CONCLUSIONS
  Co-morbid dementia occurs in approximately 14% of patients with a new diagnosis of ALS. Cognitive impairment, predominantly but not exclusively in the form executive dysfunction, is present in more than 40% of ALS patients who have no evidence of dementia. Cognitive impairment in ALS is not a universal feature, and its manifestations may be more heterogeneous than previously recognised.
authors.affiliation: Trinity College Institute of Neuroscience, Dublin, Ireland.
authors.forename: Julie
authors.initials: J
authors.lastname: Phukan
authors.forename: Marwa
authors.initials: M
authors.lastname: Elamin
authors.forename: Peter
authors.initials: P
authors.lastname: Bede
authors.forename: Norah
authors.initials: N
authors.lastname: Jordan
authors.forename: Laura
authors.initials: L
authors.lastname: Gallagher
authors.forename: Susan
authors.initials: S
authors.lastname: Byrne
authors.forename: Catherine
authors.initials: C
authors.lastname: Lynch
authors.forename: Niall
authors.initials: N
authors.lastname: Pender
authors.forename: Orla
authors.initials: O
authors.lastname: Hardiman
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000690:Amyotrophic Lateral Sclerosis / Q000150:complications*; D016022:Case-Control Studies; D003072:Cognition Disorders / Q000209:etiology*; D003704:Dementia / Q000209:etiology; D056344:Executive Function; D005260:Female; D057180:Frontotemporal Dementia / Q000209:etiology; D006801:Humans; D008297:Male; D008569:Memory Disorders / Q000209:etiology; D008875:Middle Aged; D009483:Neuropsychological Tests; D011446:Prospective Studies; D013577:Syndrome