The syndrome of cognitive impairment in amyotrophic lateral sclerosis: a population-based study
- Julie Phukan1,
- Marwa Elamin1,
- Peter Bede1,
- Norah Jordan2,
- Laura Gallagher2,
- Susan Byrne1,
- Catherine Lynch1,
- Niall Pender2,
- Orla Hardiman1,3
- 1Trinity College Institute of Neuroscience, Dublin, Ireland
- 2Department of Neuropsychology, Beaumont Hospital, Dublin, Ireland
- 3Department of Neurology, Beaumont Hospital Dublin, Dublin, Ireland
- Correspondence to Dr Marwa Elamin, Trinity College Institute of Neuroscience, Dublin, Ireland;
Contributors Dr Julie Phukan contributed to the conception of the project and contributed to the process of data collection. Dr Marwa Elamin contributed to the process of data collection, analysed the data and wrote the manuscript, Dr Phukan and Dr Elamin have contributed equally to this manuscript. Dr Peter Bede contributed to the process of data collection and revised the intellectual content of the manuscript. Norah Jordan contributed to the process of data collection and revised the intellectual content of the manuscript. Laura Gallagher contributed to the process data collection and revised the intellectual content of the manuscript. Dr Susan Byrne revised the intellectual content of the manuscript. Catherine Lynch contributed to the conception and design of the study and to the process of data collection. Dr Niall Pender supervised the neuropsychological aspects of the study and revised the manuscript from a neuropsychological perspective. Professor Hardiman was responsible for the conception of the project, supervised all clinical aspects of the study in all stages of development and revised the manuscript from a clinical perspective.
- Received 31 March 2011
- Revised 3 June 2011
- Accepted 1 July 2011
- Published Online First 11 August 2011
Background Despite considerable interest, the population-based frequency, clinical characteristics and natural history of cognitive impairment in amyotrophic lateral sclerosis (ALS) are not known.
Methodology 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%).
Conclusion 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.
JP and ME are joint first authors of this paper.
Funding The research leading to these results has received funding from the Health Seventh Framework Programme (FP7/2007-2013) under grant agreement n° 259867, ALSA (the ALS Association), HRB (the Health Research Board, grant H01300) and Research Motor Neuron (previously named Motor Neuron Disease Research Foundation).
Competing interests None.
Patient consent Obtained.
Ethical approval Written informed consent was obtained from all participants. The study had full ethical approval from Beaumont Hospital Research Ethics Committee.
Provenance and peer review Not commissioned; externally peer reviewed.