Assessing cognitive functioning in ALS: A focus on frontal lobe processes

Abstract

Objective: It is generally acknowledged that at least 50% of individuals with amyotrophic lateral sclerosis (ALS) will exhibit cognitive deficits outside of the characteristic motor neuron involvement. However, a specific cognitive profile has been difficult to ascertain due to disease-related testing barriers and limitations in the sensitivity and specificity of available assessment methods. This study assessed the level of functioning of extramotor frontal cognitive processes in ALS, and the amount of change in the functioning in these processes over time as disease progresses. Methods: Empirical tests validated for a model of frontal lobe functioning were modified into an assessment battery appropriate for individuals with ALS in a clinical setting (the ALS-CFB, Computerised Frontal Battery). Twenty ALS participants and 36 age- and education-matched neurologically healthy controls were tested, and a sub-sample of each group (11 ALS and 20 controls) re-tested after approximately nine months. Results and conclusions: Compared to standard neuropsychological screening tests that did not show a difference between ALS participants and healthy controls, the ALS-CFB illustrated a profile of extramotor frontal dysfunction involving energisation (preparing the neural system to respond) and executive functions, a profile that may be indicative of the nature of neurodegeneration in ALS.

Keywords:

• Amyotrophic lateral sclerosis
• frontal lobes
• cognition
• ALS-CFB
• longitudinal

Acknowledgments

We would like to especially thank the individuals with ALS who voluntarily contributed their time and efforts to this project. Thanks also to Liam Kaufman whose computerised paradigm to assess anti-saccades was modified for this protocol.

Declaration of interest

There were no industry sponsors involved in this research, and the authors do not have any disclosures to declare.

This research was funded by the ALS Society of Canada Bernice Ramsey Discovery Grant and by NIH-NDCD Grant #1R01DC009890-01A1. Additional funding was provided by the Brill Chair in Neurology, the Departments of Medicine at Sunnybrook and the University of Toronto, and the Sunnybrook Research Institute. Funding for genetic screening was provided the Canadian Consortium on Neurodegeneration in Aging.