Implications of structural and functional brain changes in amyotrophic lateral sclerosis

ABSTRACT

Introduction: Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease that causes progressive muscle weakness and disability, eventually leading to death. Heterogeneity of disease has become a major barrier to understanding key clinical questions such as prognosis and disease spread, and has disadvantaged clinical trials in search of therapeutic intervention. Patterns of disease have been explored through recent advances in neuroimaging, elucidating structural, molecular and functional changes. Unique brain signatures have emerged that have lent a greater understanding of critical disease mechanisms, offering opportunities to improve diagnosis, guide prognosis, and establish candidate biomarkers to direct future therapeutic strategies.

Areas covered: This review explores patterns of cortical and subcortical change in ALS through advanced neuroimaging techniques and discusses the implications of these findings.

Expert commentary: Cortical and subcortical signatures and patterns of atrophy are now consistently recognised, providing important pathophysiological insight into this heterogenous disease. The spread of cortical change, particularly involving frontotemporal networks, correlates with cognitive impairment and poorer prognosis. Cortical differences are also evident between ALS phenotypes and genotypes, which may partly explain the heterogeneity of prognosis. Ultimately, multimodal approaches with larger cohorts will be needed to provide sensitive biomarkers of disease spread at the level of the individual patient.

KEYWORDS:

• Amyotrophic lateral sclerosis
• cortical patterns
• cortical thickness
• diffusion tensor imaging
• functional imaging
• magnetic resonance imaging
• positron emission tomography

Declaration of interest

Professor Matthew Kiernan serves as Editor-in-Chief of Journal of Neurology, Neurosurgery, and Psychiatry. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Additional information

Funding

This paper was supported by funding to Forefront from the National Health and Medical Research Council of Australia Program Grant (Grant No: 1037746). T Dharmadasa is a recipient of an Australia Postgraduate Award (University of Sydney), Rotary Club of Cronulla Funding Partner Scholarship, MNDRIA PhD Top-Up Scholarship, and the Yulgilbar Alzheimer’s Research Program PhD Top-Up Award. W Huynh was supported by the University of Sydney post-doctoral fellowship award.