Submitted and Edited by Francisco Gomez, MD
Cognitive inhibition impairments in presymptomatic C9orf72 carriers. Montembeault M, Sayah S, Rinaldi D, et al. Journal of Neurology, Neurosurgery & Psychiatry. Published Online First: 13 February 2020. doi: 10.1136/jnnp-2019-322242.
Nucleotide repeat expansions in the C9orf72 gene are a frequent cause of frontotemporal dementia and amyotrophic lateral sclerosis. Some authors have described cognitive dysfunction in C9orf72 patients preceding debut of motor symptoms related to ALS.
The authors sought to further elucidate relationships between cognitive impairment, motor symptomatology, and MRI findings. They included 38 C9orf72 patients younger than 40 years as well as 22 ALS controls.
Cognitive evaluation pertaining to cognitive inhibition was performed. Cognitive inhibition refers to the ability to resist interference from irrelevant stimuli while performing tasks, considered crucial to everyday living. The Hayling Sentence Completion Test (HSCT) is considered quite sensitive for said function and a predictor of everyday functioning and has been associated with frontal lesions on imaging. Thus, the authors propose early cognitive changes may be not only detectable via the HSCT but may also correlate with early MRI findings, which showed cerebellar volume loss in post-hoc volumetric analysis.
The authors found C9orf72 patients <40 years of age exhibited slower completion and increased errors in the HCST not seen in the control group. Furthermore, HCST completion times significantly predicted symptomatic debut. Notably, HCST completion time also correlated with cerebellar volume loss in post-hoc analysis further highlighting the involvement of the cerebellum in cognition.
Comments: Overall, the authors succeeded in integrating clinical testing with imaging findings in a novel way with direct clinical applications. HCST may offer a new tool for screening, evaluation and monitoring of C9orf72 patients. Early detection of symptoms may offer new avenues to patients, and may lead to earlier interventions, and we can now avail ourselves of a validated and easily performed test which can significantly predict symptomatic onset in their patients.