Cognitive Impairment in Chinese Patients with Sporadic Amyotrophic Lateral Sclerosis

Abstract

Background: It has reached a consensus that patients with amyotrophic lateral sclerosis (ALS) could display cognitive impairment characterized by executive dysfunction or even dementia, but cognitive spectrum of Chinese patients with ALS still waits to be documented.

Methods: A total of 106 incident patients with sporadic ALS were enrolled and comprehensive neuropsychological tests covering memory, executive function, attention, language, and visuospatial function were administered to them. Neuropsychological performances of 76 age- and education- matched healthy controls were used for the purpose of classification and comparison.

Results: 106 patients were categorized into 4 subtypes:84 (79.2%) ALS with normal cognition (ALS-NC), 12 (11.3%) ALS with executive cognitive impairment (ALS-ECI), 5 (4.7%) ALS with non-executive cognitive impairment (ALS-NECI), and 5 (4.7%) ALS with frontotemporal lobe degeneration (ALS-FTLD). Under the same criteria, 2 (2.6%) and 1 (1.3%) healthy controls were diagnosed as ECI and NECI, respectively. The proportion of ECI was significantly higher in non-demented ALS than that in healthy controls, but it was not for NECI. Patients with ALS-FTLD had significantly severer bulbar function and older age than those with ALS-NC.

Conclusion: Comorbid FTLD occurred in around 5% of Chinese sporadic ALS cases. Different genetic background and unique age distribution of Chinese ALS patients might be the reasons for the relatively low rate of comorbid FTLD. Cognitive dysfunction, predominant but not exclusive in executive area, was present in around 16% of non-demented ALS patients.

Fig 1. Categorization of Chinese patients with sporadic ALS according to cognitive status (n = 106).

ALS, amyotrophic lateral sclerosis; ALS-ECI, ALS with executive cognitive impairment; ALS-FTLD, ALS with frontotemporal lobe degeneration; ALS-NC, ALS with normal cognition; ALS-NECI, ALS with non-executive cognitive impairment.

Fig 2. Age distribution of included ALS patients and the proportion of cognitive impairment and FTLD in each age group.

(A) Age distribution of included ALS patients. (B) Prevalence of cognitive impairment in each age group. ALS, amyotrophic lateral sclerosis; ALS-CI, ALS with cognitive impairment; ALS-FTLD, ALS with frontotemporal lobe degeneration.