Neuropsychological Functioning in Primary Dystonia: Updated and Expanded Multidomain Meta-Analysis

Area of Science:

• Neuroscience
• Cognitive Science
• Movement Disorders

Background:

• Primary dystonia, traditionally viewed as a motor disorder, is increasingly recognized for associated cognitive dysfunction.
• Emerging research suggests a broader impact of dystonia on cognitive functions.

Purpose of the Study:

• To conduct meta-analyses comparing cognitive measures in individuals with primary dystonia and healthy controls.
• To quantify the extent and nature of cognitive deficits in primary dystonia.

Main Methods:

• Systematic literature search across major databases (PubMed, Embase, Scopus, etc.) from January 2000 to October 2020.
• Meta-analysis using random-effects models with Hedge's g for effect size calculation.
• Assessment of heterogeneity and bias using Cochran's Q, I², and Egger's regression.

Main Results:

• A significant combined effect size (g = -0.56, P < 0.001) indicated lower cognitive performance in dystonia patients.
• Cognitive slowing was observed across multiple domains, including motor speed, nonmotor speed, executive functioning, and memory.
• Blepharospasm and inherited dystonia subtypes showed particularly worse cognitive performance.

Conclusions:

• Dystonia patients exhibit consistent, moderate-strength cognitive deficits across various neuropsychological tests.
• Cognitive slowing in dystonia extends beyond motor symptom effects, suggesting central nervous system involvement.
• Findings underscore the presence of multidomain cognitive difficulties in primary dystonia.