The following is a summary of “Neurocognitive performance in functional neurological disorder: A systematic review and meta-analysis,” published in the July 2024 issue of Neurology by Millman et al.

Despite frequent reports of cognitive troubles in functional neurological disorder (FND), a debate on whether this translates to measurable cognitive decline.

Researchers conducted a retrospective study to analyze performance on validated cognitive tests in patients with FND across various cognitive domains.

They searched Embase, PsycInfo, and MEDLINE (15 May 2023), using terms for FND and cognitive domains (e.g., attention, memory, executive functioning). Studies included various FND phenotypes (seizures, motor, mental disorder, mixed) and compared them to healthy or clinical controls. The risk of bias with the modified Newcastle–Ottawa Scale was assessed, and a qualitative synthesis/narrative review of cognitive performance in FND was conducted. Test performance scores were taken out, and random effects meta-analyses were performed where appropriate.

The results showed 56 studies, including 2,260 individuals with FND. Although some impairments were noted across executive functioning, attention, memory, and psychomotor/processing speed, inconsistencies appeared among studies and FND phenotypes. Common confounds contained group differences in demographics, medication, and intellectual functioning. Only 24% of studies objectively showed performance validity. Meta-analyses showed higher scores on tests of naming (g = 0.67, 95% CI 0.50, 0.84) and long-term memory (g = 0.43, 95% CI 0.13, 0.74) in functional seizures vs. epilepsy, but no significant differences in working memory (g = −0.08, 95% CI −0.44, 0.29), immediate memory (g = 0.25, 95% CI −0.02, 0.53), and cognitive flexibility (g = −0.01, 95% CI −0.29, 0.28).

Investigators concluded that the evidence for objective cognitive deficits in FND was mixed, calling for future research with stricter controls and assessments of objective and subjective cognitive function.

Source: onlinelibrary.wiley.com/doi/full/10.1111/ene.16386