Study Highlights Cognitive Challenges Among Patients With POMS

Individuals with pediatric-onset multiple sclerosis (POMS) exhibited reduced episodic memory performance when compared with healthy controls (HC), while aspects of episodic memory performance were associated with hippocampal and thalamic volume, research published in NeuroImage: Clinical revealed.

“Children and adolescents with MS are particularly vulnerable to cognitive and psychosocial impairment given that the neuropathological processes involved in MS disrupt primary central nervous system myelination and compromise cortical, white matter, and subcortical structural integrity,” researchers explained.

Some previous studies have revealed the hippocampus was smaller in individuals with POMS. In addition, in adults with MS, reduced amygdala volume has previously been associated with impaired social cognition. The relationship between emotional processing and MS is unclear and past investigations have yielded mixed results.

To assess whether individuals with POMS differed from matched controls with regard to accuracy and response time (RT) Penn Computerized Neurocognitive Battery (PCNB) measures of episodic memory and emotion identification, and regional brain volumes of the hippocampus, amygdala, and thalamus, researchers carried out a cross-sectional analysis.

Data were gleaned from the Canadian Pediatric Demyelinating Study, a longitudinal study including 23 sites across Canada and the Children’s Hospital of Philadelphia.

All participants (n = 65) had a confirmed diagnosis of POMS, and a mean (SD) age of 18.3 (3.9) years. The majority of patients were female (73.8%) while average disease duration was 3.8 (3.8) years. Seventy-six age-matched HCs were also included.

Patients and HCs completed the PCNB and analyses were conducted on episodic memory, emotion identification, and composite domain scores. “The 3 subtests in the episodic memory domain include: Word Memory, Object Memory, and Face Memory. The 3 subtests in the emotion identification domain include: Age Differentiation, Emotion Identification, and Emotion Differentiation,” authors wrote.

Fifty-nine individuals with POMS and 69 HCs also completed 3T magnetic resonance imaging (MRI) scanning.

Analyses revealed:

• POMS participants were both less accurate (P < .01) and slower (P = .05) than HCs on the episodic memory domain, after controlling for covariates
• POMS participants showed reduced accuracy on word memory (P = .002) and slower performance on face memory (P = .04) subtests
• POMS participants had smaller total and regional brain volumes of the hippocampus, amygdala, and thalamus (P ≤ .01)
• Collapsing across groups, both hippocampal and thalamic volume were significant predictors of word memory accuracy
• Hippocampal volume (B = 0.24; SE = 0.10; P = .02) was more strongly associated with word memory performance than thalamic volume (B = 0.16; SE = 0.05; P = .003), though the estimate with was less precise.

Overall, individuals with POMS exhibited reduced accuracy on a test of verbal recognition and were slower to recognize faces compared with HCs. Patients also had smaller normalized thalamic volume compared with controls “and this effect was most robust relative to other brain regions examined in our study,” researchers said.

The PCNB only assessed recognition and not recall memory, marking a limitation to the study. Because the tests included may have been too simple, authors also cannot conclude emotional identification abilities are unaffected in patients with POMS.

Reference:

Fabri TL, Datta R, O’Mahony J, et al. Memory, processing of emotional stimuli, and volume of limbic structures in pediatric-onset multiple sclerosis. Neuroimage Clin. Published online July 9, 2021. doi:10.1016/j.nicl.2021.102753