June 27, 2014

Executive Functioning in Children and Adolescents with Multiple Sclerosis


Executive Functions (EF) include a range of superordinate abilities that control performance across many tasks allowing for cognitive efficiency and mental flexibility. Although EFs are commonly affected in MS, little is known about the EF components that are most affected, particularly in pediatric-onset MS patients. Ameeta Dudani, North York, ON, Canada, Rezwan Ghassemi, Sridar Narayanan, Douglas Arnold, Montreal, QC, Canada, John Sled, Brenda Banwell, Christine Till, Toronto, ON, Canada AAN Toronto 2010 [IN2-1.003]

The objective of this work was to evaluate the components of executive function (EF) that are impaired in pediatric multiple sclerosis (MS), and determine the clinical and neural correlates of impaired EF.

Participants included 32 MS patients (26 females) and 20 controls (17 females) group-matched for sex and age, with a mean age at assessment of 16.2 ±2.1 years for patients and 15.5 ±1.9 years for controls. EF components measured were attentional control / working memory, inhibition, cognitive flexibility, information processing, and behavioural manifestation of EF (as measured by parent-report on the BRIEF). Multiple linear regression analyses were performed to assess the correlation of impaired EF components with clinical (age of disease onset, disease duration, and total number of relapses) and neuroimaging (T1- and T2- weighted total brain lesion volume (LV), and T2 frontal lobe LV) variables, adjusting for age, sex, and IQ. Lesions were segmented using a fully automated, multi-spectral Bayesian technique, with manual correction where necessary.

Patients had a mean age of disease onset of 12.1 ± 3.7 years, average disease duration of 4.1 ± 3.2 years, and an average of 3.3 ± 2.1 relapses. Relative to controls, MS patients had significantly lower IQ (t=-3.63, p<.01), and performed significantly poorer on measures of information processing and cognitive flexibility. In MS patients, T2-weighted total brain and frontal lobe LV were significantly associated with all measures of EF, with adjusted r2 values ranging from 0.43 to 0.46 (p<.01 for all).

CONCLUSIONS / RELEVANCE: EF abilities are significantly reduced in pediatric MS patients compared with controls. Reductions in EF correlate with total brain and frontal lobe LV, which highlights the impact of inflammatory activity on MS-related executive dysfunction.

Supported by: The Canadian Institutes of Health Research (CIHR), The Multiple Sclerosis (MS) Society of Canada, and The Canadian MS Scientific Research Foundation.

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