Cognitive rehab tied to MRI changes in cognition-linked brain regions

Findings may help explain why rehab leads to gains for some MS patients

Lindsey Shapiro, PhD avatar

by Lindsey Shapiro, PhD |

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A researcher uses a flashlight to illuminate a gigantic brain while another scientist looks at it with a magnifying glass.

A three month cognitive rehabilitation program, with or without aerobic exercise, increased tissue volume and activity in brain regions linked to cognition among people with progressive forms of multiple sclerosis (MS), clinical trial data suggests.

The MRI findings offer potential biological explanations about why cognitive rehabilitation leads to cognitive gains for some MS patients, the researchers said in “Cognitive rehabilitation effects on grey matter volume and Go-NoGo activity in progressive multiple sclerosis: results from the CogEx trial,” which was published in the Journal of Neurology, Neurosurgery, & Psychiatry.

Cognitive impairment is common in MS and is thought to affect up to 65% of patients. But people with progressive types of MS often have more severe cognitive dysfunction than those with a relapsing-remitting disease course.

Both cognitive rehabilitation, involving activities to strengthen or restore cognitive abilities, and physical exercise have each been linked to cognitive improvements in MS patients, although their exact benefits are still being explored.

The CogEx trial (NCT03679468) examined the possible cognitive benefits of a combined cognitive rehabilitation and aerobic exercise approach among more than 300 people with progressive forms of MS, ages 25-65, who had existing impairments in information processing speed, a common type of cognitive issue in MS.

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Cognitive rehab’s effect on gray matter

The participants were randomly assigned to receive cognitive rehabilitation, aerobic exercise, cognitive rehabilitation with aerobic exercise, or neither, which they performed for 12 weeks and returned for another follow-up six months after stopping the intervention.

Cognitive rehabilitation involved computer-based brain tasks. In groups where cognitive rehabilitation wasn’t performed, patients performed a sham exercise involving basic internet searches/computer use. Aerobic exercise involved a step machine. The groups not assigned to aerobic exercise performed balance and stretching activities as a sham intervention.

The trial’s primary analysis showed that combining cognitive rehabilitation with aerobic exercise failed to improve cognitive performance relative to either intervention alone. A substantial number of patients did see improvements in information processing speed, however.

A subgroup of 104 participants also underwent MRI scans to look at changes in brain tissue volume and connectivity. The recent publication reports findings from that substudy.

Here, as in the broader study population, no differences were seen in cognitive performance between the different groups.

While most structural findings on MRI scans also didn’t differ by intervention, the volume of gray matter, which is brain tissue containing mainly nerve cell bodies, showed significant differences among the groups. These differences were largely driven by an increased gray matter volume over time in those who performed only cognitive rehabilitation.

Those who performed cognitive rehabilitation with or without aerobic exercise showed significant increases in gray matter volume across multiple brain regions relevant for cognition after 12 weeks. That contrasted with the groups that didn’t involve cognitive rehabilitation, where a general decrease in gray matter volume was observed. Gray matter is relevant for cognition and studies show its loss is associated with cognitive worsening in MS. For this reason, an increase “might be beneficial for cognitive performances,” the researchers said.

Indeed, in the groups performing cognitive rehabilitation, increased gray matter volume correlated with an improved performance in a test of verbal learning and memory.

Functional MRI scans were also performed to look at differences in brain activation and connectivity with the various interventions.

Cognitive rehabilitation was associated with increased activation of a brain region called the insula relative to groups that performed the sham computer activities at week 12. The insula is involved in attention and information processing, and its dysfunction has been linked to cognitive problems in MS.

While the study shows no “synergistic effect” of cognitive rehabilitation and aerobic exercise on cognitive performance or its MRI correlates, the findings do highlight that cognitive rehabilitation itself might lead to beneficial changes in brain regions linked to cognition that may explain cognitive improvements in some patients.

“Future studies exploring insular connectivity in this cohort may provide additional insights into changes taking place in the insular network post rehabilitation,” the researchers said.