Using MRI to assess memory

Developing easy to perform routine MRI measurements as potential surrogates for cognitive impairment in MS.

Morrow SA, Menon S, Rosehart H, Sharma M.

Abstract

OBJECTIVES:

One of the most frequently disabling symptoms in Multiple Sclerosis (MS) is cognitive impairment which is often insidious in onset and therefore difficult to recognize in the early stages, for both persons with MS and clinicians. A biomarker that would help identify those at risk of cognitive impairment, or with only mild impairment, would be a useful tool for clinicians. Using MRI, already an integral tool in the diagnosis and monitoring of disease activity in MS, would be ideal. Thus, this study aimed to determine if simple measures on routine MRI could serve as potential biomarkers for cognitive impairment in MS.

PATIENTS AND METHODS:

We retrospectively identified 51 persons with MS who had a cognitive assessment and MRI within six months of the MRI. Simple linear measurements of the hippocampi, bifrontral and third ventricular width, bicaudate width and the anterior, mid and posterior corpus callosum were made. Pearson’s correlations examined the relationship between these MRI measures and cognitive tests, and MRI measures were compared in persons with MS who were either normal or cognitively impaired on objective cognitive tests using Analysis of Covariance (ANCOVA).

RESULTS:

Bicaudate span and third ventricular width were both negatively correlated, while corpus callosal measures were positive correlated with cognitive test performance. After controlling for potential confounders, bicaudate span was significant different on measures of immediate recall. Both anterior and posterior corpus collosal measure were significantly different on measures of verbal fluency, immediate recall and higher executive function; while the anterior corpus callosum was also significantly different on processing speed. The middle corpus collosal measure was significantly different on immediate recall and higher executive function.

CONCLUSION:

This study presents data demonstrating that simple to apply MRI measures of atrophy may serve as biomarkers for cognitive impairment in persons with MS. Further prospective studies are needed to validate these findings.

Figure: A) Hippocampal height B) Corpus callosum thickness C) Bicaudate width (2) D) Third ventricular width.

Memory loss and forgetfulness affects six out of ten PwMS. It often takes a back seat in MS care, but is responsible for a significant proportion of the morbidity reported (for example, performance at work, relationship difficulties and coping strategies). To date, the ability to assess this in the clinic has been limited by the strict reproducibility criteria only available in the context of research studies. Here, Morrow et al. report that it may be possible to do this on spot scans.

They report that corpus callosum thickness (see Figure), bicaudate span and third ventricular width measurements are most predictive of poor performance at memory and processing tests.

These findings make sense as the corpus callosum interconnects the two brain hemispheres, the caudate nuclei deal with verbal fluency and verbal learning/memory, while third ventricular width is a snapshot of brain volume loss occurring in the brain and is a predictor of memory and processing speed.

This then raises the question whether the MS world is ready to know this?

Sometimes it’s better not to know, at other times knowing is not enough.