The unique impact of changes in normal appearing brain tissue on cognitive dysfunction in secondary progressive multiple sclerosis patients.

Objective: The purpose of this study was to examine the relationships between cognitive functioning, whole brain magnetic transfer ratio (MTR) imaging, supratentorial 1H-magnetic resonance spectroscopy imaging (1HMRSI), and conventional T1 and T2 imaging in a homogenous sample of SPMS patients.

Methods: Nineteen patients underwent a single 90-min imaging session that obtained T1-and T2-weighted images and MTR. 1HMRSI was obtained on 14 of these patients. Patients underwent a neuropsychological battery, which was used to create an integrated measure of cognitive impairment. Cognitive impairment was the dependent variable in two hierarchical multiple regression analyses in which T2 lesion load, T1 lesion load, and MTR or NAA/Cr were entered sequentially.

Results: MTR was significantly related to cognitive functioning (deltaR2 = 0.22, P = 0.02) after accounting for T2 lesion load (deltaR2 = 0.33, P = 0.01) and T1 lesion load (deltaR2 = 0.00, P = 0.98). NAA/Cr was not significantly related to cognitive functioning.

Conclusions: Cognitive dysfunction may act as a clinical marker of normal appearing brain tissue pathology in multiple sclerosis.