Age at Disease Onset Influences Gray Matter and White Matter Damage in Adult Multiple Sclerosis Patients (P4.137)

Objective: To explore the extent and distribution of brain gray matter (GM) atrophy and white matter (WM) microstructural abnormalities in adult multiple sclerosis (MS) patients according to their age at disease onset. Background: Age at disease onset may influence clinical status (level and time to reach fixed disability) during adulthood. Maturational effects and the presence of different pathophysiological mechanisms could contribute to explain clinical differences between pediatric and adult MS onset. Methods: High-resolution T1-weighted and diffusion tensor MRI scans were acquired from 58 pediatric-onset (PO) MS patients, 58 age-matched (AOA) and 58 disease duration-matched (AODD) adult-onset MS patients, and 58 healthy controls (HC). Between-group comparisons were adjusted for age or disease duration, as appropriate. Correlations with age at disease onset were analysed. Results: Compared to HC, MS patients had the expected patterns of regional GM atrophy and WM DT MRI abnormalities. Compared to PO-MS, AOA patient showed a reduced FA in the main supratentorial WM tracts (corpus callosum, cingulum, corona radiata, internal and external capsulae, posterior thalamic radiation), bilaterally. Compared to AODD, PO-MS had a reduced FA in the previous WM tracts. Compared to PO-MS, AOA patients had a widespread pattern of regional GM atrophy, whereas no difference was found between PO-MS and AODD patients. Conclusions: This multiparametric MRI study suggests that different pathological processes may operate in MS patients according to their age at disease onset. Compared to AOA, PO-MS patients have less extensive GM atrophy and less severe NAWM damage, suggesting that neurodegenerative and inflammatory-demyelinating processes could be less pronounced in these patients. However, with increasing disease duration, an accelerated NAWM damage seems to occur in these patients, which suggest an impaired reserve for structural plasticity over the long term. Partially supported by a grant from Italian Ministry of Health (GR-2009-1529671).