To compare the extent of neurodegeneration between long-standing multiple sclerosis (MS), Parkinson’s disease (PD), amnestic mild cognitive impairment (aMCI), Alzheimer’s disease (AD) and healthy controls (HCs).

Total of 184 HCs, 112 MS, 37 PD, 34 aMCI, and 37 AD patients (age>45 years old) underwent 3T MRI scanning. Global and regional brain volumes including whole brain (WBV), white matter (WMV), gray matter (GMV), cortical (CV), deep gray matter (DGM) and nuclei-specific volumes of thalamus, caudate, putamen, globus pallidus, and hippocampus were derived with SIENAX and FIRST software. Analysis of covariance (ANCOVA) adjusted for age- and sex-differences compared the MRI-derived volumes. Post-hoc analyses of age- and sex-matched subjects were also conducted.

WBV was not significantly different between diseases. MS had significantly lower WMV compared to other disease groups (p<0.021). Only AD patients had smaller GMV and CV when compared to MS patients (both p<0.001). MS patients had lower thalamus volume when compared to all other neurodegenerative diseases (p<0.008). On the other hand, AD patients had smaller hippocampus volume when compared to the MS patients (p=0.034).

Long-standing MS patients exhibit lower WMV comparable to other neurodegenerative diseases and more thalamus damage compared to PD and aMCI.