Multiple sclerosis is still regarded primarily as a disease of the white matter. However, recent evidence suggests that there may be significant involvement of gray matter. Here, we have used magnetic resonance imaging and magnetic resonance spectroscopy in vivo and histopathology postmortem to estimate thalamic neuronal loss in patients with multiple sclerosis. Our results show that neuronal loss in multiple sclerosis can be substantial (30-35% reduction). We conclude that a neurodegenerative pathology may make a major contribution to the genesis of symptoms in multiple sclerosis.

The longitudinal dynamics of the most promising biofluid biomarker candidates for Huntington’s disease (HD)—mutant huntingtin (mHTT) and neurofilament light (NfL)—are incompletely defined. Characterizing changes in these candidates during disease progression could increase our understanding of disease pathophysiology and help the identification of effective therapies. In an 80-participant cohort over 24 months, mHTT in cerebrospinal fluid (CSF), as well as NfL in CSF and blood, had distinct longitudinal trajectories in HD mutation carriers compared with controls. Baseline analyte values predicted clinical disease status, subsequent clinical progression, and brain atrophy, better than did the rate of change in analytes. Overall, NfL was a stronger monitoring and prognostic biomarker for HD than mHTT. Nonetheless, mHTT has prognostic value and might be a valuable pharmacodynamic marker for huntingtin-lowering trials.

Brain-derived neurotrophic factor (BDNF) is implicated in the survival of striatal neurons. BDNF function is reduced in Huntington’s disease (HD), possibly because mutant huntingtin impairs its cortico-striatal transport, contributing to striatal neurodegeneration. The BDNF trophic pathway is a therapeutic target, and blood BDNF has been suggested as a potential biomarker for HD, but BDNF has not been quantified in cerebrospinal fluid (CSF) in HD. We quantified BDNF in CSF and plasma in the HD-CSF cohort (20 pre-manifest and 40 manifest HD mutation carriers and 20 age and gender-matched controls) using conventional ELISAs and an ultra-sensitive immunoassay. BDNF concentration was below the limit of detection of the conventional ELISAs, raising doubt about previous CSF reports in neurodegeneration. Using the ultra-sensitive method, BDNF concentration was quantifiable in all samples but did not differ between controls and HD mutation carriers in CSF or plasma, was not associated with clinical scores or MRI brain volumetric measures, and had poor ability to discriminate controls from HD mutation carriers, and premanifest from manifest HD. We conclude that BDNF in CSF and plasma is unlikely to be a biomarker of HD progression and urge caution in interpreting studies where conventional ELISA was used to quantify CSF BDNF.

The longitudinal dynamics of the most promising biofluid biomarker candidates for Huntington's disease (HD) - mutant huntingtin (mHTT) and neurofilament light (NfL) - are incompletely defined, but could help understand the natural history of the disease and how these biomarkers might help in therapeutic development and the clinic. In an 80-participant cohort over 24 months, mHTT in cerebrospinal fluid (CSF), and NfL in CSF and blood, had distinct longitudinal trajectories in HD mutation carriers compared with controls. Baseline analyte values predicted clinical disease status and subsequent clinical progression and brain atrophy, better than did the rate of change in analytes. Overall NfL was a stronger monitoring and prognostic biomarker for HD than mHTT. Nonetheless, mHTT possesses prognostic value and is a valuable pharmacodynamic marker for huntingtin-lowering trials.