Defining phenotypes of MS-related cognitive impairment

In a large and heterogeneous cohort of multiple sclerosis (MS) patients from Italy, 5 homogenous and clinically meaningful phenotypes of MS-related cognitive impairment were defined. These results can pave the way to future research on neuroanatomical substrates and help define tailored management strategies.

Cognitive impairment is a common and disabling feature of MS, affecting 40-70% of patients. Altering the behaviour and quality of life of MS patients, it can lead to social and personal difficulties, sometimes despite minimal concurrent physical disability. Information processing speed and episodic memory are the cognitive functions most frequently affected in MS, but additional difficulties in executive function, verbal fluency, and visuospatial abilities have been reported. MRI has proven to represent a powerful tool in investigating the neuroanatomy of cognitive impairment in MS patients, but a precise characterisation of cognitive phenotypes is still lacking.

In a study presented by Dr Ermelinda De Meo (Vita-Salute San Raffaele University, Italy), 1,212 clinically stable MS patients were compared with 196 healthy controls on a clinical, neuropsychological, and neuroanatomical level [1]. Based on the results, 5 cognitive phenotypes of MS were identified:

• preserved cognition in 19% of patients;
• mild verbal memory/semantic fluency in 30%;
• mild multi-domain involvement in 19%;
• severe attention/executive involvement in 14%; and
• severe multi-domain involvement in 18%.

Patients with a preserved cognition and/or mild-verbal memory/semantic fluency were on average younger and had shorter disease duration compared with individuals manifesting other phenotypes. Physical disability was lowest in patients with a preserved cognition and highest in patients with a severe multi-domain involvement. Severe cognitive phenotypes prevailed in progressive patients.

At MRI evaluation, reduced hippocampal volume was associated with mild verbal memory/semantic fluency, reduced cortical grey matter volume was associated with mild multi-domain involvement, higher T2-hyperintense lesion volume was associated with severe attention/executive involvement, and extensive brain damage was associated with severe multi-domain involvement.

1. De Meo E, et al. Identifying distinct cognitive phenotypes in multiple sclerosis. ECF 28^th Annual Meeting. Abstract 50.

Posted on 16 December 202016 December 2020