Towards a new understanding of social dysfunction in MND/ALS

Humans are essentially social beings. In everyday life, we regularly infer the thoughts, feelings, and intentions of others, an ability known as theory of mind. This unique aptitude to consider perspectives distinct from our own provides the foundation for a host of social interactions, enabling us to predict behaviour based on the mental states of others. Prominent theory of mind deficits are present in the behavioural variant of frontotemporal dementia (bvFTD), however, far less is known regarding this capacity in motor neurone disease (MND) or amyotrophic lateral sclerosis (ALS).

Overlap between MND/ALS and bvFTD is well established across clinical, neuropathological, and genetic levels. Despite this overlap, the status of social cognition in ALS has received relatively little attention.

A new study from researchers in Edinburgh, Scotland reveals that theory of mind is significantly altered in MND/ALS. The researchers asked the participants to make a judgment about the preference of a cartoon face. To successfully complete the task, participants had to choose the picture the eye gaze of the cartoon face was directed towards. Two aspects of theory of mind were investigated: (i) Cognitive or thinking e.g. ‘Which picture is Dina thinking of?’ and (ii) Affective or feeling e.g. ‘Which picture does Dina love?’.

A significant proportion of MND/ALS patients in the study were found to show impairments on both the cognitive and affective aspects of the theory of mind task. Interestingly, abnormal levels of apathy were present in 42% of those cases with an affective theory of mind impairment. The authors suggest that theory of mind disruption may contribute to the loss of insight and increased apathy that is a typical feature of behavioural variant FTD and can be seen in MND/ALS as well.

This study reveals important insights into the clinical presentation of MND/ALS by highlighting significant deficits in the ability to appreciate the thoughts and feelings of others. This reinforces its overlap with FTD where deficits of social cognition are felt to be central to many of the behavioural symptoms seen. Future research will serve to understand the relationship between theory of mind and social processes such as empathy to provide a comprehensive account of social functioning in this syndrome.

Reference:

van der Hulst E-J, Bak TH, Abrahams S. Impaired affective and cognitive theory of mind and behavioural change in amyotrophic lateral sclerosis. Journal of Neurology, Neurosurgery, and Psychiatry. 2014 Dec 4. [Epub ahead of print]

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