Motor Neurone Disease (MND), as the name suggests, is known as a disease of motor neurons, a specific type of neurons that co-ordinate our voluntary movement, leading to loss of the ability to move, speak and breathe. And perhaps because the main focus often falls on the rapidly-progressing physical symptoms and their management, the way MND affects the mind has often be overlooked.
Most literature on MND states that certain behavioural and cognitive (thinking) problems affect up to 50% people with MND, out of which 15% have a co-occurring diagnosis of frontotemporal dementia (FTD). Adding to this, a recent paper by Dr Christopher Crockford and colleagues, published in the journal Neurology, found that up to 80% of people living with MND will have some form of cognitive or behavioural impairment by the final stage of their disease (or in other words, only 20% will have an intact cognitive and behavioural processing).
The primary aim of the study was to explore the relationship between the different stages of ALS and the cognitive and behavioural changes that occur in people living with the disease. The research team collected data from 161 people with ALS, the most common form of MND, as well as from 80 people without the disease (controls) that were not related to the participants. The importance of testing the control participants is to exclude the possibility that the observed results are not caused by the effects of age, gender, location, years of education, or other factors including socioeconomic status, and anxiety and depression scores.
One of the crucial study measures was the King’s Clinical Staging System, which defines the stage of the disease primarily based on the bodily regions affected (i.e., upper limbs, lower limbs, or bulbar region), creating four stages of involvement, where only one region is affected in Stage 1, two regions in Stage 2, and three regions in Stage 3. Stage 4 is defined by nutritional and respiratory failure. The other measure of the study was the Edinburg Cognitive and Behavioural Screen (ECAS), which provides scores on the level of impairment of different components of cognition (including language, decision-making, memory and visuospatial functions), and assesses different domains of behaviour based on an interview with the participant’s caregiver.
By looking at the ECAS scores of people within each of the King’s Staging groups, the researchers found that ALS-specific cognitive and behavioural changes are associated with the different stages of disease progression, in so much as the further the disease progresses, the greater the cognitive/behavioural impairment is observed. Of the components that are most often associated with such cognitive change were letter fluency (ability to generate as many words as possible that begin with a specific letter in a restricted timeframe) and executive functioning (ability of decision-making, management and judgement). These findings can be further confirmed by previous neuroimaging studies that looked at the damage to neurons in the brain of people with ALS, which not only observed changes in the movement-related parts of the brain, but also in the parts not associated with motor function. Specifically, changes in the frontal and temporal regions (front and sides of the brain) are known to be involved in the control of executive function and language, suggesting that damage to these regions might therefore occur early on in the disease process.
Changes in behaviour were most evident in Stage 4, affecting 65% of participants. Some of the greatest changes were increase in apathy, disinhibition, loss of sympathy and presence of psychosis.
Why is this study important?
Findings of this study make an important point of the necessity of including cognitive and behavioural testing into routine ALS assessments tests, already suggested in the NICE guidelines on MND. It is also important to provide all people diagnosed with MND and their carers with information on the mind-related changes that are likely to occur throughout the course of the disease, and guidance on how to manage these. Enhanced support for carers might improve their quality of life and reduce carer burden by using more effective ways to communicate with people with a cognitive or behavioural impairment. It is also important to consider the effect any mind-related changes might have on end-of-life decisions.
For information on the way your mind might be affected in MND, see our Information Sheet 9A.
Commentary by Dr Paul Wicks & Dr Steven Albert: ‘It’s time to stop saying “the mind is unaffected” in ALS’.