When someone is diagnosed with motor neurone disease (MND), the focus understandably tends to fall on movement, muscle weakness, and gradual changes in physical function. There may also be changes in speech or swallowing. But MND can affect more than movement. Some people may also experience changes in thinking and behaviour, and these changes are important part of understanding the disease.
If you or someone you love is living with MND, knowing that thinking and behaviour can sometimes be affected can help you understand what may be happening, recognise changes if they occur, and seek the appropriate support early.
Can MND Affect Your Thinking?
The short answer is yes, it can but it doesn't always, and when it does, the degree varies enormously from person to person.
Research over the past two decades has reshaped our understanding of MND considerably. We now know that MND is not purely a disease of the motor system. Up to half of all people living with MND may experience some degree of cognitive or behavioural change, though for many, these shifts are subtle. They might notice difficulty finding the right word in conversation, or feel that planning and organising tasks has become harder than it used to be.
Some people find their concentration wanders more easily, or that they struggle with decisions that once felt straightforward.
These kinds of changes, sometimes referred to broadly as cognitive symptoms in MND, don't necessarily mean dementia. In many cases, they're mild and don't significantly interfere with daily life. They can, however, be confusing and sometimes distressing, particularly when they're unexpected.
Frontotemporal Dementia and MND: What's the Connection?
At the more significant end of the spectrum, a smaller proportion of people with MND roughly 10 to 15 per cent, according to MND Australia develop a condition known as frontotemporal dementia, or FTD. For many people the symptoms of dementia precede the motor symptoms, often by a number of years. The overlap between frontotemporal dementia and MND is now well established in the medical literature, and researchers understand that both conditions can involve degeneration in the frontal and temporal lobes of the brain.
FTD can bring more noticeable changes. A person might behave in ways that seem out of character; becoming unusually impulsive, losing interest in things they previously enjoyed, or showing less awareness of social cues. Some people develop a kind of emotional flatness, while others may become fixated on particular routines or foods. Language can be affected too, with some people finding it increasingly difficult to express complex ideas or follow involved conversations.
For families, these changes can be among the hardest aspects of MND to navigate. It can be deeply unsettling to see someone you love behave differently, and it sometimes creates tension or misunderstanding before people realise what's driving the changes. This is why awareness matters so much.
Not Everyone Is Affected
Many people with MND will never experience significant cognitive or behavioural changes. The disease affects everyone differently, and having MND does not mean dementia is inevitable.
Some people live with MND for years without any noticeable shifts in thinking or personality. Others might experience only very mild changes that don't progress. The range is wide, and there's no reliable way to predict at the point of diagnosis exactly who will be affected and to what degree.
What we do know is that early identification can make a real difference - not in changing the course of the disease, but in helping families understand what's happening and in making sure the right supports are in place. If you've noticed changes in yourself or someone you care for, raising them with your neurologist or MND care team is a worthwhile step.
What Can You Do?
Cognitive and behavioural assessments can be arranged through your general practitioner (GP), neurologist or multidisciplinary MND clinic. These assessments aren't about labelling anyone - they're about building a clearer picture so that care can be tailored to what you actually need.
For carers and family members, understanding that certain behaviours may be part of the disease can be genuinely relieving. It doesn't make it easy, but it can shift the way you respond, and it can ease some of the guilt or frustration that often accompanies these changes.
Multidisciplinary care teams, including neurologists, neuropsychologists, speech pathologists, social workers, and occupational therapists, play a vital role in supporting both the person with MND and their family through cognitive and behavioural changes. You don't have to figure this out alone.
For people living in NSW, ACT or the NT, MND NSW can help connect you with appropriate resources, guide you through what to expect, and provide emotional and practical support for the whole family.
What Else Could it Be?
There may be other causes of mild cognitive and behavioural change. Understanding recognising and responding to change is important to accessing the right support. Other factors may include difficultly managing strong emotions, medication side effects, fatigue, pain, discomfort, anxiety and depression.
In May 2024, Jason Smith shared his behavioural change story with us – read it here: Jason’s Story: Behavioural Change and MND
You're Not Alone in This
Living with MND can bring many changes and challenges. Greater awareness of the cognitive and behavioural changes that can occur can help families recognise these changes, access the right support when needed, and feel better supported throughout their journey.
If anything in this article has raised questions for you, please reach out to your MND care team. They're there to help, and so are we: https://www.mndnsw.org.au/contact-us.html
Want to learn more?
To learn more about MND and FTD, visit the MND Hub and explore our online MND 101: An Introduction to Motor Neurone Disease (MND) course.
This article is for informational and educational purposes only. It is not intended as medical advice, diagnosis, or treatment. If you have concerns about cognitive or behavioural changes related to MND, please speak with your neurologist, GP, or MND multidisciplinary care team for guidance tailored to your individual circumstances.
