Is MND/FTD the same as FTD alone?

Association-funded researcher, Prof Julie Snowden from the University of Manchester was invited to present her research on MND and frontotemporal dementia at this year’s 25th International Symposium on ALS/MND. She is asking whether people living with MND and frontotemporal dementia develop a different form of dementia that is different to those with frontotemporal dementia alone.

In 2011, when researchers discovered the C9orf72 inherited-MND gene, it was also linked to the related neurodegenerative disease frontotemporal dementia (find out more about inherited MND here). This increasingly recognised form of dementia has different signs and symptoms to the more common Alzheimer’s disease, but is less understood.

Researchers are now studying these previously separate diseases together. By working collaboratively with dementia researchers, we are beginning to understand this gene and the link between the two diseases. But what precisely is this link? In the past there were distinct disorders? Prof Snowden answered these questions as thinking of MND and FTD as a spectrum. 

Two of the same?

But, clinically is frontotemporal dementia (FTD), the same as MND with FTD? Prof Julie Snowden (University of Manchester) is hoping to answer this question.

Prof Snowden said: “Like MND, FTD is not a really nice neat disorder at all – it is very variable clinically, pathological and genetically.”

There is some evidence that those with MND and FTD develop a different balance of signs and symptoms to those with FTD only. Prof Snowden’s Association-funded research will conduct a study in patients and carers to determine if people with FTD and MND show more changes in the language and executive function aspects of FTD in comparison to greater change in behaviour and social cognition in people with FTD only.

Prof Snowden said: “We know that some people with MND develop a form of dementia, known as FTD, that affects behaviour and thinking. Our research aims to improve our understanding of the link between MND and FTD through a study of behaviour, thinking skills, and brain changes in people with MND/FTD and with FTD alone. 

“Our findings suggest that people with MND are not equally vulnerable to developing FTD, and there are differences between people with MND/FTD and with FTD alone. 

The differences

FTD is now very well recognised in relation to MND. Prof Snowden emphasised that in dementia clinics we are now seeing people with FTD develop signs of MND, and vice versa in MND care centres.

In terms of the differences, pathologically (by studying the brain tissue) there are three subtypes of TDP-43 pathology in pure FTD. Type A is characteristic by ‘cats eye inter-nuclear inclusions, type B has cytoplasmic inclusions, whereas type C has dystrophic neurites. Prof Snowden highlighted that in MND/FTD, all patients had type B pathology, which may help in the clinic as we can say that people living with FTD, which have type B may develop MND.

Unlike MND, the proportion of FTD cases that are inherited is up to 40%. Genetically C9orf72 accounts for the largest number of inherited FTD cases, and Prof Snowden said: “We see MND only associated with C9orf72 mutations, not TAU and progranulin mutations, showcasing that there are genetic differences between FTD alone and MND/FTD.”

“Another difference is that in MND/FTD there is a clear male preference compared to FTD alone, which is equal between sexes. Another important difference is that people with MND/FTD generally have an earlier age of onset than those with FTD alone.”

What’s next?

Prof Snowden’s Association-funded research, which began in October 2014, is investigating the differences between FTD and MND-FTD further. Prof Snowden said: “My research will hopefully lead to Early recognition of FTD in people with MND is crucial, because it affects people’s capacity to make decisions and adds to the burden on familities.

“We are very grateful for the MND Association to continue to support our future research into this area.”