Frontotemporal dementia and motor neuron disease

Today Jenny Saxon (@jennie_saxon) gives us some insights into fronto-temporal dementia and motor neuron disease. Any questions, drop her a tweet! – The #demphd team (Julie, Paul, Grant, Clarissa) 🙂

Fronto-temporal dementia (FTD) is one of a set of syndromes resulting from progressive degeneration of the frontal and temporal lobes of the brain. Sometimes called behavioural variant FTD (bvFTD), the primary presenting symptoms are usually striking changes in personality and behaviour. People with bvFTD show a wide range of different behaviours, but a few features that are reported commonly are:

  • Social disinhibition (e.g., doing or saying embarrassing things in public, or acting impulsively)
  • A reduction in motivation, or performing little purposeful activity
  • Changes in behaviour towards their loved ones – in particular seeming to care less and show less sympathy
  • A tendency to do or say the same things repeatedly, or follow a particular routine in an obsessive manner
  • Changes in eating behaviour, such as showing a preference for a particular type of food (often sweets) or overeating indiscriminately

As well as changes in behaviour, people with FTD usually show some changes on neuropsychological testing. Particularly common are changes in executive function, which can be thought of as the ‘management system’ of the brain, responsible for a number of functions such as planning and organisation, attention, inhibition and reasoning. People also often show changes in social cognition – the way we interpret social cues (e.g. recognising emotions or judging the thoughts of others).

It has been known for a while that some people who have FTD also develop another condition, called motor neuron disease (MND). This is a rapidly progressive, fatal condition which results in changes to the muscles – weakness, wasting, and small twitches known as fasciculations. About 15% of FTD patients develop MND, and about 10% of MND patients go on to develop FTD, although many more (up to 50%) may have some milder degree of cognitive change (Ringholz et al. , 2005). Although we know the two diseases are connected, there is still a lot to learn about FTD with MND. It has generally been assumed that the behavioural and cognitive changes are the same in both FTD and FTD-MND. However, some research including people with cognitive change in MND suggests that people may have difficulties with language, a change not typically seen in ‘pure’ FTD (Taylor et al. , 2013). More recent work which has looked at language in FTD-MND (specifically at syntactic comprehension) has confirmed that there are features which are not entirely typical for FTD alone (Kamminga et al. , 2016). However, few direct comparisons have been made between FTD and FTD-MND, and none have attempted to describe a full behavioural and cognitive profile.

My PhD work, funded by the Motor Neuron Disease Association, compares these two groups in detail. A full cognitive assessment is carried out, with detailed assessments of different aspects of language, memory, social cognition, visuospatial function, praxis and executive function. I am also measuring behavioural changes, using participants’ own views, the views of their relatives /carers, and observations made during the cognitive assessment.

If these comparisons show differences in how these groups perform on these tests, this would be helpful in a number of ways. It would mean that clinicians could potentially identify people with FTD who were likely to develop MND in the future and ensure management is planned accordingly. Similarly, with an accurate understanding of its clinical presentation, developing FTD in people with MND could be identified quickly. This is vital, because people with MND are required to make decisions about their care and it would be important to know if they have difficulties in understanding, reasoning and decision making. There are also implications for future treatment: FTD can be caused by several different underlying proteins in the brain, but FTD-MND is almost always caused by the same protein (TDP-43 type B). As treatments are developed, it will be increasingly important to be able to predict the underlying causes of disease in order to target therapies accordingly.

Jennie

 

 

References

Ringholz GM, Appel SH, Bradshaw M, Cooke NA, Mosnik DM, Schulz PE. Prevalence and patterns of cognitive impairment in sporadic ALS. Neurology. 2005 Aug 23;65(4):586-90.

Taylor LJ, Brown RG, Tsermentseli S, Al-Chalabi A, Shaw CE, Ellis CM, et al. Is language impairment more common than executive dysfunction in amyotrophic lateral sclerosis? J Neurol Neurosurg Psychiatry. 2013 May;84(5):494-8.

Kamminga J, Leslie FVC, Hsieh S, Caga J, Mioshi E, Hornberger M, et al. Syntactic comprehension deficits across the FTD-ALS continuum. Neurobiology of Aging. 2016;41:11-8.

 

Published by Clarissa Giebel (@ClarissaGiebel)
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