This blog is part of the ‘Highlights from Perth’ collection of articles, where you can read about the content of some of the talks and posters presented at the 30th International Symposium on ALS/MND in Perth. Presentations have a code beginning with ‘C’ followed by a number (e.g. C50) to help locate the specific abstract in the official abstract book.
People with MND may experience difficulties with chewing and swallowing (dysphagia), problems with hand and arm control, reduced mobility and fatigue, which can make the effort of eating and drinking tiring. Dysphagia can affect around 85% of people with MND at some point throughout their disease progression. This is due to a weakening of the muscles in the mouth and throat, making it harder to eat and drink. Some people with MND choose to have a gastrostomy – a surgical opening through the abdomen into the stomach. This allows tube feeding – a way of passing specially prepared food and fluids straight into the stomach. Adapting nutritional intake and monitoring weight is important to help avoid unintentional weight loss that is associated with faster disease progression and shorter survival.
Loss of appetite
Session 8B opened with a presentation from Dr Fredrick Steyn (C95) who discussed some of the causes of weight loss including loss of appetite and hypermetabolism (increased rate of energy expenditure – although mobility may be limited, more calories are ‘burnt off’ than are consumed).
MND patients are more likely to be hypermetabolic, and those that are tend to have a faster disease progression with a risk of earlier death than those with a normal metabolism. However, no study definitively shows that hypermetabolism primarily contributes to weight loss in ALS (observed changes in body weight, BMI and % fat mass are comparable in hypermetabolic and normometabolic patients). Results showed that the appetite of people with MND decreased as the disease progressed, which correlated with weight loss. This raises several questions such as ‘Does loss of appetite also impact progression and survival?’ ‘What causes this loss of appetite?’ and ‘How can we intervene to recover appetite/stabilise weight?’. Loss of appetite in MND isn’t only due to bulbar dysfunction or physical disability, it could occur early in the disease with impairment of multiple mechanisms, such as the part of the brain that controls eating behaviour (Figure 1).
Using brain imaging and neuropsychological evaluation, a study which is due to be completed in January 2020, is investigating why/how people with MND lose their appetite and have increased metabolism. Understanding this in more detail could help slow down weight loss and disease progression, as well as potentially improving the quality of life of individuals with MND.
Watch Dr Steyn summarise the session in a video interview here.
Dietary intake
To maintain weight, energy intake must match the total energy expenditure. Dr Veronique Chachay (C96) discussed an observational study that was set out to determine whether people with MND and hypermetabolism consume more calories to offset their higher energy expenditure (as is recommended to prevent weight loss). Results found that both hypo- and hypermetabolic patients had a negative energy balance (their energy intake was too low to balance the high energy expenditure) – an exaggerated effect seen in hypermetabolic people. Despite this, people with MND should refer to dietitian care at diagnosis or with evidence of weight loss, independent of their onset site.
While it is encouraged to eat a higher calorie diet to increase/maintain weight, it may result in an intake of foods that are low in nutritional value (battered fish, pie, chips etc. rather than those that are rich in anti-oxidants). Effective guidelines or advice that help get around bulbar symptoms and weight loss would promote a diet that is realistic – nutritious foods that are also high in calories. Future directions could include precision nutrition whereby the timing and type of nutrition intervention would be tailored to patients’ individual needs and food preferences (e.g. taste preference, instead of high/low energy intake).
Swallowing exercises and EVOO
A pilot trial to assess the feasibility and effect of swallowing exercises and diet in people with MND was presented by Professor Victoria Flood (C97). The talk followed promising results from two trials. The first looked at moderate intensity aerobic exercises for strengthening muscle to support swallowing function. The second involved a mouse model to study diets with 20% of calories coming from extra virgin olive oil (EVOO).
Why EVOO? Associations are often seen between Mediterranean diets and a lower prevalence and incidence of other neurodegenerative diseases (Alzheimer’s Disease, Parkinson’s disease). EVOO is high in phenolic compounds which have protective anti-oxidative and anti-inflammatory effects. Within cells, the Golgi apparatus (a cell’s post office which functions to modify, sort and package proteins for secretion) is fragmented in MND causing impaired axonal transport. Studies on mice have shown EVOO to decrease stress markers, helpful for motor neuron function and survival.
In this preliminary study, participants were randomised into either undertaking swallowing exercises, an EVOO diet (3-4 tablespoons per day), or a combination of both. No improvements were seen in swallowing function for the exercise only OR diet only groups but a trend towards improved symptoms (e.g. less coughing with oral intake) and slightly increased weight was seen in the combined exercise and diet group. Early results suggest targeted exercise and diet are feasible and may improve swallowing function and weight status among some people. However, the study has some limitations and results need to be confirmed with more people, particularly targeting people soon after diagnosis or slower progressing.
PRISIM test to detect swallowing impairment
In the last presentation of the session, Dr Emily Plowman (C98) presented PRISIM (Physiologic Risk Index of Swallowing IMpairment), a standardised screening test to reliably identify markers of swallowing impairment in people with MND in clinics. Identifying swallowing impairment early and accurately could allow us to intervene and lead to positive outcomes such as extended survival. This simple tool can be used by any clinician and includes three quick clinical tests: a peak cough flow test, a validated patient report outcome (Eating Assessment Tool-10), and a swallow test with 90ml of liquid. PRISIM correctly classifies dysphagia status for 91 of every 100 patients examined, validating the tool to improve detection and care of dysphagia in MND.
Other resources:
- Check out the Nu (nutrition) and Sw (swallowing) tiles, as well as the other topics discussed at the Symposium, on our Periodic table of MND research.
- Webpage: Swallowing, Eating and Drinking
- MND Research Blog: Tackling weight loss in MND – from ProGas to PostGas
