Global burden of neurological disease – Expert Q&A

A new analysis of global data shows neurological disorders like motor neuron, stroke, and Parkinson’s are the leading cause of disability worldwide.

International and local neurology experts will gather in Auckland this week for a summit on brain health to discuss new estimates on the global burden of these disorders. The summit coincides with the release of a series of papers in the Lancet Neurology on brain disorders, which the authors say should serve as a wake-up call for public health systems and research funding agencies.

Data has been pulled from the long-running Global Burden of Disease (GBD) study – which involves more than 3000 researchers, including New Zealanders and Australians.

The SMC asked a New Zealand expert who was involved in the research, to answer some questions ahead of Tuesday’s summit. 

Professor Valery Feigin, Professor of Neurology and Epidemiology, Director of the National Institute for Stroke and Applied Neurosciences of Auckland University of Technology

What’s the overarching theme of this research, and why was it done?

“The whole neurological community was waiting for these estimates for years because for the majority of countries these estimates were not available because there were no epidemiological studies of neurological disorders in these countries, and even fewer countries had data on the trends of some neurological disorders. Such estimates are absolutely crucial for evidence-based health care planning, resource allocation and priority setting for both practice and research. Now, for the first time, we have such estimates for 195 countries.”

What do you think are the most significant findings from this research for:

a) meningitis

“The GBD study provided estimates primarily for bacterial meningitis. These types of meningitis are largely preventable via vaccinations, yet the global burden of meningitis in terms of morbidity and mortality is large, especially in developing countries. Globally, the number of people with meningitis has increased from 2.5 million in 1990 to 2.8 million in 2016, with the largest burden observed in Sub-Saharan Africa. But even in developed countries, such as NZ, the burden of meningitis is considerable. In 2016, there were 257 cases of meningitis in NZ (this is two times more than in Australia, despite the difference in the population size) of whom 15 people died.”

b) motor neuron disease

“Although motor neuron disease is relatively rare disease, it is a disease with very high disability and mortality, with about 50 per cent of people dying within the first two years after the diagnosis. The GBD study showed large geographical variations in motor neuron disease, with the biggest burden in high income countries. It also found a large increase in the incidence of the disease from 1990 to 2016. Surprisingly, mortality rate from motor neuron disease in NZ was the highest in the world, and the reasons for that are not known.”

c) Parkinson’s 

“Parkinson’s disease was the fastest growing of all neurological disorders analysed in the GBD study. The number of individuals with Parkinson’s disease has more than doubled since 1990, increasing from 2.5 million that year to 6.1 million in 2016, and there are large geographical variations in the burden from this disease. If the current trend continues we can expect 12 million patients worldwide by around 2050. Although treatment of Parkinson’s disease is reasonably well established, there is an urgent need to develop new preventative strategies to curb the problem.”

d) migraine

“In contrast to the common perception that migraines are not a cause of substantial burden, the GBD study showed that the number of healthy life years lost due to migraines is the second largest among all diseases (second after low back pain). In 2016, over a billion of people suffered from migraine and, unlike many other neurological disorders, migraine rates do not decrease with socioeconomic developments, suggesting that their relative importance is likely to increase in the future.”

Is there a common trend across all these diseases in New Zealand – is their prevalence increasing/decreasing/stabilising and why?

“Almost one in two New Zealanders suffer from neurological disorders ranging from headaches and migraines to dementia and stroke, and the burden is increasing fast. All non-communicable neurological disorders in NZ have a common trend in increasing absolute number of people who suffer, die or remain disabled from these disorders. The main reason for that is ageing of the population and population growth. However, we also observe a very high (one of the highest in the world) and fast increasing prevalence of overweight/obesity and diabetes in NZ, which also are contributing factors to some of these disorders (e.g. stroke).”

Do we have the tools we need in New Zealand to tackle the problems these conditions bring and why/why not?

“The level and quality of health services (clinical care) for neurological disorders in NZ are one of the highest in the world. However, these services can be (and should be) improved. For example, our GBD estimates showed that instead of 36 full-time equivalent neurologists we currently have in our country we actually need 88 full-time equivalent neurologists. We also need more research funding to study neurological disorders, their causes and preventative strategies, ways to improve health care and outcomes.”

What should be the key take-home message from this research for New Zealand? 

“Given the size of the problem and a clear trend towards its increase, neurological disorders must be a priority area for health care development and research funding. We now have the best available estimates of incidence, prevalence, mortality and disability from the major neurological disorders in the country, therefore we have the foundation on which our health care policy makers can develop and prioritise health services for these disorders. Thus, there is no more excuse for health care policy makers not to act. They need to act urgently.”

How will this research affect global policy?
“The fact that neurological disorders are the leading cause of disability and the second leading cause of death worldwide, should place neurological disorders on the top priority lists for all governments.”