Researchers claim modern living may contribute to dementia

09 aug 2015--Researchers at the University of Bournemouth have published research using death statistics from a group of Western countries suggesting that more people are dying with neurological conditions now than twenty years ago, particularly among the over 75s. Rates in the US appeared to be growing faster than other US countries. In contrast, deaths from cancer and heart disease had dropped. The findings are published in the journal Surgical Neurology International.

The team, led by Prof Colin Pritchard, used World Health Organisation mortality data to study differences in death rates over twenty countries between 1989-1991 and 2008-2010. While cancer mortality and deaths from circulatory diseases fell over that time period, total neurological deaths – which include those caused by Alzheimer's and other dementias as well as motor neurone disease, Parkinson's disease and CJD – showed increasing trends across countries.

The numbers of deaths resulting from neurological diseases, per million people in the population, varied from country to country. However, there was an average rise of 2% across 20 Western countries in men aged 55-74 and a 1% rise in female deaths in this age group. In the UK, death rates actually fell over the twenty year period in this age group – by 14% in men and 12% in women. In contrast, US rates appeared to increase by 82% in men and 48% in women.

In the over 75's, there were larger increases in death rates across the countries studied, including the UK, with the US showing the largest increase across the 20-year period. The researchers claimed that the increases could be caused by 'modern living' but there was no investigation in the research paper as to the reasons behind the observed trends. There was also no breakdown in the paper of the particular neurological diseases that could have been behind the observed increases.

Dr Simon Ridley, Head of Research at Alzheimer's Research UK, said:

"Dementia is a condition coming increasingly under the spotlight both in terms of growing public awareness and the realisation for a need to better understand the diseases that cause it. There is certainly greater awareness of young-onset dementias but that does not necessarily reflect an underlying increase in prevalence. This study suggests there may have been a disproportionately high rise in deaths from neurological diseases in the US over the last 21 years compared to other countries, but the reasons for this observation aren't clear. Neurological diseases encompass a whole range of conditions from Alzheimer's and other dementias to motor neurone disease and CJD and it would be interesting to drill down to see which of these diseases may be increasing the most.

"Comparing death rates across multiple countries in a consistent fashion is challenging, and the trends could be influenced by many different factors across countries such as increasing diagnosis rates or changing health policy. We know that ageing is the biggest risk factor for dementia, so with a growing elderly population, we would expect more people to die with the condition. Despite this, a much higher rise in neurological deaths in the US compared to other Western countries suggests it may also be important to explore environmental influencers.

"We know that Alzheimer's and other dementias can have a complex interplay of risk factors, including age, lifestyle and genetics, and continued investment in research is vital to understand more about them. The findings that neurological deaths in the over 75s have increased in almost all 20 countries studied highlights the growing impact of these conditions on the population but we can't conclude that modern life is causing these conditions at a younger age."

More information: "Neurological deaths of American adults (55–74) and the over 75's by sex compared with 20 Western countries 1989–2010: Cause for concern." Surg Neurol Int 23-Jul-2015;6:123 Available from:surgicalneurologyint.com/surgicalint_articles/neurological-deaths-of-american-adults-55-74-and-the-over-75s-by-sex-compared-with-20-western-countries-1989-2010-cause-for-concern/ 

Provided by Alzheimer's Research UK