Causes of dementia

Dementia is caused by a range of diseases and injuries that affect the brain, such as Alzheimer’s disease or vascular disease or head injury. In September 2021, the World Health Organisation (WHO) stated in their “Global status report on the public health response to dementia” that the number of people living with dementia is growing. They estimate that more than 55 million people are living with dementia, and this is predicted to rise to 78 million by 2030.

Informal care accounts for about half the global cost of dementia, and social care costs make up over a third.  Carers in high income countries like the UK know how these facts affect their daily lives.  Hidden costs are both financial and emotional. The WHO report describes how medication for dementia, hygiene products, assistive technology and household adjustments are more accessible in high income countries, with a greater level of financial support for the informal family carers who are involved.

The Director General of the WHO said, “The world is failing people with dementia, and that hurts all of us. Four years ago, governments agreed a clear set of targets to improve dementia care. But targets alone are not enough. We need concerted action to ensure that all people with dementia are able to live with the support and dignity they deserve.”

So how are we faring in the UK?

In May 2022 the Health and Social Care Secretary Sajid Javid announced a new 10-year plan to tackle dementia. The plan speaks of a boost of funding into research to better understand all neurodegenerative diseases.

The whole plan will not be published until later in 2022, but at the Alzheimer’s Society conference where he made this announcement, Mr Javid said that the new 10-year plan will focus on how “medicines and emerging science and technology” can be harnessed to improve outcomes for dementia patients across the country. In his speech he described dementia as the “leading cause of death” in England and Wales after COVID-19.

It’s always difficult to really get to the significance of what is meant when people describe dementia as a “leading cause of death”.  In the UK the doctors who attended the deceased during their last illness must provide a medical certificate of cause of death. This is what the family uses to register the death and is often known as a “death certificate.” It provides people with an explanation of how and why the person died. It’s the information from death certificates that gives rise to statements about what the leading cause of death might be in any population.  Those data shape government policy in health and social care.

The doctor must certify the cause of death “to the best of their knowledge and belief.”  It may not always be clear what the cause of death was. The immediate direct cause of death is recorded, but the doctor should also enter any other diseases, injuries, conditions, or events that contributed to the death.  Although the person may have died of bronchial pneumonia, it may have been caused by immobility and wasting because of Alzheimer’s disease. So, all three of these would be listed on the death certificate

The guidance for doctors says that they should almost never describe “old age” as the sole cause of death.  It may be a contributing factor.  The advice is that a degenerative condition such as Alzheimer’s disease should be given as the sole cause of death only if the mechanism by which it caused the death is unclear, but it is fully supported by the clinical history as the underlying cause.

As a result of increased levels of diagnosis, the number of people who die after it is known that they have dementia has increased massively in recent years.  If this is added to the increase prevalence of dementia due to the ageing population, of course the number of deaths recorded as caused by dementia will increase.  This increase in the awareness of dementia in the last decade is to be welcomed, even though, as the WHO has pointed out, there is still not enough effort being put in to support people to live in dignity.

But it must not be allowed to hide the fact that the incidence of dementia seems to have declined over the last 30 years.  In a study from the Harvard T.H. Chan School of Public Health, it has declined an average of 13% every decade in people of European ancestry living in the US or Europe.  The prevalence has increased because there is a larger pool of people who are at risk, but the incidence has decreased…. why?

It is hard to be sure, but in high income countries there is greater access to medicines that control the metabolic conditions like diabetes that increase risk, or ways of improving vascular health and blood pressure. Older people in their seventies now stayed longer in formal education than people who were in their seventies 30 years ago.  Every little counts.  Smoking cessation and rules around alcohol may be making a difference already.  Public health measures that protect against industrial accidents, head injuries and exposure to pollution may add to this. The recognition of dental health and hearing impairment as contributory factors supports policies of improved mouth care at every age, and provision of free hearing aids through the NHS.  Even the current awareness of the importance of sleep must be making some difference.

So, even though the bad news is that in many parts of the world there is not enough attention to dementia, the good news is that for many, health and social care policies and societal changes are making dementia less likely than it was for any individual who takes care of themselves.  But still there are forms of dementia that are inevitable because they are inherited.  In those cases, the person can live better for longer by paying attention to those lifestyle factors including diet and exercise, even if research has not found a cure.

We can look forward to the 10-year plan.  In the meantime, there are things we can all do to stay as well as possible.  But we should all be watching carefully to see whether there is sufficient commitment to supporting the informal carers who shoulder half the burden, and to funding the essential research that should be done on the “leading cause of death”.

Professor June Andrews


Professor June Andrews

Professor Andrews is a dementia specialist and former adviser to the Dementia Trust. After a long career in the NHS, academia and government, June now works as a consultant to Sedaca Ltd, making life better for people affected by dementia. She is the author of Dementia the One Stop Guide.

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