Regular readers may remember our previous posts discussing the future of various medical conditions: in November last year, we explored how common diabetes, heart disease, HIV, malaria and hepatitis might be in coming decades; and in February earlier this year, we examined predictions for allergies, asthma, arthritis, psoriasis and osteoporosis.

In our third post on the subject, we’ll be trying to weigh up the future of two age-related conditions: dementia and visual impairment.

As before, we’ll take into account available data on recent trends, possible instigating factors behind a rise or decline in prevalence, and how experts think treatment may evolve in the coming years.

How common will dementia be in 2050?

Last year, dementia overtook heart disease as the leading cause of death in England and Wales. The Office for National Statistics reported that in 2015, 11.6% of all registered deaths were caused by dementia or Alzheimer's; whereas ischaemic heart disease was the cause of 11.5%.

This, according to statistician Elizabeth McLaren, was partly due to a change in rules in determining cause of death (leading to an increase in dementia being identified as an underlying cause) but also due to the fact that detection rates have improved, and that people are living for longer.

As a result of the projected rise in the ageing population, it’s expected that the number of those affected by dementia will continue to rise dramatically in the next 35 years.

According to the Alzheimer's Society, the number of people in the UK affected currently is around 850,000. They estimate that this number will rise to more than 1 million by 2025, and to 2 million by 2051.

Globally, they report that there an estimated 46.8 million people living with dementia currently, and that this figure will rise to 115.4 million by 2050.

The Alzheimer’s Society stresses the importance of increasing funding and research into the condition. They estimate that delaying the development of dementia by five years would help to cut the number of deaths caused by the condition in half.

Currently, research is focusing on the changes that take place in the brain which experts think are behind the progression of dementia; and developing treatments to stop these or slow them down.

Among them are beta amyloid aggression inhibitors, which could help to prevent the formation of plaques in the brain; and drugs which target brain inflammation (which can be a contributing factor in the condition).

How common will visual impairment be in 2050?

Two million Brits live with some form of sight loss, according to NHS Choices. Just under one fifth of these (360,000) are registered blind or partially sighted.

Once more, the rising ageing population is likely to cause this figure to exponentially increase by 2050; but it is thought that the rise in certain underlying factors in sight loss, such as obesity and diabetes, will also contribute towards this.

According to the Royal National Institute of Blind People, by 2050 the number of people in the UK living with sight loss is set to double to four million.

It is thought that age-related macular degeneration (AMD) will account for the largest portion of this increase (rising from 313,000 in 2010 to 887,000 by 2050).

The percentage of sight loss cases caused by glaucoma and diabetic retinopathy are set to drop, but the actual number of cases will rise in absolute terms: from 98,000 in 2010 to 200,000 in 2050 for glaucoma; and from 64,000 in 2010 to 93,000 in 2050 for diabetic retinopathy.

One recent projection from the US was somewhat consistent with these UK figures. Researchers at the Roski Eye Institute in California estimated that the number of people in the US living with visual impairment or blindness would double between 2015 and 2050.

They projected that the number of people who were legally blind would rise from one million to two million; and that the number of Americans with VI would rise from 3.2 million to 6.95 million. Again, the ageing population was cited as the major contributing factor.

As for the rest of the world? The World Health Organisation estimated in 2014 that 285 million worldwide were living with visual impairment. Of these, 39 million were blind.

If we applied UK and US projections to these global figures, in theory, visual impairment would be set to double to around 570 million, and the number of blind people to around 78 million.

Promoting the prevention of ocular injuries, increasing awareness of the importance of regular eye testing, and increasing access to treatment for those with low vision are among the strategies discussed by Access Economics and the RNIB in their 2009 report entitled Future Sight Loss, to try and tackle this expected rise.

Research on new types of treatment for visual impairment is being undertaken; for example stem cell tissue regeneration is one such route currently being explored. Retinal prosthesis is another avenue which may one day prove to life-changing for patients who have already lost their sight.

We’ll be back next week with our final post in this series discussing future health trends.