The number of people with dementia is expected to almost double to 65.7 million by 2030 as the world population ages, according to a World Health Organisation report published yesterday.

And by 2050 the number of sufferers could be more than three times the current figure of 35.6 million, the UN body said.

The report released by WHO and Alzheimer’s Disease International estimates the current cost of treating and caring for those with the condition at €461 billion a year.

Dementia is caused by a variety of brain illnesses that affect memory, thinking, behaviour and the ability to perform everyday activities.

Alzheimer’s disease is the most common cause of dementia and accounts for about 70 per cent of cases.

More than half of sufferers (58 per cent) live in low and middle income countries but this could rise to 70 per cent by 2050.

The report said far more effective diagnosis was needed, as even in high income countries only 20 to 50 per cent of dementia cases are routinely recognised.

“Since we know the prevalence of the disease will explode in this century as we all live longer – the risk of dementia is one in eight for those over 65 and a shocking one in 2.5 for those over 85 – its impact will become greater as the decades go by,” according to Shekhar Saxena, head of the mental health department at WHO.

“We need to increase our capacity to detect dementia early and to provide the necessary health and social care,” said Oleg Chestnov, assistant director general of Noncommunicable Diseases and Mental Health at WHO.

“Much can be done to decrease the burden of dementia. Health-care workers are often not adequately trained to recognise dement