 This is the VOA Special English Health Report. Dementia is the loss of mental abilities caused by brain disorders that affect memory, thinking, behavior, and judgment. The most common cause of dementia, especially in older people, is Alzheimer's disease. It causes up to 70% of dementia cases. Worldwide, an estimated 36 million people are living with dementia. A new report predicts that number will increase to more than 115 million by 2050. The report is from the World Health Organization and Alzheimer's Disease International. The number of cases in the heavily populated developing world is expected to grow as more people live longer. The report says more than half of those with dementia now live in low and middle income countries. This number is likely to rise to more than 70% by 2050. People are living longer because of better healthcare and increasing wealth. But the report says dementia is not a normal part of growing old. Shakar Saxena is the Director of Mental Health and Substance Abuse Research at the WHO. He says dementia is often not recognized. It is commonly mistaken for an age-related decline in functioning, because it can mimic age-related problems. And also, it progresses slowly. Even in high-income countries, only one-fifth to one-half of the cases of dementia are routinely recognized. This percentage is much lower than the number of cases in low-income countries. Martin Prince is a professor at King's College, London. He says many people wrongly believe that dementia and Alzheimer's Disease are not problems in poorer countries. He says findings from recent studies in Western Africa conflict with the belief that Alzheimer's Disease is rare on the continent. There are fewer older people because life expectancy is shorter. But among people who live to old age, he says, rates of dementia look quite similar to high-income countries. The WHO says treating and caring for people with dementia currently costs the world $600 billion a year. That includes the reduction of earnings for people with dementia and their caregivers. The agency calls for greater efforts to identify dementia early and to educate the public and provide better care. Dementia may be incurable, but health officials say much can be done to improve the lives of people who have it and support their families and caregivers. To learn more about Alzheimer's Disease, go to voaspecialenglish.com. For VOA Special English, I'm Carolyn Presuti.