Dementia has unseated AIDS as one of the world’s top killers, new figures from the World Health Organization show, as drugmakers struggle to either curb or cure it.

Alzheimer’s disease and other forms of dementia killed 1.54 million people in 2015, more than twice the number of deaths reported rom the disease in 2000, according to documents posted on the WHO website last month. It replaced HIV/AIDS as No. 7 on the global health watchdog’s list of the 10 biggest causes of death worldwide. New therapies helped push fatalities from HIV/AIDS from 1.5 million down to 1.1 million over the same 15-year period.

Drugmakers have struggled to understand Alzheimer’s, with Merck & Co. abandoning a study this week, less than three months after a similar defeat for Eli Lilly & Co. About 100 experimental treatments have failed to slow the condition, which dismantles memories and leaves patients unable to take care of themselves. Dementia afflicts 47 million people worldwide and the number of cases will probably rise to 75 million by 2030, said Shekhar Saxena, director of the WHO’s department of mental health and substance abuse.

Dementia’s climb up the ranking is partly due to the aging of society, and partly to doctors diagnosing it more frequently, he said.

Bloomberg News