One in six older adults around the world has experienced some type of abuse, according to recent research by the World Health Organization study. The number is higher than previously thought.

Sixteen percent of people aged 60 or more years had been abused, the study found. The U.S. percentage, at 10%, was slightly below the worldwide average.

Of the 16% globally, the most frequent type of abuse was psychological, at 11.6%. This was followed by financial abuse (6.8%), neglect (4.2%), physical abuse (2.6%) and sexual abuse (0.9%).

No significant gender differences were found.

With the growing population of older people, the problem is predicted to worsen. By 2050, there are expected to be 2 million people aged 60 or more years worldwide. If rates of elder abuse stay the same, that would be an increase from 141 million victims to 320 million victims.

“Despite the frequency and the serious health consequences, elder abuse remains one of the least investigated types of violence in national surveys, and one of the least addressed in national plans to prevent violence,” Alana Officer, a senior health adviser in the WHO Department of Aging and Life Course, said in a statement.

For this study, researchers collected data from 52 previous studies. The study included 28 countries from different regions. Results were published in Lancet Global Health.