A person is diagnosed with dementia every three seconds. And according to a new report, nearly 60% of people who are conditioned are living in poorer countries.
People living in war zones or enduring humanitarian crises are often forgotten victims of a disease that makes them confused and sometimes unable to dress or feed themselves.
Alzheimer's and Alzheimer's Society are talking to people with dementia in Puerto Rico, where communities have been destroyed by hurricane.
Our health and social care correspondent Victoria MacDonald reports.