- Dementia is spreading at a quick pace: Around 225,000 people are estimated to develop dementia this year in the UK. This means one person in every three seconds. In the USA,4 million people are suffering from dementia, out of which 5.2 million are over 65 years of age.Today, approximately 35.6 million people are suffering from dementia globally. This number will double every 20 years and reach 115.4 million by 2050.