A new study, which was published in the journal JAMA Neurology, found that one in 10 Americans over the age of 65 have dementia, while 22% experienced mild cognitive impairment.  It studied nearly 3,500 people via interviews and neuropsychological tests on a randomly selected sample of seniors between June of 2016 and October of 2017. 15% of those who identified as black tested positive for dementia, while 22% had mild cognitive decline. 10% of those who identified as Hispanic had dementia, while 28% had mild cognitive impairment. This compares to 9% of white people who had dementia and 21% had mild cognitive impairment.