As public awareness of and exposure to Alzheimer's disease and related dementias (ADRD) have increased worldwide, the fear of developing ADRD, or dementia-related anxiety (DRA), is expected to increase as well. It was hypothesized that at least part of what makes dementia so anxiety provoking, is the association of ADRD with older adults, an often stigmatized group. To test this hypothesis, two online studies examined how ageist beliefs contribute to DRA; the roles of ADRD-related factors, such as self-perceived risk and personal exposure, were also examined. Study 1 included university students (n = 295, age range: 18 to 58 years, M age = 21.16, SD age = 4.85) to determine what factors may contribute to young adults' DRA. Study 2 included adults of all ages (n = 352, age range: 18 to 81 years, M age = 37.85, SD age = 12.88) to determine whether Study 1 results were replicable among adults of all ages. Hierarchical multiple regressions were used. Results from both studies demonstrated that being female and having higher self-perceived ADRD risk and benevolent ageism uniquely explicated higher levels of DRA. Within Study 2, significant effects of both benevolent and hostile ageism were observed, suggesting that diverse negative attitudes toward older adults are associated with DRA. It is possible that strong ageist attitudes stigmatize older adults as those who are forgetful and this may contribute to DRA, as age is a major risk factor for developing dementia. Study limitations and directions for future research are discussed.