There is a growing body of research on the use of Twitter by people with health conditions, but it does not include people with dementia. In this brief report, we aim to: (1) determine whether people with dementia are using Twitter; (2) provide an estimate of the number of Twitter account holders who identify as having a diagnosis of dementia; and (3) examine the demographic characteristics of these account holders. Tweetcatcher was used to identify tweets containing the search terms ‘dementia’ or ‘Alzheimer’. These data were systematically searched to locate account holders who identified themselves as having a diagnosis of dementia, and a content analysis was conducted of these account holders’ profiles. Thirty account holders self-identified as having a diagnosis of dementia. The average age of account holders was 59 years and the majority were located in North America or the UK. Although the majority of account holders reported having Alzheimer’s disease or did not specify a type of dementia, some rare forms of dementia were also evident. The sample consisted of relatively young account holders and contained more men, which might suggest that other groups are under-represented on Twitter. The majority of account holders considered themselves a dementia activist or were affiliated with a dementia organisation. The findings suggest that people with dementia, with varying demographic characteristics and a range of diagnoses, are active on Twitter. These account holders are more frequently male, relatively young, and dementia activists.