The latest findings were presented at the annual scientific sessions of the Heart Rhythm Society, held in Boston last week.
The study looked at five years' worth of clinical data for 37,025 patients. Of that group, 10,161 developed AF and 1,535 developed dementia during the study period.
Rebecca Wood, chief executive of the Alzheimer's Research Trust, said: 'This is the first study to find a connection between a common type of heart disease - AF - and Alzheimer's.
'Although not yet published, the researchers believe patients with AF are more likely to develop Alzheimer's and other dementias,' she added.
'If research helps us to understand the relationship between the two conditions, we will be in a better position to develop desperately needed new treatments.'
Comment below and tell us what you think