Atrial fibrillation (AF), which is a very common disease among the elderly, is already well known as a risk factor for arterial thromboembolism and stroke. The attention of medical research is now focused on establishing a possible role of AF in the development of cognitive impairment in order to include this arrhythmia among risk factors for dementia. The aim of this work was to investigate the relationship between AF and various types of dementia, such as vascular dementia (VaD), Alzheimer's disease (AD) and mixed dementia (MD). The study consisted of 71 VaD, AD or MD patients, 31 males and 40 females. The sample has been divided in 2 groups according to the sex, and these two groups have been analyzed separately. In females, a statistically significant association was found between mini mental state examination (MMSE) and clinical dementia rating (CDR) scores and AF occurrence (r=-0.32; p<0.05; r=0.33; p<0.05). On the contrary, no significant linear correlation was found between AF and a lower activities if daily living (ADL) and instrumental activities if daily living (IADL) scores. In males, AF/MMSE, AF/CDR, AF/ADL and AF/IADL variables have not been found to be linearly related to each other. Unexpectedly, AF turned to be associated to AD more often than to VAD, becoming a possible risk factor for this neurodegenerative disease. Our results are supported by many studies in literature attributing a basic role of brain hypoperfusion in sporadic AD patho-genesis. More and more scientific data suggest that the already well known risk factors for AD could be considered just the top of an iceberg, providing powerful arguments for impaired cerebral perfusion as the primary trigger in the development of this disease. Moreover, the mildly favorable treatment response in patients with AD to therapy that improves cerebral blood flow is a consistent finding; the same cannot be said of antiamyloid treatments. This opens new possibilities to find an effective way to treat this dramatic pathology.