Of the 522 people with irregular heartbeat, 23% or 121 people developed dementia
The early signs may persist for many years before the patient visits the right doctor for consultation
Alzheimer's disease is the most common cause of dementia among older adults
For the analysis, van der Steen and colleagues pooled data from 21 smaller randomised trials involving a total of 1097 patients
The researchers recruited 35 people (aged between 45 and 75 years) for the study
For the study, researchers examined data from 2008-2013 on more than 31 million French hospital patients, including more than 1 million who were diagnosed with dementia
The widowed have a 20 per cent increased risk of developing dementia compared to married individuals
It looked at data from Swedish registries for patients between 2006 and 2014
The increased risk was not seen in people who had always slept more than nine hours