Levothyroxine treatment and incident dementia in adults with atrial fibrillation

The study population included all adults with diagnosed AF (n = 156,104) aged ≥ 45 years in Sweden without an earlier recorded diagnosis of dementia. Individuals with a dispensed prescription of levothyroxine on two or more occasions between July 1 2005 and December 31 2006 in Sweden were considered exposed (n = 12,978; 8.3%), and were compared to all other patients with AF without this treatment.