At 2 of the time points APOE ε4 status was associated with having MCI, a finding which has been consistently found in previous MCI research and is also strongly linked to the risk of progression to dementia.30 The only other characteristic associated with MCI change was having a history of stroke, again somewhat unsurprising given the extensive evidence that stroke patients have higher risk for developing of MCI and dementia.31 The lack of significant association between these factors and MCI status at wave 4 is unexpected and not readily explained. The gene discussed is APOE; the disease is dementia.