Data from 6257 older adults (aged 55-90) evaluated from 2005-2012 has revealed that concerns about memory should be taken seriously, with subjective complaints associated with a doubled risk of developing mild cognitive impairment or dementia, and subjective complaints supported by a loved one being associated with a fourfold risk. Complaints by a loved one alone were also associated with a doubled risk. Among those with MCI, subjective complaints supported by a loved one were associated with a threefold risk of converting to dementia.
Of the 4414 initially cognitively normal, 14% developed MCI or dementia over the course of the study (around 5 years); of the 1843 with MCI, 41% progressed to dementia.
 The source of cognitive complaints predicts diagnostic conversion differentially among nondemented older adults. Alzheimer's & Dementia. 10(3), 319 - 327.(2014).