Mild cognitive impairments predict dementia in nondemented elderly patients with memory loss

Background: Some elderly individuals exhibit significant memory deficits bu t do not have dementia because their general intellect is preserved and the y have no impairments in everyday activities. These symptoms are often a pr ecursor to Alzheimer disease (AD), but sometimes dementia does not occur, e ven after many years of observation. There is currently no reliable way to distinguish between these 2 possible outcomes in an individual patient. We hypothesized that clear impairments in at least 1 cognitive domain in addit ion to memory would help identify those who will progress to AD. Objective: To determine whether nondemented patients with impairments in me mory and other domains are more likely than those with memory impairment al one to develop AD. Design and Methods: In a retrospective study, we evaluated 48 nondemented, nondepressed patients with clinical and psychometric evidence of memory imp airment who were followed up for 2 or more years. Age-adjusted normative cr iteria were used to identify whether additional impairments were present in language, attention, motor visuospatial function, and verbal fluency at th is initial evaluation. The presence or absence of dementia after 2 years an d at the most recent neurological evaluation was compared in subjects with normal scores in all 4 of these cognitive areas apart from memory (M-) and those with impairment in 1 or more of these areas (M+). Outcomes were adjus ted for age, intelligence at initial evaluation, and years of education. Results: Of the 48 nondemented patients with memory loss, 17 met M- criteri a, leaving 31 in the M+ group. Deficits in block design were the most frequ ent abnormality other than memory loss. At the 2-year follow-up, 1 M-subjec t (6%) had progressed to AD, whereas 15 (48%) of the M+ group had progresse d to AD (P=.003). At the most recent follow-up (mean +/- SD, 4.0 +/- 2.0 ye ars), 4 (24%) of the M- patients progressed to AD compared with 24 (77%) of the M+ patients (P<.001). Conclusions: Among nondemented elderly patients, memory loss alone rarely p rogresses to dementia in the subsequent 2 years. However, the risk of demen tia is significantly increased among patients with clear cognitive impairme nts beyond memory loss. Further study is needed to determine whether patien ts with impairments limited to memory loss have a distinctive clinical cour se or pathophysiology.