Mixed Pathologies Common in Mild Cognitive Impairment
Patients with a diagnosis of intact cognition had pathological features resembling those with a final clinical diagnosis of MCI.
HealthDay News — A diagnosis of mild cognitive impairment (MCI) is frequently associated with comorbid neuropathologies, according to a study published in the Annals of Neurology.
Erin L. Abner, PhD, from the University of Kentucky in Lexington, and colleagues used data drawn from a large autopsy series of 1337 individuals followed longitudinally from normal or MCI status to death from 4 US Alzheimer's Disease (AD) Centers.
The researchers found that the final clinical diagnoses varied for the 874 individuals ever diagnosed with MCI: 39.2, 46.8, and 13.9% died with an MCI diagnosis, a dementia diagnosis, and a diagnosis of intact cognition, respectively. Those with a diagnosis of intact cognition had pathological features resembling those with a final clinical diagnosis of MCI. Primary age-related tauopathy and brain arteriolosclerosis pathology were more severe in MCI than cognitively intact controls (P <.05 and .001, respectively). Mixed AD neuropathologic changes (ADNC; one or more comorbid pathology) were more frequent than pure ADNC pathology among the group that remained MCI until death (55 vs 22%); the remaining 22% of cases were suspected non-Alzheimer's pathology. Seventy-four percent of individuals who died with MCI did not have high level ADNC, Lewy body disease, or hippocampal sclerosis pathologies; cerebrovascular pathologies were enriched in this group.
"MCI diagnosis usually was associated with comorbid neuropathologies; less than one-quarter of MCI cases showed 'pure' AD at autopsy," the authors wrote.
Abner EL, Kryscio RJ, Schmitt FA, et al. Outcomes after diagnosis of mild cognitive impairment in a large autopsy series [published online February 22, 2017]. Ann Neurol. doi:10.1002/ana.24903