MCI Associated With Comorbid Neuropathologies
Mixed Alzheimer's disease neuropathic changes are more frequent than pure ADNC among those with MCI.
HealthDay News — A diagnosis of mild cognitive impairment 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 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 percent 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 < 0.05 and 0.001, 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 versus 22 percent); the remaining 22 percent 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 write.
Abner EL, Kryscio RJ, Schmitt FA, et al. Outcomes after diagnosis of mild cognitive impairment in a large autopsy series. Ann Neurol. 2017; doi: 10.1002/ana.24903. [Epub ahead of print]