Objective cognitive impairment measures provide the best predictor for progression from mild cognitive impairment (MCI) to dementia, according to a study by the Centre for Healthy Brain Ageing (CHeBA) at UNSW Sydney. The findings were published in The American Journal of Geriatric Psychiatry.
Mild Cognitive Disorder is a condition that is conceptualised as a stage between normal cognition and dementia. MCI is diagnosed according to three criteria: subjective cognitive decline, objective cognitive impairment, and no significant functional impairment.
Researchers are especially interested in MCI as it may the opportune time to try new drugs to prevent Alzheimer’s disease, the most common form of dementia.
Lead author and CHeBA Co-Director, Professor Brodaty, said the research aimed to clarify the impact of different applications of MCI diagnostic criteria on dementia incidence predictions. This is important because the wrong definition may mean trials of new drugs may not be choosing those people most likely to progress to Alzheimer’s.
“We found the predictive accuracy of different definitions of MCI was poor,” said Professor Brodaty.
The study evaluated 56 different algorithms of diagnostic criteria for MCI to predict dementia progression over six years in a study of 618 community-dwelling individuals participating in CHeBA’s Sydney Memory & Ageing Study. Co-investigator. Dr Liesbeth Aerts, calculated that according to which diagnostic criteria were applied, baseline MCI prevalence varied between 0.4% and 30.2% and progression to dementia ranged between 15.9% and 61.9%.
Surprisingly, the most accurate prediction was achieved by simply using performance on objective cognitive tests. Accuracy was not improved by including measures of subjective cognitive decline or mild functional impairment.
“The major issue is that there are currently no standard operationalisations for MCI diagnosis, or guidelines around how each of the different components of the definition are strictly defined,” said Professor Brodaty.
“Our findings highlight that clinical assessment procedures need to be refined in order to improve the identification of individuals with MCI and pre-dementia. A combination of biological markers and other risk factors with standard clinical assessment may lead to more accurate prediction of which people with memory complaints are most likely to progress to Alzheimer’s disease.”