Improving the diagnosis and prediction of progression in mild cognitive impairment

Mild cognitive impairment (MCI) is a clinical condition conceptualized as a stage between normal cognition and dementia. To diagnose it requires subjective cognitive impairment, evidence of cognitive impairment on cognitive testing but no abnormality in a person's functioning and no evidence of dementia (American Psychiatric Association, 2013). There has been growing interest in the condition over the past two decades or so because people with MCI are much more likely than people with no cognitive impairment to progress to dementia (Roberts et al., 2013). However, a significant percentage of people with MCI will not progress to dementia and some will revert to having normal cognition. Rates of progression and reversion to normal cognition vary widely in different studies (Manly et al., 2008). People with MCI experience worry about their symptoms and this is partly alleviated by receiving a diagnosis of MCI and being reassured they do not have dementia (Gomersall et al., 2017). The benefits of diagnosis also include gaining a greater understanding of their symptoms and accessing clinical support but a significant amount of uncertainty remains with regards to the risk of progression and recipients of the diagnosis remain frustrated at the lack of treatments for MCI (Gomersall et al., 2017). There has been much interest in improving the prediction of progression to dementia from MCI but to date, the best predictors of progression remain structured clinical and functional assessments, with some additional benefit from measures of cortical volume/thickness from brain imaging (Korolev et al., 2016). As yet, however, there are no interventions that can prevent (Kane et al., 2017) or treat (Cooper et al., 2013) MCI so it seems set to remain an important clinical entity for the foreseeable future.