Evolution and future directions for the concept of mild cognitive impairment.

The term mild cognitive impairment has been associated with a varying degree of clinical utility and controversy. The concept has been introduced to try and define a pre-dementia period associated with underlying neurodegenerative pathology and a higher likelihood of the person developing a dementia syndrome. As scientific understanding improves then the definition of MCI rightly adapts, meaning that the MCI concept is prone quite rightly to frequent evolution. We consider that we are a long way away from the concept having evolved to a point where it can be embedded with confidence in clinical practice as a diagnosis but should remain as a term primarily for use in research.