Mild cognitive impairment--the continuing challenge of its "real-world" detection and diagnosis

Although mild cognitive impairment (MCI) is a controversial entity with variable application in clinical and epidemiological research, it remains an important construct in terms of targeting interventions to prevent dementia. However, very little is known about how MCI may be recognized during clinical attention in routine practice. This work was undertaken to summarize recent findings relevant to the presentation and initial detection of MCI. A narrative review is presented of literature relevant to the presentation and detection of MCI in primary care. Population screening for impaired cognitive function and/or informant-reported decline/impairment is unlikely to be feasible or acceptable. MCI detection will therefore rely largely on subjective memory complaint (SMC) as a presenting symptom, accepting the fact that, although possibly a valid self-appraisal of underlying function in older persons, SMC is heterogeneous in its etiology and poorly predicts medium-term dementia risk. SMC is common in older populations when asked about and is often concerning to the person acknowledging it. However, it is rarely reported to general practitioners. Help-seeking of this nature is influenced partly by the perceived severity of the symptom but also by contextual factors such as concerns about a family history of dementia, although very little research has investigated this. If an intervention were proven to be effective for preventing transition from MCI to dementia in the near future, there would be a serious lack of knowledge about how MCI can be identified in routine clinical practice.