2-4 The arbitrary nature of the label can be seen most explicitly in the neuropsychological criteria, which may specify the threshold for applying the terms (one or one and a half standard deviations less than age-matched controls), the composition of the battery, and the norms.5,6 The criteria concerning preserved or relatively preserved

activities of daily living also permit considerable variability as to where the line is drawn by different clinicians. How complex must an impaired instrumental activity of daily living be before the label MCI is applied? For that matter, how simple should the task be before the affected person Inhibitors,research,lifescience,medical is said to convert to click here Alzheimer’s disease (AD)?7,8 Differences in an individual’s performance of life’s tasks create both patient and clinician variability in perceptions as well as cross-cultural challenges in multinational studies (Gaines A, Whitehouse PJ, unpublished data). The existence of a continuum Inhibitors,research,lifescience,medical of cognitive changes is illustrated by MCI being bounded on one side by AD and on the other by labels such as age-associated Inhibitors,research,lifescience,medical memory impairment (AAMI)9 or age-related cognitive decline.10 The emergence of AAMI was also closely linked to attempts to develop medicines to treat this condition. The criteria for applying this label included demonstrating test performance one standard deviation below younger-age controls, thus creating a large number

of older individuals who could be labeled with AAMI. Yet this condition is generally considered to be“normal aging.” Whether MCI is normal or not is at the heart of Inhibitors,research,lifescience,medical the conceptual and practical ambiguities associated with this concept. Clinicians know logically that there is a time in the life course of a patient, who will eventually be diagnosed as having AD, when the symptoms are present, but not sufficiently severe to warrant the label dementia. Any progressive medical condition must have a phase in Inhibitors,research,lifescience,medical which the symptoms are emerging, but not of sufficient intensity to warrant a disease label. In medicine, increasing attention is being paid to so-called preclinical states, such

as in hypertension, depression, and Parkinson’s disease. Thus, it is not at all surprising that different variants of MCI have been identified, including amnestic MCI, MCI with symptoms in several different through cognitive domains, and MCI with focal symptoms in an intellectual area other than memory.8,11 The MCI associated with frontal lobe dementia and vascular dementia would more likely be predicted to be nonamnestic. The symptoms in MCI are mild and perhaps more variable than in dementia; therefore, it is not surprising that the outcomes of longitudinal follow-up studies and drug studies might also be more variable. The logically complete set of outcomes for a patient with MCI includes no change over time, further deterioration or even improvement.