It

has been estimated that around a third of nursing home patients in the USA take more than two anticholinergic drugs and 5% more than five.35 It is surprising that this important environmental risk factor has not been taken into account in epidemiological studies of environmental risk in MCI. Conclusion MCI rates are likely to increase rapidly in parallel with the extension of life expectancy at higher ages. Current estimates of prevalence are limited by problems related to case identification, but, in the light of several revisions of the original definition, appear to be converging at around Inhibitors,research,lifescience,medical 5% of the general population with around 15% per year going on to develop dementia. Mortality risk is doubled in MCI subjects. While the principal value of MCI remains the identification of persons in the first stages of neurodegenerative disease, it also learn more covers other forms Inhibitors,research,lifescience,medical of cognitive impairment due to multiple causes, making the construction of meaningful hypothetical etiological models extremely difficult. The few studies of risk that have been carried out have largely focused on known risk factors for dementia and there is a clear need for

longitudinal epidemiological studies that examine a wider range of genetic, biological, demographic, and environmental Inhibitors,research,lifescience,medical risk factors. Such studies are extremely costly and difficult Inhibitors,research,lifescience,medical to justify for a health state that is subclinical, poorly defined, often benign, and for which no specific treatment is currently available. Epidemiologists in this area should explore the possibility of grafting this type of

study on to existing longitudinal databases of population aging, which cover a much broader Inhibitors,research,lifescience,medical range of risk factors than those included in studies of dementia.
On the basis of the descriptions presented elsewhere in this issue, it is clear that it is difficult to identify or develop an animal model reproducing most, if not all, the features of human mild cognitive impairment (MCI). To begin with, an animal cannot complain about memory, tuclazepam and it is difficult to assess whether its daily life is affected. However, correspondence between animal models and human pathology is only partial in all neurodegenerative diseases including Alzheimer’s disease (AD) and Parkinson’s disease. Nevertheless, even if they only partially reproduce the disease, animal models are quite useful for at least two purposes: understanding the pathogenic mechanisms of a disease; and testing the activity of new drugs to assess their potential activity prior to clinical trials. General features of MCI animal models If the purpose is to understand pathogenic mechanisms, the animal model should mimic as closely as possible the symptoms, neuropathology, and mechanisms of the disease.