Diagnostic criteria of dementia.

In the past two decades there has been a tremendous effort among clinicians and searchers to improve the diagnostic criteria of the dementias on the basis of the differential neurological and neuropsychological profiles. This was an obligatory requirement for clinical trials and the development of treatments. Over the years it became rapidly evident that the cohorts of patients in studies had some degree of heterogeneity, making it difficult to interpret the results of some studies, particularly in the vascular dementias and the mild cognitive impairment (MCI) group. For example, many sub-types of the vascular group were included in clinical trials, such as the cortical strokes, the lacunar states and the diffuse white matter disease cases, and some of the patients might have had also mixed pathology. In addition, the standard DSM IV criteria for dementia no longer represent our present knowledge of the clinical profile of some of the dementias such as vascular dementia (VaD) and fronto-temporal dementia where the memory impairment is not necessarily the first requirement. To improve the validity of clinical trials and eventually help developing more appropriate treatments, we revised the present diagnostic criteria and made recommendations for some changes in the context of the 2nd Canadian Conference on the Development of Antidementia Therapies, held in 2004 and reviewed in the light of the recent literature as of early 2006. It is expected that in the near future, these dementia criteria for clinical trials will have to be revised again in order to include specific subtypes of the dementias as well as biomarkers, structural and functional imaging.