Background
Alzheimer’s disease is one of the most common causes of dementia. It currently affects 4 million subjects in the European Union. The prevalence of Alzheimer’s disease is expected to increase substantially the next decades due to the aging population. Alzheimer’s disease severely affects the quality of life of patients and their relatives. It also poses a major burden to the health care system.

According to the current diagnostic criteria, Alzheimer’s disease can only be diagnosed when a subject is demented. This means that the subject must have severe impairments in activities of daily living. However, subjects with AD already experience symptoms before they are demented. It would be important to identify subjects with AD before they are demented, as this will allow to start interventions that may improve cognition or prevent the progression of the disease in an earlier stage than is possible now.

Aims of the study
The overall aim of the study was to investigate how subjects with Alzheimer’s disease can be identified before they are demented. The specific aims were:
- The development of diagnostic criteria for predementia Alzheimer’s disease in a clinical setting.
- The development of screening guidelines for predementia Alzheimer’s disease in the general population.

Study outline
Diagnostic criteria for predementia Alzheimer’s disease will be developed based on a group of 880 subjects who attended a memory clinic with cognitive complaints but who were not demented. At the time of the first visit, we tested a number of possible diagnostic markers for Alzheimer’s disease. Next, we reassessed these subjects 2 to 3 years later in order to identify subjects who progressed to Alzheimer-type dementia at follow-up. Then we investigated which diagnostic markers collected at the time of the first visit could best identify subjects with Alzheimer-type dementia at follow-up. These markers will be used for the development of clinical criteria for predementia Alzheimer’s disease.

Screening guidelines for predementia Alzheimer’s disease will be developed based on subjects who participated in a number of ongoing population-based studies in Europe. We selected 13.000 subjects who were not demented at the time of the first visit and investigated a number of possible markers and risk factors for Alzheimer’s disease. Next, we reassessed subjects up to 12 years later in order to identify subjects who progressed to Alzheimer-type dementia at follow-up. Then we investigated which markers and risk factors collected at the time of the first visit could best predict subjects with Alzheimer-type dementia at follow-up. These markers and risk factors will be used for the development of screening guidelines for predementia Alzheimer’s disease.

Study results
The data analysis is still ongoing.