Against the background of population aging the central question of this thesis is the future development of people with dementia in Germany. Prevalences, incidence rates, co-morbidity and risk factors of dementia are calculated as basis for projection scenarios. Several assumptions of the life expectancy and dementia incidence were combined in multi-state projections. Results of the future number of people with dementia in 2050 range from 2.0 to 3.3 million. Also the costs of dementia, one of the most expensive diseases, were projected.