In the first long-term analysis of its kind, researchers report that depressive symptoms that progressively increase in older age might better predict the development of dementia than any other type of depression – and may, in fact, represent an early disease stage. Many studies have linked depressive symptoms with dementia, but failed to take into account that distinct depression courses might represent different underlying mechanisms, with divergent involvement in dementia development. Researchers at the Erasmus Medical Center in the Netherlands analyzed data from a large population-based study of adults older than 55 years. The study has been ongoing since 1990, and the team identified 3,325 individuals who had symptoms of depression but no signs of dementia. Following these individuals for 11 years allowed the research team to draw a number of depression trajectories: maintaining mild symptoms; moderately severe but transient symptoms followed by full remission; mild symptoms that increased, then remitted; mild symptoms steadily increasing; and chronically severe symptoms. Among the 3,325 participants, 434 developed dementia, of which a majority -- 348 -- were diagnosed with Alzheimer's disease. Instead of comparing risk of dementia to the general population, the research team calculated the risk of dementia among those with continuously mild depressive symptoms, and then compared the other disease trajectories to that. Findings published in the journal Lancet Psychiatry show that the patients with mild symptoms had a risk of 10 percent. Among other disease trajectories, only patients with steadily increasing depressive symptoms had a higher risk of developing dementia – 22 percent. The risk was particularly high during the first three years.