According to a latest research, depression symptoms that progressively increase over time in older age could predict higher dementia risk. The study included 3325 adults aged 55 and over, who all had symptoms of depression but no symptoms of dementia at the start of the study.

The data was gathered from the Rotterdam Study, a population-based cohort study of various diseases in the Netherlands, which allowed the authors to track depressive symptoms over 11 years and the risk of dementia for a subsequent 10 years.

Using the Center for Epidemiology Depression Scale (CES-D) and the Hospital Anxiety and Depression Scale-Depression (HADS-D), the authors identified five different trajectories of depressive symptoms - low depression symptoms; initially high symptoms that decreased; low starting scores that increased then remitted; initially low symptoms that increased; and constantly high symptoms.

They say that at the molecular levels, the biological mechanisms of depression and neurodegenerative diseases overlap considerably including the loss of ability to create new neurons, increased cell death and immune system dysregulation.

According to Dr M Arfan Ikram from Erasmus University Medical Center, "More research is needed to examine this association, and to investigate the potential to use ongoing assessments of depressive symptoms to identify older adults at increased risk of dementia."