Is there A Link Between Dementia and Depression?

April 10, 2015

If you have a relative with dementia you might know first-hand how common it is for them to experience some form of depression, along with forgetfulness and other dementia symptoms. But new research seems to suggest a different link between the two; could depression itself actually be a risk factor for developing dementia later in life? While the jury’s still out, answers are pointing to yes.

Roughly 1 in 10 Americans suffer from some form of depression, most commonly between the ages of 45-64. In recent study that’s getting a lot of attention, 1,700 patients over 50 were followed over 8 years; at the study’s conclusion, the 18% who developed dementia had a significantly higher instance of depression symptoms years before their dementia diagnosis.

Another study went further, following nearly 50,000 subjects over 50, and found that depressed older adults were more than twice as likely to develop vascular dementia. An astounding 65% were more likely to develop Alzheimer’s disease.

So, what’s the connection? Here are the possible causal factors that researchers are pointing to right now:

  • Depression and cortisol: Cortisol is a stress-related hormone that clinically depressed people produce at significantly higher levels. This hormone can have an adverse effect on the hippocampus, which is the area of the brain responsible for new learning and memory retention.
  • Depression and brain deterioration: Depression is believed to contribute to chronic inflammation, which in the brain can lead to damaged blood vessels and restricted blood flow – possibly resulting in the breakdown of neural pathways. “If chronic inflammatory changes are a common feature of depression, that could predispose depressed patients to neurodegenerative changes in later life,” says a 2007 article in Neurochemical Research.

Scientists are also exploring whether depression and dementia might be genetically linked, and are studying depression as a possibly accelerating dementia, since it can be such a drain on cognitive functioning.

For now, neurologists are urging patients suffering from depression – especially those over 50 – to take this research seriously and seek early and aggressive treatment for their symptoms.  One California psychiatrist posted recently that a 10% reduction in midlife depression cases could prevent 68,000 dementia diagnoses. Worth taking seriously, indeed.