Researchers find clues that depression may speed brain aging
Depression has long been linked to certain cognitive problems, and depression late in life even may be a risk factor for the development of Alzheimer's. Yet how depression might harm cognition isn't clear.
One possibility: Brain cells communicate by firing messages across connections called synapses. Generally, good cognition is linked to more and stronger synapses. With cognitive impairment, those junctions gradually shrink and die off. But until recently, scientists could count synapses only in brain tissue collected after death.
The lower the density, the more severe the depression symptoms, particularly problems with attention and loss of interest in previously pleasurable activities, Yale neuroscientist
"We think depression might be accelerating the normal aging," she said.
Her studies so far are small. To prove if depression really worsens that decline would require tracking synaptic density in larger numbers of people as they get older, to see if and how it fluctuates over time in those with and without depression, cautioned
Esterlis is planning a larger study to do that. It's delicate research. Volunteers are injected with a radioactive substance that binds to a protein in the vesicles, or storage bins, used by synapses. Then during a PET scan, areas with synapses light up, allowing researchers to see how many are in different regions of the brain.
Esterlis said there are no medications that specifically target the underlying synapse damage.
But other brain experts said the preliminary findings are a reminder of how important it is to treat depression promptly, so people don't spend years suffering.
"If your mood isn't enough to make you go and get treated, then hopefully your cognition is," said Dr.
Still, she cautioned that normal cognitive aging is a complicated process that involves other health problems, such as heart disease that slows blood flow in the brain. It might be that depression, rather than worsening synaptic decline, just makes it more obvious, Sano noted.
With depression "at any age, there's a hit on the brain. At an older age the hit may be more visible because there may already be some loss," she explained.
Indeed, another way the brain ages: The blood-brain barrier, which normally protects against infiltration of damaging substances, gradually breaks down,