According to some medical reports, capillaries have a unique method of ejecting debris, such as blood clots, cholesterol or calcium plaque, that blocks supply of vital nutrients to brain cells.

A new study at Northwestern University's (NU) Feinberg School of Medicine (FSM) has revealed this fact.

The capillaries spit out the blockage by growing a membrane that envelopes the obstruction and then pushes it out of the blood vessel.

It was also found by the scientists that this critical process is 30 to 50 percent slower in an aging brain and likely results in the death of more capillaries.

Jaime Grutzendler, study co-author and principal investigator and assistant professor of Neurology and Physiology at FSM, said, "The slowdown may be a factor in age-related cognitive decline and may also explain why elderly patients who get strokes do not recover as well as younger patients."

It was also noted by the report that scientists have long understood how large blood vessels clear blockages: blood pressure pushes against the clot and may eventually break it down and flush it away, or clot busting enzymes rush to the scene to dissolve a blockage.

However, very little was previously known about how capillaries clear blockages. It was demonstrated by the study for the first time that enzymes and blood pressure aren't efficient at clearing capillary clots.

Those mechanisms only work half the time and only when blood clots are involved, not other types of debris, particularly cholesterol, which is difficult to dissolve.

Grutzendler and colleagues asked, "So what happens to the blood vessels that that aren't cleared out? Do they die, or does some other mechanism take over?"

They, to find out, created micro-clots, tagged them with a red fluorescent substance and infused them into the carotid arteries of mice. (With Inputs from Agencies)