stroke hospitalizationLeakier guts may be why older people are more likely to die or have a poor recovery after clot-caused strokes, according to a study in mice presented at the American Stroke Association’s International Stroke Conference 2015.

Researchers found that molecules and bacteria cross the intestinal walls in both aged mice (18-20 months) and young ones (8-12 weeks) after stroke, but only the young were able to clear bacterial infection and resolve inflammation.

After an experimentally induced stroke, with the middle cerebral artery blocked for 90 minutes and then reopened, aged mice had 200 times more bacteria in their abdominal lymph nodes than younger mice, and more frequently tested positive for infection in other extraintestinal organs.

Interleukin-6, a substance produced by the immune system in response to injury or infection and a marker of sepsis (a life-threatening inflammatory response to infection), increased in all mice after stroke but remained elevated in the aged mice that were 50 percent more likely to die within seven days. This suggests that the high mortality in aged mice after stroke is related to exacerbation of intestinal permeability, bacteria getting out of the gut and subsequent induction of sepsis.

Therapies targeting the gut to reduce intestinal permeability may lower the severity of inflammation and improve the prognosis of aged stroke patients, researchers said.