Study author Robert S. Wilson, a neuropsychologist at Rush University Medical Center in Chicago, and colleagues said the study involved 1,870 people age 65 and older who lived in Chicago and were interviewed every three years for up to 12 years to test their memory and thinking skills. Of those, 1,335 people, or 71 percent, were hospitalized at least once during the study.
Study participants were residents of a geographically defined area that included approximately equal numbers of blacks and whites. The correlation of hospitalization with increased cognitive decline was similar in black and white persons.
Wilson found overall cognitive function declined more than twice as fast after a first hospital stay, compared either to the previous rate before the hospital stay or to people who were not admitted to the hospital.
The study published in the journal Neurology also found on specific cognitive tests, the rate of decline after the first hospital stay was more than three times faster on a long-term memory test and 1.5 times faster on a complex attention test.
"Further research may help to develop strategies to prevent medical problems in older people that lead to hospital stays," Wilson said in a statement. "It could also lead to changes in hospital inpatient and discharge policies."