Affected by high blood pressure, elderly people might have difficulty to think clearly, a new study showed.

More evidence has been found that increased blood pressure in older adults is directly related to decreased cognitive functioning, particularly among seniors with already high blood pressure, said the study published in the December issue of the Journal of Gerontology: Psychological Sciences.

The study added another reason for people to watch their blood pressure, researchers at the North Carolina State University said in the study.

The researchers examined blood pressure and cognitive functioning test data collected from a cohort of adults aged 60-87 twice daily for 60 days.

The findings showed that study subjects whose average systolic blood pressure was 130 or higher saw a significant decrease in cognitive function when their blood pressure spiked.

However, study subjects whose average blood pressure was low or normal saw no change in their cognitive functioning, even when their blood pressure shot up, said Dr. Jason Allaire, an assistant professor of psychology at the university who co-authored the study.

Specifically, the study showed a link between blood pressure spikes in seniors with high blood pressure and a decrease in their inductive reasoning, said Allaire.

"Inductive reasoning is important, because it is essentially the ability to work flexibly with unfamiliar information and find solutions," he said.

The findings may indicate that mental stress is partially responsible for the increase in blood pressure, and the corresponding breakdown in cognitive functioning, he said.

However, normal fluctuations in blood pressure likely play a role as well, Allaire said in the study.