SAN ANTONIO (AP) -- Central Texas researchers are directing a $37 million, five-year nationwide study to evaluate benefits of two anti-clotting agents and two levels of blood pressure management.

They are recruiting stroke victims like Renato Ornelas for the new study.

Doctors are testing whether a new drug regimen, combined with strict blood pressure control, can cut substantially the recurrence of small but debilitating strokes.

Ornelas, who suffered a subcortical stroke four months ago, is at high risk of having another such attack.

Aspirin and clopidogrel, sold under the brand name Plavix or Iscover, are anticoagulants that keep blood from clotting. A study published two years ago concluded the combination of the two offers major benefits to people who suffer chest pains because of cardiovascular disease.

Possible benefits to stroke patients were suggested in that study, but the idea still needs to be tested, said Dr. Oscar Benavente, associate professor of neurology at the health science center.

"(Heart patients) are not the same patients as patients with cerebrovascular disease," said Benavente, who is directing the new stroke study with colleague Dr. Robert Hart, a professor of neurology. "Therefore, there is a need to test the medication in these patients, particularly with strict control of blood pressure."

Anticoagulant medications have been shown in earlier studies to bring an increased risk of bleeding, making blood pressure control important. Half of the patients in the new study will get aspirin and half will get a combination of the two drugs.

Researchers will divide each of the groups so that half will take medication aimed at keeping systolic blood pressure between 130 and 149, and the rest will receive medication with the aim of keeping their blood pressure below 130 systolic.

The top number in a blood pressure reading, systolic pressure measures the force of blood against the artery wall during a heartbeat.

"We know that lowering blood pressure is extremely important, but we don't know how aggressive we should be in lowering blood pressure," said Benavente. "In this study, we are going to measure whether those two interventions (medication and blood pressure control) are going to reduce stroke recurrence as well as cognitive decline," Benavente said.

Ornelas was one of the first partients to enroll in the study and doctors hope to recruit at least 125 more in the area. In all, they want to recruit 2,500 patients from 14 locations in the United States and Canada.

"The doctors are taking very good care of me," said Ornelas, 81. "I am glad they are experimenting to find out what works better. I hope I can help them."

A clot had lodged within a small blood vessel deep inside the retired letter carrier's brain, cutting off oxygen to some of the fragile neurons that controlled his motor skills. Such subcortical strokes are likely to recur, particularly in people like Ornelas, who have high blood pressure. Brain damage can accumulate and cause dementia, or a loss of cognitive skills.

Copyright 2003 The Associated Press. All rights reserved.