Indiana U. Researcher, Hospital, Study Potential Rehab Following 'Mini Stroke' Systolic blood pressure was reduced by 8.71 millimeters of Mercury (mm Hg ) and diastolic blood pressure reduced by 7.18 mm Hg. Other research has found that a change in systolic blood pressure of 5 mm Hg leads to a 14% decrease in stroke risk while a 5 mm Hg reduction in diastolic blood pressure leads to a 42% reduction in stroke risk. 3/12/2010