the present invention provides a method for determining the cerebral hemodynamic model for depression , using carotid duplex ultrasound to establish percent stenosis of a right external carotid artery and a left external carotid artery , and transcranial doppler ultrasound instrument to measure mean flow velocity within the cerebral arteries including the right and left internal carotid arteries , right and left middle cerebral arteries , right and left anterior cerebral arteries , right and left posterior cerebral arteries , and basilar artery . percent carotid stenosis and mean flow velocity values in cerebral arteries are used to determine the cerebral hemodynamic model associated with depression in men and women , respectively .