Prazosin for PTSD. Does it help?
According to the statistics, post-traumatic stress disorder (PTSD) affects about 10 percent of women and 2 percent of men worldwide. The characteristic symptoms of PTSD are: intense fear, feeling of helplessness, intrusive memories about the traumatic event, when the injury was received, as well as numbness on the background of the nervous system activity, which, on the contrary, increases extremely. Moreover, PTSD has a direct influence on the hypothalamic-pituitary-adrenal axis function and also causes sleep disturbances and different types of severe depression. In the military personnel, and especially in those, who are involved in military operations, the risk of PTSD development is much higher.
Scientists have found that in some cases elevated norepinephrine levels, which rise during a stressful situation, may persist for a long time after – this is the initial point where PTSD begins. Elevated norepinephrine levels in the human body activate the amygdala (a section of the brain responsible for a sense of fear) and reduce the effect of the processes, occurring in the prefrontal cortex, – process, which helps us to overcome a sense of fear. Also excess norepinephrine, stimulating alpha-1 and beta receptors in amygdala, strengthen the feeling of fear and trigger strong emotional experiences from the past. In fact, alpha-1 suspends the prefrontal cortex function (the main function of the prefrontal cortex is to overcome negative thoughts and memories and decrease the amygdala activity, letting us know that we are safe and there is nothing to be afraid of). According to the radiographic findings, people, who suffered from PTSD, had the observed weakening of the prefrontal cortical functions, and vice verse, increased amygdala activity.
This observation in particular has become a major step towards the development of drugs for the PTSD treatment. Previously Prazosin had only been used for the high blood pressure, but now it is also used (and quite successfully) to eliminate the symptoms of PTSD.
Prazosin blocks α1-adrenergic receptors in smooth muscle cells of the blood vessels and eliminate the vasoconstrictor effect of norepinephrine and circulating epinephrine neurotransmitters. This results in the expansion of the arterial and venous vessels, decrease in the total peripheral resistance and the venous return, and low arterial and venous pressure. Since these drugs do not block the presynaptic α2-adrenergic receptors, they do not increase the norepinephrine production from adrenergic nerve fibers (which does not induce the β1-adrenergic receptors overstimulation and preserves the blocking of α1-adrenergic receptors in blood vessels).
Prazosin is mostly prescribed to those patients, who suffer from the chronic PTSD. Recently, in a small study, NIMH researchers have found that adding the daily dose of Prazosin to the PTSD therapy of those patients, who are already taking Prazosin before bedtime, weakens the expression of PTSD symptoms and stress responses to reminders of the trauma. Prazosin is also often prescribed to people suffering from PTSD, anxiety and panic disorders to eliminate nightmares.