Studies have shown people with PTSD demonstrate reduced levels of NPY, possibly indicating their increased anxiety levels.Other studies indicate that people with PTSD have chronically low levels of serotonin, which contributes to the commonly associated behavioral symptoms such as anxiety, ruminations, irritability, aggression, suicidality, and impulsivity. Serotonin also contributes to the stabilization of glucocorticoid production. Dopamine levels in a person with PTSD can contribute to symptoms: low levels can contribute to anhedonia, apathy, impaired attention, and motor deficits; high levels can contribute to psychosis, agitation, and restlessness.Several studies described elevated concentrations of the thyroid hormone triiodothyronine in PTSD. This kind of type 2 allostatic adaptation may contribute to increased sensitivity to catecholamines and other stress mediators. Hyperresponsiveness in the norepinephrine system can also be caused by continued exposure to high stress. Overactivation of norepinephrine receptors in the prefrontal cortex can be connected to the flashbacks and nightmares frequently experienced by those with PTSD. A decrease in other norepinephrine functions (awareness of the current environment) prevents the memory mechanisms in the brain from processing the experience, and emotions the person is experiencing during a flashback are not associated with the current environment.There is considerable controversy within the medical community regarding the neurobiology of PTSD. A 2012 review showed no clear relationship between cortisol levels and PTSD. The majority of reports indicate people with PTSD have elevated levels of corticotropin-releasing hormone, lower basal cortisol levels, and enhanced negative feedback suppression of the HPA axis by dexamethasone.
Tricyclic antidepressants are equally effective but are less well tolerated. Evidence provides support for a small or modest improvement with sertraline, fluoxetine, paroxetine, and venlafaxine. Thus, these four medications are considered to be first-line medications for PTSD. Benzodiazepines
Benzodiazepines are not recommended for the treatment of PTSD due to a lack of evidence of benefit and risk of worsening PTSD symptoms. Some authors believe that the use of benzodiazepines is contraindicated for acute stress, as this group of drugs can cause dissociation. Nevertheless, some use benzodiazepines with caution for short-term anxiety and insomnia. While benzodiazepines can alleviate acute anxiety, there is no consistent evidence that they can stop the development of PTSD and may actually increase the risk of developing PTSD 2–5 times. Additionally, benzodiazepines may reduce the effectiveness of psychotherapeutic interventions, and there is some evidence that benzodiazepines may actually contribute to the development and chronification of PTSD. For those who already have PTSD, benzodiazepines may worsen and prolong the course of illness, by worsening psychotherapy outcomes, and causing or exacerbating aggression, depression (including suicidality), and substance use. Drawbacks include the risk of developing a benzodiazepine dependence, tolerance (i.e., short-term benefits wearing off with time), and withdrawal syndrome; additionally, individuals with PTSD (even those without a history of alcohol or drug misuse) are at an increased risk of abusing benzodiazepines.