have been found to interfere with typical hippocampal functioning. Studies of the involvement of the hippocampus in both sole PTSD and SUD diagnosis as well as comorbid PTSD and SUD evidence that the manifestation of these diagnosis are related to decreased hippocampal volume. Hypothalamic pituitary adrenal axis and corticotropin-releasing hormone. The hypothalamic pituitary adrenal (HPA) axis is responsible for the activation of the hormonal stress response system within the human body. Corticotropin-releasing hormone (CRH) is activated by the HPA axis during times of stress. Heightened CRH levels have been shown during symptoms of PTSD (particularly for hyperarousal), drug seeking behavior, substance withdrawal, and drug relapse in humans. Research has conveyed that increased levels of CRH are also related to experiences of euphoria. As CRH levels are elevated in PTSD, this can personify feelings of euphoria experienced when an individual uses substances and increase addiction severity as a result of positive reinforcement from euphoric sensation. This can also affect the interplay between withdrawal symptoms and the increased experience of hyperarousal. As increased levels of CRH have been linked to both withdrawal and hyperarousal, those affected by both diagnoses of PTSD and SUD may subsequently continue to seek substances as a means to avoid these escalated aversive sensations. The described relationship has been used to evidence the self-medication hypothesis. Treatment options Assessment of effectiveness of treatment for comorbid PTSD and SUD has fluctuated. While some treatments for cooccurring PTSD and SUD have shown promising in symptom reduction for both diagnoses, many have not evidenced the ability to be more effective than treatment of PTSD or SUD alone. This is further complicated by high rates of treatment dropout and substance relapse in studies of treatment in this population. Research has focused on two major forms of treatment for those with comorbid SUD and PTSD: treatments that focus on the traumatic experience(s), and treatments that do focus on traumatic experience(s). Research has not definitely concluded that any form of treatment adequately addresses the treatment needs of those who have both PTSD and SUD. Non-trauma focused treatments Treatments that are non-trauma focused do not emphasize the individual's exposure to the trauma memory as a means to treat both PTSD and SUD. Seeking safety is the most well-known non-trauma focused treatment for SUD and PTSD and is based on cognitive behavior therapy. The goal of seeking safety's is to increase the safety of the individual's coping