Conversely, PTSD is linked to low cortisol levels, which appears to be a heritable trait (Yehuda, 2009; Radley et al., 2011). In this case, enhanced glucocorticoid feedback may impair cortisol responses that are essential for normal processing of stressful information: in effect, patients are on the “left arm” of the inverted U-shaped curve relating hormone action and performance. A role for low “trait” cortisol in PTSD is supported by recent studies showing efficacy of exogenous corticosteroids in reducing symptoms in the clinic (Suris et al., 2010).
