heightened and reduced activity reported 34, 42. Moreover, acute and chronic alcohol use differ in their effects on HPA axis activity, with disturbed activity in AD potentially due in part to the impact of chronic alcohol consumption on brain regions involved in negative feedback 43. HPA disturbance in AD may also be due to the high comorbidity of AD with major depression (MD). Support for an etiologic role for altered stress system activity in the pathophysiology of MD is growing, with some evidence that genetic variation may be involved 44–46. Epidemiological research suggests MD may be the primary pathology in some AD patients 47. Results of AD studies selecting for 48 or screening out 49 a history of MD suggest disturbance of the stress system in some AD patients may be due to the well-documented disturbance of this system in MD.
