Chronic Use of Alcohol and/or Benzodiazepines May Account for Evidence of Altered Benzodiazepine Receptor Sensitivity in Panic Disorder

—Stewart et al raise an im- portant point, namely, the reason patients with panic disorders have abnormal benzodiazepine receptor sensitivity. However, their suggestion that previous alcohol or benzodiazepine exposure could result in anxiogenic responses to flumazenil are but two in a range of possible causes. Before considering these, we can offer some more direct support for their contention that alcoholism may be of relevance. Their bibliography of clinical studies in this area could be usefully expanded to include a recent review that directly addresses the alcoholism/panic disorder comorbidity question and postulates several neurochemical mechanisms for this. 1 Moreover, the marked similarity between the symptoms of withdrawal and panic attacks has been documented. 2 A possible explanation for this is provided by recent neurochemical studies that demonstrated that acute and long-term ethanol exposure increases the sensitivity of the benzodiazepine receptor to the inverse agonist dimethoxy-methyl-β carboline-3-carboxylate (DMCM). 3,4 Since ethanol exposure