Psychiatry Research, 17, 295-308 Elsevier 295 Lactate Infusions and Panic Attacks: Do Patients and Controls Respond Differently? Anke Ehlers, Jiirgen Margraf, Walton T. Roth, C. Barr Taylor, Richard J. Maddock, Javaid Sheikh, Maya L. Kopell, Kristin L. McClenahan, Denis Gossard, Geoffrey H. Blowers, W. Stewart Agras, and Bert S. Kopell Received August 2. 1985; revised version received November 18. 1985; accepted December 5, 1985. Abstract. Ten patients with panic disorder or agoraphobia with panic attacks and 10 normal controls received infusions of normal saline (placebo) and sodium lactate in a single-blind design. The time course of changes in the dependent variables was closely monitored, and expectancy biases and demand characteristics were minimized. Lactate increased self-reported anxiety and heart rate equally in patients and controls. The only variables showing statistically different responses between the groups were systolic and diastolic blood pressure. Overall, in both groups, the effects of lactate were quite similar to states of natural panic or anxiety for both self-report measures and heart rate. Patients had a tendency to endorse somatic symptoms indiscriminately. Our data do not support response to lactate as a biological marker of proneness to panic attacks. Key Words. Panic disorder, agoraphobia, anxiety, sodium lactate infusion, heart rate, blood pressure. Agoraphobia with panic attacks and panic disorder are characterized by frequent panic attacks, i.e., discrete periods of apprehension or fear accompanied by such symptoms as dyspnea, palpitations, chest pain, and fear of dying (DSM-III, American Psychiatric Association, 1980). Infusions of sodium lactate are considered a useful tool in investigating the possible causes of panic attacks. Although the mechanism of lactate’s effects is unclear (Ackerman and Sachar, 1974; Insel et al., 1984; Levin et al., 1984; Rainey et al., 1984b; Margraf et al., 1986), there is evidence that the incidence of lactate-induced panic attacks is much higher in patients prone to panic attacks than in normal controls (Pitts and McClure, 1967; Bonn et al., 197 I; Fink et al., 1971; Kelly et al., 1971; Applebyet al., 1981; Rifkinet al., 1981; Liebowitzetal., 1984; Raineyet al., 1984~. 1984b). Usually, patients reported higher anxiety levels and more anxiety symptoms with lactate than controls, and also showed higher autonomic arousal Anke Ehlers, Ph.D., Jiirgen Margraf, Dipl. Psych., Walton T. Roth, M.D., C. Barr Taylor, M.D., Richard J. Maddock, M.D., Javaid Sheikh, M.D., Maya L. Kopell, B.A., Kristin L. McClenahan. B.A., Denis Gossard, M.D., Geoffrey H. Blowers, Ph.D., W. Stewart Agras, M.D., and Bert S. Kopell. M.D., are in the Laboratory of Psychopharmacology and Psychophysiology, Veterans Administration Medical Center, Palo Alto, CA and the Laboratory for the Study of Behavioral Medicine, Stanford University Medical Center, Stanford, CA. (Reprint requests to Dr. W.T. Roth, Psychiatry (I 16A3), Palo Alto VA Medical Center. 3801 Miranda Ave., Palo Alto, CA 94304, USA.) 01651781/86/$03.50 0 1986 Elsevier Science Publishers B.V