title: Effects of Lorazepam and citalopram on human defensive reactions: ethopharmacological differentiation of fear and anxiety.
abstract: Drugs that are clinically effective against generalized anxiety disorder preferentially alter rodent risk assessment behavior, whereas drugs that are clinically effective against panic disorder preferentially alter rodent flight behavior. The theoretical principle of "defensive direction" explains the pattern of associations between emotion and defensive behavior in terms of the differing functional demands arising from cautious approach to threat (anxiety) versus departure from threat (fear), offering the prospect that clinically important emotions may be explained using a single rubric of defense. We used a within-subjects, placebo-controlled, design to test this theory, measuring the effects of citalopram and lorazepam on the defensive behavior of 30 healthy adult male humans. We indexed human defensive behavior with a translation of an active avoidance task used to measure rodent defense and found that lorazepam significantly reduced the intensity of defensive behavior during approach to threat (hypothetically anxiety-related) but not departure from threat (hypothetically fear-related). Contrary to prediction, citalopram did not affect either form of defensive reaction. Since lorazepam is a drug with well established anxiety reducing properties, these data support the hypothesis that anxiety is an emotion elicited by threat stimuli that require approach. These data also contribute to the validation of a novel human analog of an established experimental model of rodent fear and anxiety.
authors.affiliation: Centre for Neuroimaging Sciences, Institute of Psychiatry, London SE5 8AF, UK. Adam.Perkins@kcl.ac.uk
authors.forename: Adam M
authors.initials: AM
authors.lastname: Perkins
authors.forename: Ulrich
authors.initials: U
authors.lastname: Ettinger
authors.forename: Robert
authors.initials: R
authors.lastname: Davis
authors.forename: Russell
authors.initials: R
authors.lastname: Foster
authors.forename: Steven C R
authors.initials: SC
authors.lastname: Williams
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Corr
mesh_terms: D000328:Adult; D014151:Anti-Anxiety Agents / Q000494:pharmacology; D018687:Antidepressive Agents, Second-Generation / Q000494:pharmacology; D001007:Anxiety / Q000208:ethnology* / Q000523:psychology; D001362:Avoidance Learning / Q000187:drug effects; D015283:Citalopram / Q000494:pharmacology*; D004311:Double-Blind Method; D004924:Escape Reaction / Q000187:drug effects*; D005239:Fear / Q000187:drug effects*; D006801:Humans; D008140:Lorazepam / Q000494:pharmacology*; D008297:Male; D010551:Personality; D018570:Risk Assessment; D013647:Task Performance and Analysis; D055815:Young Adult
chemical_list: D014151:Anti-Anxiety Agents; D018687:Antidepressive Agents, Second-Generation; D015283:Citalopram; D008140:Lorazepam