Is the hierarchy necessary? Gradual versus variable exposure intensity in the treatment of unacceptable obsessional thoughts

Abstract Background and objectives Although research suggests that introducing varying levels of fear during exposure enhances outcomes for some anxiety-related problems, this has not been examined in the context of obsessions. The current preliminary study tested the hypothesis that introducing variability in exposure intensity would improve long-term outcomes relative to traditional gradual (hierarchical) exposure Methods Adults ( N  = 40) with a moderately distressing unacceptable obsessional thought were randomly assigned in parallel to four twice-weekly sessions of: (a) gradual exposure (EXP-G; n  = 19) emphasizing hierarchical exposure completion, or (b) variable exposure (EXP-V; n  = 21) emphasizing variability in exposure intensity Results There were no significant differences in pre to post changes between groups using self-report, interview, or behavioral outcomes (as evaluated by an independent assessor blind to treatment condition). Group comparisons at 3-month follow-up did not reach statistical significance but were moderate in magnitude. Specifically, as measured by clinical interview (the Yale-Brown Obsessive-Compulsive Scale; primary outcome) and self-report, individuals in the EXP-G group maintained gains at 3-month follow-up, while the EXP-V group continued to improve. Treatment expectancies and satisfaction were comparable for both groups. Five participants withdrew from the EXP-G condition, and none withdrew from the EXP-V condition. In contrast to previous studies, variability in subjective and physiological fear during exposure did not predict outcomes Limitations The study employed an analogue sample with moderate unacceptable obsessions, and results should be replicated in clinical samples Conclusions Variable exposure warrants future study to understand the mechanisms, moderators, and implications of this novel approach