The characteristics of unacceptable/taboo thoughts in obsessive–compulsive disorder

Abstract

Background

In the quest to unravel the heterogeneity of obsessive–compulsive disorder (OCD), an increasing number of factor analytic studies are recognising unacceptable/taboo thoughts as one of the symptom dimensions of OCD.

Aims

This study aims to examine the characteristics associated with unacceptable/taboo thoughts.

Methods

Using the Yale–Brown Obsessive–Compulsive Scale Symptom Checklist (YBOCS-SC) with 154 individuals with OCD, obsessive–compulsive symptoms were subjected to principal components analysis. The characteristics associated with the resulting symptom dimensions were then assessed using logistic and linear regression techniques.

Results

Unacceptable/taboo thoughts comprised of sexual, religious and impulsive aggressive obsessions, and mental rituals. Higher scores on an unacceptable/taboo thoughts symptom dimension were predicted by higher Y-BOCS obsession subscores, Y-BOCS time preoccupied by obsessions scores, Y-BOCS distress due to obsessions scores, importance of control of thought ratings, male gender, and having had treatment prior to entering into the study. Unacceptable/taboo thoughts were also predicted by greater levels of hostility, and a past history of non-alcohol substance dependence.

Conclusions

An unacceptable/taboo thought symptom dimension of OCD is supported by a unique set of associated characteristics that should be considered in the assessment and treatment of individuals with these symptoms.

Introduction

Unacceptable/taboo thoughts, also known as “pure obsessions”, refer to impulsive aggressive, sexual and religious obsessions. The observation that some obsessions occurred in the apparent absence of compulsions was first made by Baer [1] in a study employing factor analysis techniques. Since then, there have been a number of factor analytic studies [2], [3], [4], [5], [6], [7], [8], [9] that have revealed a symptom dimension of obsessive–compulsive disorder (OCD) characterised predominantly by obsessions and in particular aggressive, sexual and religious obsessions. More recently, studies [10], [11] have demonstrated that “pure obsessions” is a misnomer in that unacceptable/taboo thoughts tend to be accompanied by compulsions.

Unacceptable/taboo thoughts are distinctly ego-dystonic with a repugnant quality that tends not to be so prominent in other OCD symptoms [12]. As their name suggests, the content of these obsessions typically involves unacceptable, taboo or forbidden themes such as stabbing a relative, incest or blasphemy. Studies have associated unacceptable/taboo thoughts with mental rituals [10], reassurance-seeking [6], [10], avoidance [13], [14], good insight [15], male gender [16], [17], and being more likely to seek professional help [18].

In addition to the obvious phenomenological differences between unacceptable/taboo thoughts and other OCD symptoms, unacceptable/taboo thoughts also appear to have clinical utility as they have been associated with a differential response to treatment. Although studies examining the response of unacceptable/taboo thoughts to pharmacotherapy have resulted in conflicting findings [19], some studies investigating the response to behavioural interventions [20], [21], [22] have reported a poorer outcome.

This study aimed to illustrate that unacceptable/taboo thoughts are associated with different characteristics to other symptom dimensions of OCD and that these characteristics may have implications for the treatment of individuals with unacceptable/taboo thoughts. It was hypothesised that unacceptable/taboo thoughts would be associated with greater severity, specifically higher Y-BOCS obsession scores and higher levels of distress. These hypotheses were based on clinical observation and the findings of previous studies [23], [24]. Having hypothesized that greater degrees of severity and distress would be associated with unacceptable/taboo thoughts, it was additionally hypothesised that unacceptable/taboo thoughts would be associated with higher rates of having obtained treatment prior to entering the study, greater reassurance-seeking, greater levels of avoidance, higher rates of comorbid depression and stronger beliefs relating to a need to control one's thoughts. These hypotheses were based on limited evidence relating unacceptable/taboo thoughts to higher rates of previous treatment [18], greater reassurance-seeking [6], [10], greater levels of avoidance [13], [14], higher rates of comorbid depression [25], [26] and cognitive beliefs relating to the importance of controlling one's thoughts [27], [28], [29], [30].