Neuropsychological Mechanisms of Intrusive Thinking

A classic definition of intrusive thinking is “any distinct, identifiable cognitive event that is unwanted, unintended, and recurrent. It interrupts the flow of thought, interferes in task performance, is associated with negative affect, and is difficult to control” (Clark 2005:4). While easy to understand and applicable to many cases, this definition does not seem to encompass the entire spectrum of intrusions. For example, intrusive thoughts may not always be experienced as unpleasant or unwanted, and may in some situations even be adaptive. This chapter revisits the definition of intrusive thinking, by systematically considering all the circumstances in which intrusions might occur, their manifestations across health and disorders, and develops an alternative, more inclusive definition of intrusions as being “interruptive, salient, experienced mental events.” It proposes that clinical intrusive thinking differs from its nonclinical form with regard to frequency, intensity, and maladaptive reappraisal. Further, it discusses the neurocognitive processes underlying intrusive thinking and its control, including memory processes involved in action control, working memory and long-term memory encoding, retrieval, and suppression. As part of this, current methodologies used to study intrusive thinking are evaluated and areas are highlighted where more research and/or technical innovation is needed. It concludes with a discussion of the theoretical, therapeutic, and sociocultural implications of intrusive thinking and its control