Invited essay: Cognitive influences on the psychological immune system.

The construct of the psychological immune system is described and analysed. The direct and indirect cognitive influences on the system are discussed, and the implications of adding a cognitive construal to the influential model of a behavioural immune system are considered. The psychological immune system has two main properties: defensive and healing. It encompasses a good amount of health-related phenomena that is outside the scope of the behavioural model or the biological immune system. Evidence pertaining to the psychological immune system includes meta-analyses of the associations between psychological variables such as positive affect/wellbeing and diseases and mortality, and associations between wellbeing and positive health. The results of long-term prospective studies are consistent with the conclusions drawn from the meta-analyses. Laboratory investigations of the effects of psychological variables on the biological immune system show that negative affect can slow wound-healing, and positive affect can enhance resistance to infections, for example in experiments involving the introduction of the rhinovirus and the influenza A virus. A number of problems concerning the assessment of the functioning of the psychological immune system are considered, and the need to develop techniques for determining when the system is active or not, is emphasized. This problem is particularly challenging when trying to assess the effects of the psychological immune system during a prolonged psychological intervention, such as a course of resilience training.

Imagery in mental contamination.

BACKGROUND: Intrusive imagery is experienced in a number of anxiety disorders, including Obsessive Compulsive Disorder (OCD). Imagery is particularly relevant to mental contamination, where unwanted intrusive images are hypothesized to evoke feelings of dirtiness and urges to wash (Rachman, 2006). AIMS: The aim of this study was to examine the nature of imagery associated with mental contamination. METHOD: Fifteen people with contaminated-based OCD completed a semi-structured imagery interview designed specifically for this study. RESULTS: Ten participants reported images associated with contamination. These images were vivid and distressing and evoked feelings of dirtiness. Participants engaged in a number of behaviours to neutralize their images, including compulsive washing. A small number of participants also reported images that protected them from contamination. CONCLUSIONS: In support of the theory of mental contamination (Rachman, 2006), images can lead to feelings of pollution and compulsive washing. Further research is needed to explore the role of imagery in maintaining contamination fears.

The spread of mental contamination.

BACKGROUND AND OBJECTIVES: Fear of contamination can be evoked following physical contact with a dirty, harmful or polluted item, person, or place (contact contamination) or in the absence of physical contact with a contaminant (mental contamination). The spread of contact contamination does not degrade over successive degrees of removal from the contaminated source. However, to date, the spread of mental contamination has not been empirically investigated. This study aimed to examine the spread and degradation of mental contamination. METHODS: The paradigm of Tolin et al. (2004) was adapted. Feelings of mental contamination were evoked, and participants were asked to transfer these feelings to an uncontaminated pencil by touching it (contact condition) and without touching it (no contact condition). RESULTS: Seventy-two percent of participants in the contact condition and 48% participants in the no-contact condition reported being able to transfer contamination to a clean pencil, demonstrating that mental contamination transfers both with and without contact. In both conditions, the mental contamination subsequently spread to a series of 12 neutral pencils without degradation. CONCLUSIONS: These findings suggest that mental contamination can be transmitted and spread in the absence of physical contact, similar to contact contamination.

The spontaneous decay and persistence of mental contamination: an experimental analysis.

BACKGROUND AND OBJECTIVES: It has recently been identified that feelings of contamination can arise in the absence of physical contact with a stimulus. This concept, known as 'mental contamination' has particular relevance to Obsessive Compulsive Disorder in which compulsive cleaning is a common symptom presentation. Experimental studies have begun to examine the psychopathology of mental contamination. The aims of the two experiments reported here were to explore the evocation and spontaneous decay of mental contamination. METHODS: In Experiment 1, a variant of the autobiographical memory task was used in which 40 non-clinical participants were asked to recall autobiographical memories associated with betrayal, harm, humiliation and violation of moral standards. In Experiment 2, 60 participants with moderate levels of mental contamination were asked to complete five short tasks designed to induce mental contamination, including recalling unwanted memories and images. RESULTS: In both experiments, participants reported significant increases in mental contamination, anxiety, urges to wash and actual washing behaviour. In experiment 1, the effect of the induction decayed spontaneously. Experiment 2 found that re-evoking contamination and repeated washing led to the persistence of mental contamination. LIMITATIONS: The studies were conducted on non-clinical samples. CONCLUSIONS: These findings demonstrated that repeated triggers may be causally connected to the maintenance of mental contamination fears in non-clinical samples.

Treatment of obsessions: a randomized controlled trial.

This study tested Rachman's cognitive behavioral method for treating obsessions not accompanied by prominent overt compulsions. The cognitive behavioral treatment was compared to waitlist control and an active and credible comparison of stress management training (SMT). Of the 73 adults who were randomized, 67 completed treatment, and 58 were available for one-year follow-up. The active treatments, compared to waitlist, resulted in substantially lower YBOCS scores, OCD-related cognitions and depression as well as improved social functioning. Overall, CBT and SMT showed large and similar reductions in symptoms. Pre-post effect sizes on YBOCS Obsessions for CBT and SMT completers was d = 2.34 and 1.90, respectively. Although CBT showed small advantages over SMT on some symptom measures immediately after treatment, these differences were no longer apparent in the follow-up period. CBT resulted in larger changes on most OCD-related cognitions compared to SMT. The cognitive changes were stable at 12 months follow-up, but the differences in the cognitive measures faded. The robust and enduring effects of both treatments contradict the long-standing belief that obsessions are resistant to treatment.

Stimulus estimation and the overprediction of fear.

Overprediction of fear is the tendency to overestimate the amount of fear that one will experience in a subjectively threatening situation. Little is known about this bias, despite the important role it appears to play in producing phobic avoidance. The present study proposed a stimulus estimation hypothesis of overprediction, which states that overprediction of fear arises from the overprediction of the danger features of the feared stimulus and the underprediction of safety features. This model was supported by the results of structural equation modelling based on the responses of 224 snake-fearful subjects exposed to a live harmless snake. The determinants of the stimulus estimation bias are considered and directions for further investigation are discussed.

The effects of blood sugar level changes on cognitive function, affective state, and somatic symptoms.

In an attempt to find out whether decreased blood sugar level is associated with impaired cognitive function, adverse emotional changes, or somatic symptoms, 35 subjects who suspected that they had hypoglycemia were given 5-hr glucose tolerance tests (GTTs). Nine blood samples were taken during the GTT, and the subject's mood, Serial Sevens Test (SST) performance, and somatic symptom reports were recorded on each occasion of sampling. The subjects reported significantly more negative affect and somatic symptoms after glucose nadir than before nadir. SST performance deteriorated at glucose nadir. These effects were more pronounced for subjects with high hypoglycemic index scores than for subjects with low index scores. The impairment in SST performance was greater for subjects who showed rapid decreases in blood sugar than for subjects who showed slow decreases. Dividing subjects by high and low nadirs did not reveal any differences in symptomatology.

Return of fear: perceived skill and heart-rate responsivity.

The hypothesis that high heart rate and low perceived skill would be associated with greater return of fear than low heart rate and high perceived skill was investigated in a group of 63 anxious musical performers. Musicians were taught progressive muscle relaxation and attention-focusing skills over the course of four weekly sessions. Return of subjective fear was assessed between training programme sessions and at a three-month follow-up assessment. Performance quality ratings served as the behavioural measure, anticipatory heart rate as the physiological measure, and subjective units of distress scales as the subjective measure. Four classification groups (high heart rate, low perceived skill; high heart rate, high perceived skill; low heart rate, low perceived skill; and low heart rate, high perceived skill) were formed on the basis of median splits of heart rate and perceived skill pre-assessment levels. Each group demonstrated subjective fear reduction, while heart rate reduced in the high heart-rate subjects, and performance quality improved overall at post-assessment. Follow-up return of fear was apparent in high heart-rate subjects, regardless of their perceived skill status. High heart-rate subjects reported more anxious thoughts than did low heart-rate subjects. Perceived skill was not clearly associated with return of fear. Post-hoc comparisons indicated that subjects who demonstrated follow-up return of fear had higher heart rate, lower perceived skill, more anxious thoughts, less performance skill and fewer performances over the follow-up interval than subjects who did not demonstrate a return of fear. However, initial heart rate was the only significant predictor of follow-up fear levels.