This issue contains one review, on the endophenotype concept in psychiatric genetics. Three papers examine various aspects of post-traumatic stress disorder (PTSD), two use historical methods to address aspects of military psychiatry and dissociation, and five individual papers examine a variety of topics.

The idea that some phenotypes bear a closer relationship to the biological processes that give rise to psychiatric illness than diagnostic categories has attracted considerable interest. Much effort has been devoted to finding such endophenotypes, partly because it is believed that the genetic basis of endophenotypes will be easier to analyse than that of psychiatric disease. This belief depends in part on the assumption that the effect sizes of genetic loci contributing to endophenotypes are larger than those contributing to disease susceptibility, hence increasing the chance that genetic linkage and association tests will detect them. We examine this assumption by applying meta-analytical techniques to genetic association studies of endophenotypes. We find that the genetic effect sizes of the loci examined to date are no larger than those reported for other phenotypes. A review of the genetic architecture of traits in model organisms also provides no support for the view that the effect sizes of loci contributing to phenotypes closer to the biological basis of disease is any larger than those contributing to disease itself. While endophenotype measures may afford greater reliability, it should not be assumed that they will also demonstrate simpler genetic architecture.

Background. Childhood factors have been associated with increased risk of developing post-traumatic stress disorder (PTSD). Previous studies assessed only a limited number of childhood factors retrospectively. We examined the association between childhood neurodevelopmental, temperamental, behavioral and family environmental characteristics assessed before age 11 years and the development of PTSD up to age 32 years in a birth cohort.

Method. Members of a 1972–73 New Zealand birth cohort (n=1037) who were assessed at ages 26 and 32 years for PTSD as defined by DSM-IV.

Results. We identified two sets of childhood risk factors. The first set of risk factors was associated both with increased risk of trauma exposure and with PTSD assessed at age 26. These included childhood externalizing characteristics and family environmental stressors, specifically maternal distress and loss of a parent. The second set of risk factors affected risk for PTSD only and included low IQ and chronic environmental adversity. The effect of cumulative childhood factors on risk of PTSD at age 26 was substantial; over 58% of cohort members in the highest risk quartile for three developmental factors had PTSD as compared to only 25% of those not at high risk on any factors. Low IQ at age 5, antisocial behavior, and poverty before age 11 continued to predict PTSD related to traumatic events that occurred between the ages of 26 and 32.

Conclusions. Developmental capacities and conditions of early childhood may increase both risk of trauma exposure and the risk that individuals will respond adversely to traumatic exposures. Rather than being solely a response to trauma, PTSD may have developmental origins.

Background. Little is known about the correspondence between persistent self-reported disaster-related psychological problems and these problems reported by general practitioners (GPs). The aim of this study is to analyse this correspondence and to identify the factors associated with GPs' detection of persistent psychological problems.

Method. This study was conducted in a sample of 879 adult disaster-affected victims, taken from two longitudinal sources: the Enschede Firework Disaster Study and the GP-Monitor Study. Participants filled out a questionnaire 2–3 weeks and 18 months post-disaster and these data were combined with data from a GP-monitor collected up to 18 months post-disaster. The correspondence between persistent self-reported and GP-reported psychological problems was analysed with cross-tabulations. Logistic regression analyses were performed to identify variables which predicted GPs' detection of psychological problems.

Results. The correspondence rate among victims who visited their GP 18 months post-disaster was 60·4% for persistent intrusions and avoidance reactions, 72·6% for persistent general psychological distress and less than 20% for persistent depression and anxiety symptoms or sleep disturbances. Characteristics that predict GPs' identification of post-traumatic reactions or psychological distress were the level of self-reported post-traumatic symptoms/mental health, the number of contacts the victims had with their GP and the level of the victims' disaster-related experiences.

Conclusions. In general, there is a considerable correspondence between GP-reported and persistent self-reported incidences of post-traumatic stress and general psychological distress in disaster-affected victims. However, the correspondence declines in the case of more specific psychological symptoms.

Background. Brief interventions are needed in dealing with traumatic stress problems in large survivor populations after devastating earthquakes. The present study examined the effectiveness of a single session of exposure to simulated tremors in an earthquake simulator and self-exposure instructions in reducing post-traumatic stress disorder (PTSD).

Method. Participants were consecutively recruited from among survivors screened during field surveys in the disaster region in Turkey. Thirty-one earthquake survivors with PTSD were assigned either to a single session of behavioural treatment (n=16) or to repeated assessments (RA; n=15). Assessments in the treatment group were at 4, 8, 12, 24 weeks and 1–2 years post-treatment. The RA cases were assessed at baseline and 4 and 8 weeks after trial entry, after which they received the same treatment and were followed up at 4, 12, 24 weeks and 1–2 years.

Results. Between-group treatment effects at week 8 were significant on measures of fear, PTSD and self- and assessor-rated global improvement. Improvement rates were 40% at week 4, 72% at week 12, 80% at week 24, and 80% at 1–2-years' follow-up, with large effect sizes on fear and PTSD measures. Post-session reduction in fear of earthquakes and increased sense of control over fear at follow-up related to improvement in PTSD.

Conclusion. The study provided further evidence of the effectiveness of a single session of behavioural treatment in reducing fear and PTSD in earthquake survivors. Future research needs to examine the usefulness of earthquake simulators in increasing psychological preparedness for earthquakes.

Background. ‘Forward psychiatry’ was introduced by the French Army in 1915 to stem the loss of troops to base hospitals. Also known by the acronym PIE (proximity to the battle, immediacy of treatment and expectancy of recovery, including return to duty), it was subsequently used by the British and Americans in both World Wars. The US Army used PIE techniques in Korea and Vietnam. Although widely accepted as an effective intervention, forward psychiatry is not amenable to random-controlled trials and only one controlled outcome study has been conducted.

Method. All 3580 soldiers with shell shock admitted to 4 Stationary Hospital between January and November 1917 were recorded. Unit details, military experience, length of stay and outcomes were analysed. Soldiers were categorized into combat, combat-support and non-combatant groups. Admissions were correlated with military operations to compare the impact of defensive and offensive phases of warfare.

Results. Rates of admission for shell shock rose significantly during offensives when physical casualties escalated. Combat troops were disproportionately represented. Over 50% of admissions had less than 9 months service in France and 21% broke down within 3 months of going overseas. Less than 20% returned directly to combat units, most going to other hospitals, convalescent depots or base duties.

Conclusions. Forward psychiatry was not effective in returning combat troops to fighting units but, by allocating soldiers to support roles, it prevented discharge from the armed forces. Uncertainties remain about relapses, including other routes that servicemen used to escape from a combat zone.

Background. Natural human psychological phenomena, such as depression, anxiety, delusions, hallucinations and dementia, are documented across the ages in both fictional and non-fictional works. We asked whether ‘dissociative amnesia’ was similarly documented throughout history.

Method. We advertised in three languages on more than 30 Internet web sites and discussion groups, and also in print, offering US$1000 to the first individual who could find a case of dissociative amnesia for a traumatic event in any fictional or non-fictional work before 1800.

Results. Our search generated more than 100 replies; it produced numerous examples of ordinary forgetfulness, infantile amnesia and biological amnesia throughout works in English, other European languages, Latin, Greek, Arabic, Sanskrit and Chinese before 1800, but no descriptions of individuals showing dissociative amnesia for a traumatic event.

Conclusions. If dissociative amnesia for traumatic events were a natural psychological phenomenon, an innate capacity of the brain, then throughout the millennia before 1800, individuals would presumably have witnessed such cases and portrayed them in non-fictional works or in fictional characters. The absence of cases before 1800 cannot reasonably be explained by arguing that our ancestors understood or described psychological phenomena so differently as to make them unrecognizable to modern readers because spontaneous complete amnesia for a major traumatic event, in an otherwise lucid individual, is so graphic that it would be recognizable even through a dense veil of cultural interpretation. Therefore, it appears that dissociative amnesia is not a natural neuropsychological phenomenon, but instead a culture-bound syndrome, dating from the nineteenth century.

Background. Memory functioning has been highlighted as a central issue in pathological dissociation. In non-pathological dissociation, evidence for enhanced working memory has been found, together with greater task-load related activity. So far, no imaging studies have investigated working memory in dissociative patients.

Method. To assess working memory in dissociative patients functional magnetic resonance imaging was used during performance of a parametric, verbal working-memory task in patients with a dissociative disorder (n=16) and healthy controls (n=16).

Results. Imaging data showed that both groups activated brain regions typically involved in working memory, i.e. anterior, dorsolateral and ventrolateral prefrontal cortex (PFC), and parietal cortex. Dissociative patients showed more activation in these areas, particularly in the left anterior PFC, dorsolateral PFC and parietal cortex. In line with these findings, patients made fewer errors with increasing task load compared to controls, despite the fact that they felt more anxious and less concentrated during task performance.

Conclusions. These results extend findings in non-pathological high dissociative individuals, suggesting that trait dissociation is associated with enhanced working-memory capacities. This may distinguish dissociative patients from patients with post-traumatic stress disorder, who are generally characterized by impaired working memory.

Background. There is increasing evidence that subthreshold forms of psychopathology are both common and clinically relevant. To enable classification of these subthreshold forms of psychopathology, it may be useful to distinguish not only a threshold for illness but also for health. Our aim was to investigate this with regard to panic.

Method. Data were derived from the Netherlands Mental Health Survey and Incidence Study (NEMESIS), which is based on a large representative sample of the adult general population (18–65 years) of The Netherlands (n=7076). The Composite International Diagnostic Interview was used as a diagnostic instrument. By defining two thresholds, three groups were formed: panic disorder, subthreshold panic disorder and no-panic. These groups were compared using multinomial regression analysis, χ2 and analysis of variance.

Results. The 12-month prevalence of panic disorder was 2·2% while that of subthreshold panic disorder was 1·9%. Symptom profiles and risk indicators associated with panic disorder and subthreshold panic disorder were similar, and half of the risk indicators were more strongly associated with panic disorder than with subthreshold panic disorder. Subthreshold panic disorder occupied an intermediate position between panic disorder and no-panic with regard to the number of symptoms, the percentage of subjects with co-morbidity, and functioning.

Conclusions. Subthreshold panic disorder is common, and seems clinically relevant, but is milder than panic disorder. These results thus support the use of a double threshold in panic. Further research should focus on the positioning of the thresholds, the course of subthreshold panic disorder and its treatment options.

Background. Neuroticism is widely used as an explanatory concept in etiological research of psychopathology. In order to clarify what neuroticism actually represents, we investigated the genetic association between neuroticism and cardiovascular measures.

Method. In 125 female twin pairs (18–30 years), electrocardiogram and continuous finger blood pressure were assessed during two rest and two mental stress conditions. Mean values for baroreflex sensitivity (BRS), heart rate variability (HRV) and inter-beat interval (IBI) were calculated for each condition. Neuroticism was assessed by multiple questionnaires. Multivariate genetic model-fitting analyses were used to investigate the genetic correlation between latent neuroticism and the cardiovascular autonomic nervous system (ANS) measures.

Results. Neuroticism was negatively correlated to BRS and HRV. Neuroticism was not correlated to IBI. For BRS, this phenotypical relation was entirely determined by shared genetic influences. For HRV, the genetic contribution to the phenotypical correlation was not significant, but the proportions of explained covariance showed a trend of more genetic than environmental influences on the phenotypical relationship.

Conclusions. High neuroticism is associated with a deregulated ANS. Pleiotropic genetic effects may be partly responsible for this effect.

Riese, H., Rosmalen, J. G. M., Ormel, J., Van Roon, A. M., Oldehinkel, A. J. & Rijsdijk, F. V. The genetic relationship between neuroticism and autonomic function in female twins. Psychological Medicine. Published online 9 November 2006. doi:10.1017/S0033291706009160.

Background. Previous studies suggest that idiopathic environmental intolerance (IEI) is a variant of somatoform disorders (SFDs) or the so-called functional somatic syndromes. Little is known, however, about the stability and the psychological predictors of IEI.

Method. This prospective study examined the 1-year stability of somatic symptoms and IEI features in three diagnostic groups: 49 subjects with IEI, 43 subjects with SFD but without IEI, and 54 subjects (control group, CG) with neither IEI nor SFD. The predictive value of typical psychological predictors for somatization was tested using zero-order correlations and multiple linear regression analyses.

Results. Somatic symptoms and IEI features proved to be temporally stable over the 1-year follow-up period. The SFD and IEI groups scored significantly higher than CG on all measures of somatic symptoms and on questionnaires assessing psychological predictors for somatization. Measures of trait negative affectivity (NA), somatic symptom attribution and somatosensory amplification predicted somatic symptom severity within the IEI and SFD groups, both at baseline and 1 year later. The strongest predictors of IEI complaints in the IEI group were somatic attributions, followed by prominent cognitions of environmental threat and a tendency to focus on unpleasant bodily sensations and to consider them as pathological.

Conclusions. IEI and SFD are highly stable conditions. In both SFD and IEI, NA and the processes of symptom perception, interpretation and attribution contribute substantially to the persistence of typically somatoform symptoms and IEI complaints. Treatment of IEI and SFD should address these psychological factors and mechanisms.

Background. Somatizing patients are a challenge to general practitioners (GPs). A cluster randomized controlled trial was conducted to asses the effect of specific communication techniques delivered by GPs on somatizing patients' self-perceived health.

Method. Thirty-nine GPs were assigned randomly to two parallel groups. GPs in the intervention group treated somatic patients according to specific communication techniques focused on offering a physical explanation – release of hormones – and approaching sensitive topics in the patient's experience indirectly. Control GPs used the standard Goldberg reattribution technique. A total of 156 patients, aged 18–65 years, were selected randomly from a list of 468 patients with six or more active symptoms for women and four or more for men. All patients had six programmed 30-min consultations. Health-related quality of life (assessed with the 36-item Short-Form Health Survey, SF-36) and a summary utility index were used as outcome measures. Patients were interviewed at home at baseline and at 3, 8 and 12 months after the beginning of the intervention.

Results. Patients in both groups improved in all dimensions of the SF-36. The time course of the quality of life was significantly better for the intervention group in five of the eight scales of the SF-36 (bodily pain, mental health, physical functioning, vitality, and social functioning) and in the utility index (p<0·039).

Conclusions. Communication techniques were found to have a clinically relevant impact on body pain. This finding, together with a trend towards better scores in the remaining scales, justifies the use of these techniques in psychosocial interventions delivered to patients with medically unexplained symptoms.

The Nancy Lurie Marks Family Foundation announces the availability of research funds for projects aimed at investigating communication difficulties, capacities and options for individuals with autism spectrum disorders. Although communication impairment is at the core of the autism syndrome, relatively little scientific attention has been focused on addressing this critical area.