Servicio de Información Comunitario sobre Investigación y Desarrollo - CORDIS

Final Report Summary - PBPTSD (Psychobiology of posttraumatic stress disorder)

The general objective of the project PBPTSD was to contribute to understanding of the Posttraumatic stress disorder (PTSD), its characteristics, subtypes, and risk factors in order to help improve its diagnosing and prevention. The study was designed to investigate the inner architecture of PTSD in terms of (some of the) supposedly relevant psychological, biochemical, endocrinological, genetic, physiological and anthropometric variables/parameters.

More specifically, the scientific objectives were to explore the following:
1. Psychological parameters in PTSD:
- basic personality traits (big five and behavioral disintegration)
- memory performance, intelligence, and executive functions
- overall psychiatric symptoms;
2. Biological parameters in PTSD:
- anthropometric status
- metabolic status
- HPA-axis function
- endogenous opiate system
- sleep status;
3. Relations among the above mentioned biological and psychological parameters in health and PTSD

The results of the study are intended to be used for:
a. assessment of risk;
b. providing brief assessment of PTSD symptomatology; and
c. improve the diagnosis of PTSD.

The male subjects underwent simultaneous psychological and biological measurements (Serbia), while the female subjects (Croatia) participated only in psychological part of the study.

Subjects that were recruited in Serbia mostly came from the Belgrade region. All subjects were hospitalised for three days for the acquisition of the parameters and were thus standardised. Biological measurements included variables related to Hypothalamo-pituitary-adrenocortical (HPA) axis (including cortisol receptor and its gene polymorphism), anthropometry, body composition, lipid status, insulin resistance, and sleep and dream disturbances (nightmares). This included blood draws from an i.v. line on 13 time points (starting 2 200 h) with one hour intervals. All subjects received 0.5 mg dexamethasone at 2 300 h. Psychological and symptoms assessment were performed at discrete intervals and encompassed symptom The advantage of this study is that a large number of variables was measured on one and the same subject (on approx 400 male subjects - the whole set of biological and psychological variables), so that they can be cross-correlated. All data are collected in one database and are being analysed by advanced statistical methods. The database contains over 3 600 variables, directly measured or derived assessment, personality inventories, and life experiences.

Mastering different advanced statistical techniques enable us to examine the correlations between complex variables, i.e. linear combinations of the variables.

Canonical discriminant analysis showed that neuroticism from NEO-PI and disintegration (as primary constituents of the first discriminative function in the personality space) discriminate, primarily, current PTSD patients from all other groups, thus composing the main component of our screening and risk batteries. This analysis also revealed that the level of general neurocognitive functioning is lower in both PTSD groups than in control groups (resilient and healthy). Further finding suggests that self-control and superior executive functioning define the individual resilience capacity in situations of extreme stressor exposure.

It seems that biological variables generally have larger intra-group variance, so it is more difficult to detect differences among groups. For example, a comprehensive set of measurements done on lymphocyte cortisol receptors did not show any intergroup differences. Although negative, this result is very significant because, due to the large sample on which it is obtained, adds considerable weight to the side with the same finding in the ongoing scientific debate. This debate involved several teams (and noteworthy material resources), but all those studies were done on far smaller samples. No inter-group differences in mean cortisol values (obtained from 13 night measurements) could be seen in the same light (of huge intra group differences).

But, analysis of low dose (0.5 mg) dexamethasone suppression test data revealed that hypersuppression of cortisol is higher in PTSD patients (this result also confirms one side in the mentioned debate). Significant correlations of cortisol-related variables with personality variables are also found, but this line of analyses needs further, more detailed work. One of the objectives of the study was to use the findings as a basis for improving PTSD screening, diagnosing and risk factors assessing. This has been achieved by developing combined psycho-biological batteries and by improving psychological instruments for measuring PTSD:

a. Risk assessment
As preliminary data-analyses suggested, the risk batteries should comprise measurements of personality traits and neurocognitive functioning. Although the design of the study does not unambiguously allow ascribing the empirically found differences to predisposing factors, there is independent empirical evidence that emphasises this conclusion.

Having in mind the number and comprehensiveness of variables in the study, it would further contribute to a more precise definition of these factors, as well as to assessing their relative contribution to PTSD. Apart from neuroticism, our study did reveal an independent important contribution of disintegration in explaining variance in PTSD. Analysis of neurocogntive data pointed to the independent importance of intellectual factors and executive functions in understanding PTSD. Higher level of intelligence and memory functioning seemed to represent basic neurocognitive factors protecting against developing PTSD after the traumatic event, while superior executive functioning seems to reflect additional capacity for resilience. Precise composition of batteries for risk assessment will be a matter of further, more elaborated analyses of the data.

b. Brief assessment of PTSD symptomatology
Brief assessment of PTSD symptomatology can be done by 22-items IES-R, a standard instrument for the assessment of posttraumatic symptomatology, followed by SRD-10, the 10-items instrument for measuring dissociative symptomatology. IES-R is the most frequently used self-report instrument for the assessment of PTSD in the region of former Yugoslavia, so the norms for various types of vulnerable groups could be easily established. Apart from this, even the cut-off score on IES-R, which enables making tentative diagnosis of PTSD has been already established.

This study opens a new possibility for extracting the combination of a small number of symptoms that not only detect PTSD efficiently, but also help extract additional information about whether the person is prone to recover or to develop chronic PTSD.

c. Improvement in diagnosing PTSD
This section was a matter of more thorough analyses that will include the integration of empirical data from numerous previous studies done by the same research group.

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