Personality style, cortisol secretion and the inflammatory response to trauma exposure in a cohort of South African metro police cadets: a prospective, longitudinal study
Date
2012-01-17
Authors
Subramaney, Ugasvaree
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Abstract
Literature investigating trauma exposure, Posttraumatic stress disorder (PTSD) and
cortisol secretion has produced conflicting results with regard to whether cortisol is
increased or decreased. With trauma there is also a pro- inflammatory response which
is intimately linked with the hypothalamic pituitary axis (HPA). The police population can
offer useful information in this regard as they represent a sample that will undergo
exposure to traumatic events as part of their normal duties. In South Africa few studies
have examined biological correlates of the traumatic stress response in the police
population.
This study sought to determine whether correlations exist between cortisol and the
inflammatory response in terms of the cytokines Interleukin 6 (IL6) and Tumour Necrosis
Factor (TNF) in response to trauma exposure in a cohort of newly enrolled metro police
officers, previously naïve to the duty related trauma exposure. Personality styles were
assessed, as coping skills and personality have been suggested as factors determining
responses to trauma.
The study participants were followed up for one year with repeated measures analysis of
urine, blood, and saliva cortisol as well as blood cytokine determination every 3 months.
Measures for PTSD [the Clinician Administered Scale for Posttraumatic stress disorder
(CAPS) and the revised version of the Impact of Event Scale (IES-R)] as well as for
depression [the Hamilton Depression Rating Scale (HAM-D)] were undertaken.
145 new recruits volunteered for the study, of which 120 completed all 5 visits. There
were slightly more females than males in the sample and almost 50% of the sample admitted to alcohol abuse. Trauma exposure on entry into the police force was
remarkably high with 99% having been exposed to at least one traumatic event in their
lives. The majority (61.1 %) had been exposed to more than one traumatic event. There
was evidence for the influence of prior trauma on responses to current traumatic events.
MVA’s were very common, both duty and non duty related. Certain traumas were
associated with greater changes in scores for PTSD and depression in relation to
baseline. Over the 5 visits, only a third submitted valid 24 hour urine samples. Of these,
the profile of the entire group indicated that 24 hour urine cortisol tended to initially
decrease, and then increase with time. Saliva and blood cortisol, which were more
reliably measured, tended to decrease with time.
Scores for depression and post traumatic stress disorder were generally low in response
to duty related traumatic events, and tended to decrease over time. However, the
prevalence of lifetime PTSD as measured by the CAPS was high.
There was a strong linear correlation between TNF and IL6. Results indicate a
proinflammatory response, particularly with regard to IL6. There were no significant
correlations between blood cortisol and HAM-D and between blood cortisol and CAPS
(lifetime). There was an inverse relationship between CAPS (current scores) and blood
cortisol. Cortisol and IES-R scores were significant at visit 3 (inverse relationship). For
saliva, there were no significant associations with any of the variables for PTSD and
depression.
For personality styles, aggressive and antisocial clinical patterns were associated with
lower current CAPS scores, while schizoid clinical pattern and the severe syndrome
scale of thought disorder showed an association with lower lifetime CAPS score. For the
IES-R, only narcissistic clinical pattern was associated with lower scores. A further analysis of those with low (less than 25% of the median) and high (greater than 25% of
the median) cortisol responses was undertaken.
The results indicate a similar trend to some studies showing lowered cortisol levels with
chronic trauma exposure, but this did not correlate with sufficiently high scores for PTSD
as measured by the CAPS. Similarly, proinflammatory cytokine increases are evident
with trauma exposure, but not with scores for PTSD and depression. There were more
variables significantly associated with the low cortisol responders than the high cortisol
responders; with a suggestion of cumulative trauma exposure correlating with low
cortisol response and a corresponding pro inflammatory response in terms of IL6.
The results are discussed with a view to assisting the metro police force with recruitment
and counseling strategies and important future research is recommended.