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Jonathan Bisson is a clinical senior lecturer in psychiatry at Cardiff University (Monmouth House, University Hospital of Wales, Heath Park, Cardiff CF14 4XW, UK. Email: bissonji{at}cf.ac.uk). He leads the local traumatic stress service and is an active researcher in this field. He was recently co-chair of the Guideline Development Group for the National Institute for Clinical Excellences clinical practice guidelines on post-traumatic stress disorder.
| Abstract |
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Factors associated with the development of PTSD include lack of perceived social support after the event, marked initial distress, high-impact trauma (rape has consistently been associated with the highest rates), dissociation at the time, past psychiatric history and female gender (Brewin et al, 2000; Ozer et al, 2003). Over half of PTSD sufferers will also have another psychiatric disorder (Kessler et al, 1995). As a diagnosis, PTSD has always been associated with a degree of controversy. Some have criticised the very existence of PTSD, arguing that it is a Western social construct; others acknowledge its existence but are concerned by probable over-diagnosis (e.g. Tyrer, 2005).
Aside from the controversy over the diagnosis of PTSD, its management has also been controversial. Interest in the prevention of its development following a traumatic event provoked attempts to discover effective early psychological interventions. One of these, psychological debriefing, has now been shown to lack evidence of efficacy (Rose et al, 2005) but trauma-focused cognitivebehavioural interventions for symptomatic individuals have been shown to be efficacious (e.g. Bryant et al, 1998; Ehlers et al, 2003; Bisson et al, 2004).
Of more pertinence here is the possibility of a new area of controversy in the management of PTSD, that of the effectiveness or otherwise of pharmacological approaches. Clinical practice guidelines commissioned by the National Institute for Health and Clinical Excellence (NICE) recommend that medication should be considered a second-line treatment for PTSD, behind trauma-focused psychological treatments such as trauma-focused cognitivebehavioural therapy and eye movement desensitisation and reprocessing (National Collaborating Centre for Mental Health, 2005). My primary aim in this article is to critically review the evidence for a pharmacological approach to the management of PTSD, to allow readers to understand the evidence on which the NICE guidelines have been based and draw their own conclusions regarding the role of medication in PTSD.
| The neurobiology of PTSD |
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Connections between the amygdala, hippocampus and medial prefrontal cortex have been implicated in determining the final fear response. Hippocampal lesions have been associated with a stronger fear response and smaller hippocampal volume has been associated with PTSD in several studies, probably representing a pre-existing vulnerability to its development rather than a neurotoxic consequence (Gilbertson et al, 2002). Neuroimaging studies of people with PTSD have shown decreased activity in medial prefrontal and anterior cingulate areas to be correlated with increased activity in the amygdala (Bremner et al, 1999; Shin et al, 2004). This has resulted in the proposal that PTSD represents a failure of medial prefrontal and/or anterior cingulate networks to regulate amygdala activity, resulting in hyperreactivity to threat (Bremner, 1999).
One of the most enduring neurophysiological theories in recent times has been that of enhanced negative feedback in the hypothalamicpituitaryadrenal axis. Several studies have found low cortisol levels in people with PTSD and an opposite response to the dexamethasone suppression test than that seen with severe depression, i.e. there is over-suppression of cortisol release. However, more recent studies have not consistently supported this finding (Young & Breslau, 2005). The finding of increased plasma catecholamine levels in PTSD sufferers has also evoked considerable interest, including the suggestion that an initial adrenergic (adrenaline and noradrenaline) surge may be associated with the laying down of traumatic memories (Pitman, 1989).
Our improved understanding of the neurobiology of PTSD does not appear to have driven most studies of the efficacy of pharmacological agents in the treatment of the disorder, but it has led to the development of hypotheses for the potential effectiveness of some drugs (for example propranolol and hydrocortisone as early interventions, see below). It has also resulted in attempts to determine the impact of drugs on the neurobiological processes themselves. Citalopram, for example, has now been shown to influence the acquisition of fear conditioning (Burghardt et al, 2004).
| Determining the efficacy of interventions |
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The efficacy of the drugs is described in terms of reduction in clinician-assessed severity of PTSD symptoms using the results of the NICE meta-analysis in this area (National Collaborating Centre for Mental Health, 2005). In studies that did not include a clinician-rated outcome measure the results of the Impact of Event Scale, a self-report measure, are given. Box 1
outlines the statistical terms used in the presentation of the results.
Box 1 Presentation of results
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| Prevention of PTSD |
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The second study concerned propranolol, a beta-blocker. It was based on the hypothesis that an adrenergic surge beginning almost immediately after a traumatic event is associated with the development of traumatic memories. Pitman and colleagues (2002) hypothesised that, for propranolol to be successful, individuals would have to start taking it within 6 h of the trauma. The logistic implications of running a trial with this constraint are daunting, but all credit to the researchers in completing a small study of individuals who were randomly allocated to receive 40 mg propranolol or a placebo four times a day for 10 days. There was no significant difference in rates of PTSD between the two groups at 1 month (k = 1; n = 41; RR = 1.14; 95% CI 0.552.35) or 3 months (k = 1; n = 41; RR = 1.28; 95% CI 0.692.38), with the trend being in favour of the placebo group. However, the propranolol group became less physiologically aroused when they listened to an account of the traumatic event, which indicates the possibility of some effect but not enough to recommend routine prescribing.
Finally, there has been one small RCT of temazepam given shortly after a traumatic event (Mellman et al, 2002). This is of interest because it has been argued that benzodiazepines may hinder the processing of trauma, but on closer scrutiny such assertions appear to be based more on anecdote and, possibly, an anti-prescribing stance than evidence. From a mean of 14 days after the trauma, individuals in the treatment arm received 30 mg temazepam daily for 5 days, then 15 mg daily for 2 days. There was no statistical difference in rates of PTSD at the 6-week follow-up point, although a trend was found in favour of the placebo group (k = 1; n = 22; RR = 3.2; 95% CI 0.5418.98). The temazepam group had slept significantly better on the first night, but there was no significant difference between groups at follow-up.
In summary, there is not enough evidence to advocate the routine prescription of medication to prevent PTSD. There is some evidence for intravenous hydrocortisone in people with septic shock, but clearly it is difficult to generalise these results to other populations. There is also some evidence that temazepam may help with acute insomnia following traumatic events. There has been no research to date exploring the potential of more commonly used agents such as antidepressants in the immediate or early aftermath of a traumatic event.
| Treatment of PTSD |
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Sertraline
One of the most interesting things about sertraline is that, although it is widely recommended as an effective treatment for PTSD (e.g. Friedman et al, 2000; Stein et al, 2004), PTSD is an indication for its use in the UK in females but not in males. This suggests that the data presented to the authorities were not totally convincing. In fact, the NICE figures from four published (Brady et al, 2000; Davidson et al, 2001a, 2006; Zohar et al, 2002) and two unpublished studies (Pfizer 588; Pfizer 589) just fail to achieve statistical significance, with a trend in favour of sertraline (k = 6; n = 1123; s.m.d. = 0.26; 95% CI 0.51 to 0.00). Interestingly, the Guideline Development Group was aware of the two unpublished studies of sertraline held by Pfizer (Pfizer 588; Pfizer 589). Despite several requests the full results were not forthcoming, although enough information was obtained to include the studies in the final meta-analysis (National Collaborating Centre for Mental Health, 2005: p. 71). The inclusion of these two studies reduced the apparent efficacy of sertraline. Such experiences encourage close scrutiny of efficacy claims and beg the question How many other unpublished trials are there?. Calls for the pre-registration of RCTs and an undertaking to place all results in the public domain seem to be well founded.
Fluoxetine
Fewer individuals have participated in fluoxetine trials than in trials for the other two SSRIs, and only one trial (Martenyi et al, 2002) used a standardised clinician assessment of the severity of PTSD symptoms as a primary outcome measure. The results are less convincing than those for paroxetine and do not reach statistical significance (k = 1; n = 301; s.m.d. = 0.28; 95% CI 0.54 to 1.2), but this may be explained by insufficient numbers to show a real but modest effect.
Tricyclics and monoamine oxidase inhibitors
The RCTs of tricyclic antidepressants and monoamine oxidase inhibitors (MAOIs) are older than those of SSRIs and their quality is inferior. It is disappointing that more trials have not been carried out, particularly given the encouraging results of those that have been published. None of the trials used a clinician-rated outcome measure and therefore the results of the Impact of Event Scale, a self-report measure, are given.
Amitriptyline
The one study (Davidson et al, 1990) that considered the efficacy of amitriptyline was positive but with very large confidence intervals, meaning that its true effect could be anything between low and very large (k = 1; n = 33; s.m.d. = 0.9; 95% CI 1.62 to 0.18).
Imipramine
The evidence for imipramine (Kosten et al, 1991) is weaker than that for amitriptyline and the effect does not achieve statistical significance, although the wide confidence intervals mean that its true effect could be a positive one (k = 1; n = 41; s.m.d. = 0.24; 95% CI 0.86 to 0.38).
Phenelzine
Phenelzine is the only available MAOI with an evidence base for the treatment of PTSD (Kosten et al, 1991) and, like amitriptyline, although the true magnitude of its effect is not known it appears to be efficacious (k = 1; n = 37; s.m.d. = 1.08; 95% CI 1.75 to 0.36).
Other drugs
Mirtazapine
There has been one small RCT (Davidson et al, 2003) of mirtazapine which was strongly in favour of the drug (k = 1; n = 21; s.m.d. = 1.89; 95% CI 3.00 to 0.78). It is important to be cautious when interpreting the true effect of any intervention on the basis of one small RCT, but these results suggest that mirtazapine is worthy of further investigation.
Venlafaxine
The results of the single relatively large RCT of venlafaxine (Davidson et al, 2006) were disappointing and did not achieve statistical significance. They suggest that any positive effects are likely to be at best modest overall (k = 1; n = 358; s.m.d. = 0.14; 95% CI 0.35 to 0.06).
Olanzapine
The one small RCT of olanzapine (Butterfield et al, 2001) as a first-line treatment for PTSD was not positive (k = 1; n = 11; s.m.d. = 0.04; 95% CI 1.19 to 1.26). However, an underpowered RCT of olanzapine in the augmentation of SSRIs (Stein et al, 2002) showed a trend in favour of olanzapine (k = 1; n = 19; s.m.d. = 0.92; 95% CI 1.88 to 0.04), suggesting that further work in this area is warranted.
Risperidone
Risperidone for PTSD has been investigated only as an adjunct to other medications (Hamner et al, 2003) and it did not appear to be efficacious (k = 1; n = 37; s.m.d. = 0.1; 95% CI 0.55 to 0.74).
Non-RCT trials
No other true RCTs were identified by the Guideline Development Group, although several other drugs have been used for PTSD. For example, some benzodiazepines, including clonazepam, alprazolam, carbamazepine, clonidine and prazosin, have been reported as being efficacious in open-label trials, case reports or case series. Further evaluation of these and other drugs will be required before it can be determined whether they are effective. However, the adage absence of evidence is not evidence of absence of effect holds true.
| Prescribing for PTSD |
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The NICE guidelines recommend paroxetine and mirtazapine as the drugs with most evidence for widespread use, with amitriptyline and phenelzine being reserved for initiation by secondary care professionals. There are limitations to all these drugs both in terms of limited evidence (see above) and their side-effect profiles. It seems likely that many prescribers will continue to feel more comfortable prescribing antidepressants they are more familiar with, despite the absence of an evidence base.
| What dose? |
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| How long should treatment continue? |
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| Adverse effects |
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Some individual studies have reported adverse effects. One RCT (Davidson et al, 2001a) found that, compared with placebo, sertraline significantly increased insomnia, diarrhoea and nausea, and decreased appetite. An RCT comparing paroxetine with placebo (Tucker et al, 2001) found that nausea, somnolence, dry mouth, asthenia and abnormal ejaculation had an incidence of at least 10% and twice that of placebo. In one RCT (Davidson et al, 2003) three people taking mirtazapine withdrew because of adverse effects, including sedation, panic attacks, increased anxiety and irritability. Three people taking placebo withdrew because of pain, or lack of efficacy; more people taking mirtazapine had increased appetite and weight gain. It is also important to consider the possibility of a discontinuation syndrome with the SSRIs, and paroxetine in particular, and to follow the well-publicised prescribing details (Duff, 2004).
| What if the patient fails to respond? |
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| Comorbidity |
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| The future |
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| Declaration of interest |
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| MCQs |
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MCQ answers
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| References |
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