what is the evidence for and against the roles of traumatic experiences in the development of auditory-verbal hallucinations in individuals with schizophrenia
FOR
aberrant memory
source monitoring
dissociation
failure of inhibition and unintended recall
intrusive memories out of context
sense of otherness
Read et al. (2005) (112) sugest ambiguity between inner and outer experiences may be a way of avoiding reliving the trauma.
hippocampal hyperactivation present supporting that AVHs are memory intrusions
increased frontotemporal activity involved in speech perception and medial temporal lobe which is involved in verbal memory
auditory hallucinations are auditory representations derived from unintentional activation of memories and other irrelevant current mental associations. a combination of deficits in intentional inhibition and contextual memory is critical for AHs
failure in intentional inhibition produces uncontrollable events which aren't recognised because the contextual cues that would usually facilitate recognition have been lost.
goes against traumatic experiences, because the model says any memory can be unintentionally recalled, not just traumatic ones, and the problem is with the contextual cues and inhibition.
can then make the point here that traumatic memories are intrusive.
intrusive memories don't account for the more complex auditory experiences
for example, neutral or benevolent voices. although they are less common in schizophrenia they still occur
(Peters et al., 2012) - benevolence was associated with engagement of the voices (this shows there are benevolent voices in Schizophrenia)
Laroi et al., (2018) predicts that 50% of schizophrenia patients have benevolent hallucinations and 80% of schizophrenia patients have malevolent hallucinations
AGAINST
EVIDENCE FOR THE PRESENCE OF TRAUMATIC EXPERIENCES
VH prevalence in non-clinical populations is between 1-16% in adults
dissociation is hypothesised to exert a twofold influence between voice hearing and trauma, via fragmentation of self components
VH experiences can be most appropriately understood as dissociated or disowned components of the self that result from trauma, loss or interpersonal stressors
argued that dissociative responses to serious adverse experiences could fragment ordinary memory processing
verbatim memory for what the voices said is poor, so they aren't remembered experiences (Sachs, 1967)
Read et al (2003) also in 112 found child abuse predicted AH in a mixed psychiatric sample
missattribution (source error) from internal to external would lead to a reduction in distress
Trauma exposure in childhood results in heightened sensitivity to stress and perceived threat- Bremner 2002, Nemeroff 2004, Read et al 2001
if there is more perceived threat in the environment this can exacerbate symptoms
the traumatic content of the AVH can be contributing and reinforcing the symptoms, leading to a feedback loop of trauma by reinforcing it
childhood trauma was positively associated with the dissociation scores and hallucination scores, and dissociation scores was a potential mediator between childhood trauma and hallucinations (Perona-Garcelan et al. 2012)
Varese, Barkus and Bentall (2012)
dissociation positively mediated the effect of childhood trauma on hallucination proneness (not AV specific). this was particularly robust for sexual abuse
found source monitoring was impaired in both currently hallucinating and remitted hallucinating patients.
No association between source monitoring performance and childhood trauma was found
source monitoring may play a role in AVH without the role of trauma
Read et al (2005)
found symptoms considered hallucinations are at least as strongly related to childhood abuse and neglect as many other mental health problems
methodology
the need to rely on self report for a lot of these studies is an issue- as they may be unaware of some connections between memories and hallucinations
reliability of self report measures
questions of the reliability of report is not based in evidence
sexual abuse specific factor
Read et al., (2003)
Dose response relationship
Morrison and Peterson (2003) predisposition to AH was significantly higher in those who reported multiple traumas. emotional and physical assault were related to a predisposition to auditory hallucinations. this is in a non-clinical population though.
an external trigger for the onset of voices was identified in more than 50% of the subjects in the schizophrenic group.(Honig et al., 1998)
"in most cases, the onset of auditory hallucinations was preceded by either a traumatic event or an event that activated the memory of an earlier trauma"
patients with psychosis were 2.72 times more likely to have been exposed to childhood adversity than controls (Varese et al., 2012)
Darves-Bornoz et al (1995) found "the problem of incorrect allegations of sexual assaults was no different for schizophrenics than the general population"
Bendall et al. (2007) crticisised the methodology of childhood trauma and psychosis studies. 40/46 studies didn't have satisfactory control groups and out of the 6 left, only three found statistically significant associations. They suggest problems with these studies involve a lack of statistical power, lack of attention to moderating or mediating variables, the way in which childhood trauma was measured, and the use of cross-sectional research designs. They also suggest some of these problems are unavoidable in childhood trauma research due to the methods required to assess these topics.
Shelving et al. (2006) when controlling for background variables, a history of childhood rape and molestations, but not neglect or physical abuse were significantly associated with auditory hallucinations.
multiple types of trauma were associated with increased in the likelihood of auditory hallucinations
Bentall et al. (2007)- three theories of trauma and hallucinations
first, source monitoring deficits precede trauma. those that experience trauma later end up with intrusive involuntary cognition, and those with source monitoring deficits misattribute these as hallucinations.
it may take time, as the person dealing with the trauma later becomes retraumatised (Honig et al. 1998)
second, trauma impedes source monitoring ability. hallucinations are associated with dissociation, which involves a failure of integration of information processing, so some normally conscious mental activities are performed without awareness, and source monitoring may be adversely affected as a consequence.
third, incorporates the assumption that psychotic experiences occur on a continuum in the general population. the experience of thoughts misattributed to an external source as a result of biased source monitoring is a common phenomenon, but trauma differentiates between patients and non-patients.
if this was the case, trauma should be much less closely associated with voices in non patient groups
"childhood trauma is conceptualised to cause more severe hallucinations throughout source monitoring errors, as, intrusive memories involving low cognitive effort make an individual vulnerable to hallucinations, particularly if they have compromised source monitoring"- Bailey et al (2018)
Bentall et al (2013) found that for those with FEP, those with CSA had more severe hallucinations than those without CSA. they also did an emotional troop test and found that post traumatic intrusions at clinical levels and showed selective attention to CSA related words. this does suggest that trauma affects the severity of hallucinations, but I have to be careful when specifying this to DEVELOPING AVH
However, Bentall et al. (2011) gave FEP and matched non clinical controls a source monitoring task and found no externalising bias for trauma words in those with childhood trauma. this suggests external source monitoring bias may not be central to hallucinations early in psychosis. it does not support the idea that intrusive memories of trauma are externally misattributed
therefore, trauma may not play a role in the development of AVH, but potentially the severity of later AVH.
can then link this to another theory that isn't related to externalising biases.
Dissociation maybe?
"weak contextual integration during he encoding of highly stressful traumatic memories may lead to involuntary triggering in those with biological vulnerability" Bailey et al 2018
this then links to dissociation and source monitoring
found childhood trauma was significantly correlated with hallucination severity, which included clinical samples. (Bailey et al. 2018)
Daalman et al. (2012) found both psychotic and non psychotic patients with AVH experienced more sexual and emotional abuse when compared with healthy controls. suggests that these abuse types make a person more vulnerable to experience AVHs.
suggests maybe trauma isn't the difference between clinical and non-clinical populations as the AVH non psychotic group had trauma but no diagnosis. maybe trauma affects AVH regardless of schizophrenia.
the link here is that one says trauma might not play a role in developing schizophrenia, just later severity, the other says trauma plays a role in AVH regardless of schizophrenia diagnosis.
high degrees of stress can reduce the reactivity of the hippocampus, leading to a hyperarousal state. trauma causes stress, stress alters connections between hippocampus and parahippocampal gyri which integrate and transfer information into the hippocampus. so information from hippocampus may be incorrectly activated and generate a hallucinatory response
activity in the left parahippocampal gyrus and the hippocampus has been related to AVHs (Jardri et al 2011)
the role of memory in AVHs might not necessarily be traumatic ones
Whitfield et al. (2005) found that those with a history of hallucinations were more likely to have been abused during childhood. the population of the study was 17337
although the population was large, the measure of hallucination is only one question(methodology issue)
Other theories of schizophrenia
don't necessarily challenge the role of traumatic experience
Dopamine Hypothesis
Spauwen et al (2006) speculated that extended exposure to trauma may increase risk for dopamine hyperactivity in the mesocorticolimbic system and prolonged exposure to aversive environments can lead to sensitisation of the system.
Da Bellis et al. (1994) also found elevated dopamine metabolism in girls who have been sexually abused.
this research is outdated and more needs to be done to establish whether this is accurate to schizophrenia.
Read et al (2005)- suggested that early prolonged and severe trauma can permanently affect the HPA axis. dopamine is involved in post stress maintenance in the HPA axis (Belda and Armario, 2009)
Heim et al (2000) found HPA dysregulation in women who were abused in childhood
more research needed to see if this applies to schizophrenia
Sheffield et al (2013)- psychotic patients reported more childhood abuse than controls. psychotic patients with a history of AH reported significantly more sexual, emotional and physical abuse than those without a history of AH. emotional and physical in the absence of sexual abuse didn't lead to a higher rate of AH.
hallucinations were significantly more common for the abued group than the non-abused group. adult sexual assault was related to hallucinations in general, and child abuse was a significant predictor of auditory hallucination, even in the absence of adult abuse
Bentall et al (2012) reported that those who reported being raped prior to age 16 were six times more likely to have experienced AVHs in the 12 months preceding assessment. physical abuse prediced AVHs, bullying was non-significant.
dose response relationship was found between number of childhood traumas and risk of AVH.
Shelving et al (2011) found that rape, sexual assault and physical assault were significantly related to AH. those raped in childhood were 3.5 times more likely to experience AH than those not. rape and physical assault predicted auditory hallucinations.
also found a dose response relationship
this is contrary to Shelvin et al (2006), who found physical assault wasnt associated with AH
Hardy (2017)
3 vulnerabilities
two types of intrusion
attempts to survive trauma become habitual ways of regulating emotions, manifesting in cognitive and behavioural responses
event memories are impacted by emotion experienced during trauma
semantic memory- appraisals of the self and others, are shaped by event memories
anomalous experience rising from emotion regulation or generation of novel images derived from trauma memory
this can be an integrative account at the end I think
hypervigilance to danger following childhood trauma could result in reduced threshold for threat detection
environmental noise is perceived as threat, leading to intrusions of anomolous experience
dissociative detachment- dissociation in an attempt to manage threat could give rise to intrusive experiences because it has a detrimental impact on sensory perceptual processes, so it allows consciousness to be intruded upon
autobiographical memory- the working self draws on personal memory representations to generate novel imagery
these intrusions that are driven by emotion regulation and autobiographical memory might explain experiences that appear unrelated to trauma history.
trauma memory intrusions reflecting the retrieval of representations
there is a continuum of memory intrusions, and fragmented memory, where the memory is present without the contextual cues to put these in place will lead to a misattribution of the source. those memories that are fragmented are unlikely to be perceived as arising from memory events.
Hardy et al (2005) found 12.5% of hallucinations were a direct replication of trauma and 45% had an emotional link
McCarthy-Jones et al (2014) interviewed 199 voice hearers, 12% reported identical replays of conversations, 31% reported a similar relationship between memory and what they heard. the previous conversations being assessed weren't necessarily traumatic
they could be underreporting their conversations, as traumatic memories that were linked to their AVHs might not have been linked to their conscious recollection of the memory
as hardys model says, without the contextual information they may not attribute their experience to their memory. similarly, they may have novel experiences that are based in traumatic experience, and not be aware.
Goodman, Thompson and Weinfurt (1999) found those with a serious mental illness showed good consistency for reports of abuse occurance
traumatic memories are often formed into information that is not identical to the experienced event (Conway & Pleydell-Pearce, 2000)
this is likely to exacerbate the potential for confusion when experiencing hallucinations and attempts to locate the origin of these phenomena
Waters et al. (2006) is this view
this link to prior trauma through the content of them suggests that trauma must have had a role in the development of them
this is still not 100%, so there has to be other factors acting on it, but it could also be a result of not linking it together or realising they were connected. this is a problem with self report measures. put the methodology point here.
these show the link between source monitoring and schizophrenia, not trauma.
Humpston et al (2017) found that the positive dimension of schizotypy was positively correlated with internal and reality monitoring errors in an action based task.
to disagree with this again: Waters et al (2012) found reduced self recognition performance in schizophrenia patients, which was more pronounced for patients with AH
several cross sectional studies have demonstrated that dissociation mediates the relationship between trauma and AVHs
Perona-Garcalen et al (2012)
and Varese et al 2011 found reports of dissociation reliably preceded the onset of AVH. these obviously require further research but it is an interesting point.
the association between hallucinations and sexual abuse is clear, but the association between sexual abuse and AVH is not.
Although McCarthy-Jones (2011) found that those with CSA experiences were more likely to report AVHs than those without, and vice versa, they concluded a causal relationship cannot be established due to the failure to control for potential confounding variables.
definitions also need to be very clear about what counts as a traumatic experience, and what comes under each catergory
the genetic heritability of schizophrenia suggests its a genetic disorder, not fully traumatic, although there is room for it to be triggered by trauma