The great majority of terrorists aren't found to have any form of mental illness. However, the situation is less clear with so-called 'lone actors', 'self-starters' or pairs who aren't part of any mainstream group.
Perpetrators of the latest series of attacks in the headlines in various parts of the West, appear over-represented by relatively recent religious converts. Other terrorists are reported to have become newly dramatically more fundamentalist in their views. Profound contemporary changes in personality are corroborated by reports from school friends, past acquaintances and relatives of perpetrators, who describe not recognising the current character of the alleged criminals.
Another recurring feature is that some of those currently accused of terrorist crimes, have in fact been on the radar of intelligence services previously. Questions have been raised as to why the potential dangers that individuals posed, had not been recognised.
There is, however, a psychiatric explanation that might help explain the over-representation of recent converts - and also why assessments of risk may prove especially unreliable in some of these cases.
This elucidation would fit the facts, is debated amongst doctors, but has not been discussed by politicians, public and press.
Dr Dinesh Bhugra, a former president of the Royal College of Psychiatrists, alludes to aspects of this phenomenon in a paper entitled 'Self-concept: Psychosis and attraction of new religious movements'. He points to data from studies showing that patients with first onset psychosis are likely to change their religion. Another intriguing finding from his research, is there appears to be links between coming from an ethnic minority, and recent religious conversion being more associated with a developing psychotic mental illness.
In one of Dinesh Bhugra's studies in London, quoted in the academic journal 'Mental Health, Religion & Culture', 100 cases of first onset psychosis were recruited. Of the white patients - none showed more religious activity linked to becoming psychotic, but 23% of the Asian, 9% of the Trinidadian and 13% of the African-Caribbean patients did.
Why this link between increased interest in religion, elevated religious activity or conversion should be particularly apparent in ethnic minorities remains puzzling, but one possible answer comes from Bhugra's paper, where he points out that research has also found a link between being a religious minority and psychological strain.
Bhugra quotes studies amongst New York school children; Catholics raised in non-Catholic neighbourhoods were more likely than Catholics raised in a predominantly Catholic neighbourhoods, to suffer low self-esteem, feel depressed or report psychosomatic symptoms. Similarly adherents of other religions raised in neighbourhoods where they were the minority, were more likely to manifest signs of emotional disturbance.
There was no clear difference in emotional distress between those raised in neighbourhoods with exclusive or half co-religionists, suggesting that whether everyone in the neighbourhood is of one's own group is less important, once there are enough to offer social support, a sense of belonging and acceptance.
Bhugra points out that both religion and psychiatry are interested in profound changes-of-heart. If someone is becoming aroused by disturbing mental states produced by the onset of serious mental illness, they may be drawn to the extreme beliefs in fundamentalist religions. Personal crisis may lead to conversion to a new or more intense religious faith for all sorts of psychological reasons, including heightened vulnerability to persuasion.
Profound personal change in personality is associated with religious conversion, and such a transformation can be indicative in some cases of mental illness, particularly a psychotic type. This suggests perils for the security services in conducting a one-off risk assessment and moving on, assuming that threat will remain low. Sudden and profound transformation of the kind associated with mental illness, or religious conversion, means that a more dynamic assessment approach to developing risk is essential, where such factors may be present.
Psychiatrists are used to unpredictable change requiring careful on-going monitoring.
Within medicine certain neurological and psychiatric conditions are well known to be linked to sudden religious conversion. For example, in a paper entitled 'Sudden religious conversions in temporal lobe epilepsy' by eminent psychiatrists Dewhurst and Beard, reprinted in the academic journal 'Epilepsy & Behavior', originally published in the 'British Journal of Psychiatry', mystical delusional experiences are reported as remarkably common in psychotic illnesses associated with some forms of epilepsy.
Dewhurst and Beard go on to catalogue famous religious conversions in history, pointing out how illness and psychosis could provide alternative explanations for many epoch-changing mystical experiences. For example, they discuss the possibility of some form of epileptic illness, or even migraine, as associated with the sudden conversion of St. Paul.
Before, Paul hunted and persecuted Christians, but he was completely transformed on the road to Damascus, where he suddenly fell while experiencing visual and auditory hallucinations, plus transient blindness. As a direct result he converted to Christianity. Various doctors have debated alternative medical explanations for possibly the most famous religious conversion in history. Dr John Bullock, in 'Survey of Ophthalmology' even published a paper entitled 'Was Saint Paul Struck Blind and Converted by Lightning?'
If some sudden religious conversions, raise in doctor's minds the possibility of various kinds of medical, neurological or psychiatric illnesses - why shouldn't they for the intelligence services?
We are not arguing that all religious conversion is linked to psychosis or neurological illness, nor that all religious conversions are dangerous. We are suggesting that profound personality change secondary to psychotic illness could be emerging as a possible factor in some domestic terrorist incidents, possibly particularly where recent conversion to extremist religions appears to be a factor.
The psychology of religious conversion might need to be more closely considered by those engaged in the prevention of terrorism. And the potential danger that religious conversions may lead to, needs to be more broadly understood by psychiatrists who may be caring for those that undergo such experiences.
Those who have for lengthy periods flirted with extreme positions and actions may establish a reputation which alerts the authorities. Their risk to the community could end up being practically lower, because they are going to be most closely monitored by security agencies.
Greater risk may be attached to those who could be seen as a form of medical 'sleeper.' A sleeper agent being an operative acting undercover, only becoming a potential and dangerous 'asset' once activated.
Could in some cases psychosis trigger religious conversion, which in turn sets in motion previously unsuspected terrorist risk?