Delusions are a common concern in forensic psychiatry, as one part of the triad of psychosis which includes delusions, hallucinations and thought disorder.
The classical definition of a delusion is “a fixed false belief which persists despite evidence to the contrary and which is not culturally bound.”
The nature of an individual’s delusions varies with the patient and is often related to the cultural background. The broad content of delusions ranges widely.
Technological delusions are common and often involve the belief that a microchip has been implanted in the brain allowing others control of the patient’s actions. This is clearly a relatively modern delusion which has arisen since the development of the microchip.
Religious delusions are still common and often involve the belief that one has been given divine powers or that one has a special connection with the divine. Occasionally these delusions are more specific, with the belief that one is Jesus or another significant religious figure.
In the nineteenth century, these grandiose delusions often involved Napoleon Bonaparte, a major figure of the time.
Delusions of the occult are also relatively common, with beliefs about black magic, curses, spirits, demons and the devil being observed regularly in patients from a range of backgrounds ranging from people with a cultural and religious background centred on modern Western European ideas to patients who look to the Caribbean or Africa for their cultural influences and also seen across patients who follow Islam.
There are also more mundane delusions, such as the belief that an individual or individuals are spreading rumours about a person or, even more non-specific, a general sense that a group of people bear ill will or some sort of non-specific malicious intent.
Delusions range in complexity from the very simple to the very elaborate and this often correlates with the level of intellectual functioning of the patient. Patients with a more complex internal world will often have well-developed systematised delusions which they often elaborate in writing and which can be very complex and wide-ranging. Patients with a lower level of intellectual functioning and a relatively simple internal world will often talk about half formed ideas and suspicions centred on immediate neighbours, the local fish and chip shop, the local council and so on which can be vague, non-specific and half-conceived
It is easy to see that these delusions often bear no relation to reality at all and, indeed, part of the definition of a delusion is that it is a false belief.
People who are less familiar with these aspects of the human psyche are often startled by the fact that there may be a some truth to the delusion.
Delusions often relate to subjects about which the person already has strong beliefs. Religious delusions generally occur in people to whom religion already has significance, whether negative or positive. People with delusions about their neighbours often have pre-existing strong feelings about their neighbours. A patient who believes that their neighbours are poisoning them in order to gain control of their affairs probably has negative feelings about the neighbours before any mental illness or symptoms of psychosis manifest. There may already have been some sort of neighbourly dispute before the delusional ideas arise.
A delusional patient who believes that a relative is persecuting them by means of black magic probably already had a strained relationship with that member of their family before the mental health issues arose and the delusions came along.
When exploring or coming to understand the patient’s thinking, people new to this area, including medical students and lay tribunal members, are often struck by the truth at the heart of what can be a wide-ranging and expansive delusional system.
Even in patients with a long (over 10 years) history of the classic symptoms of schizophrenia including third person auditory hallucinations, disorders of thought possession and passivity phenomena, novices in this area are struck by the realisation that the neighbours who have been supposedly pumping poison gas through the walls, using a super chip to control the patient’s behaviours or controlling their actions through voodoo were at one stage involved in a real dispute of some sort with the patient. This realisation is sometimes seen as casting doubt over the diagnosis or changing the situation fundamentally. The layperson assumes that because there is a tiny morsel of real grievance, the entire wider clinical picture is brought into question.
It is clearly the job of the forensic psychiatrists to provide context and the fact that there was an argument between neighbours 15 years ago or the fact that there is still genuine tension between a son and his mother-in-law does not adequately explain a 15 year history of hallucinations, delusions, thought disorder, personality disintegration and poly-substance misuse which is absolutely characteristic of schizophrenia. In fact, the opposite is true: in someone with specific delusions about an individual or group of people we would actively expect that there might be some pre-existing animosity or difficulty between the patient and the other.
This is the truth at heart of the delusion.