Overarching Sentencing Guideline

Annex Four: Main classes of mental disorders and presenting features

This information is only intended as general assistance to sentencers in understanding common impairments and mental disorders and is not intended to cover every situation.

Mental disorder is a catch-all term for illnesses and developmental disorders. Mental disorder is a collection of symptoms (the person’s experiences) and signs (features that may be observed by an outside observer). For categorisation as a disorder, these problems should be associated with distress and/or interference with personal functions.

Broadly the concept of illness is used for disorders which start after a sustained period – often a lifetime – of health or average/normal psychological function e.g. schizophrenia, depression.

Developmental disorders are conditions which may be apparent at birth, but always have early enough onset that the individual never quite fitted within the average behavioural range. Behaviour has three main components – thinking (cognitions), feeling (emotions, affect) and actions. Autism, generalised or specific intellectual (learning) disabilities, and personality disorders are examples.

Other disorders which may be relevant in court lie at the interface between psychiatry and neurology. Epilepsy in its various forms is an example, Acquired Brain Injury (ABI) is another example. ABI is an injury caused to the brain since birth, most often as a result of trauma, tumour, stroke, illness or infection.

Brief descriptions of some of the more common disorders likely to be relevant in court:

Psychotic illnesses 

These affect cognitions, emotional capacities and actions.

There are two main groups – those which are associated with more generalised illness or bodily problems, often called ‘delirium’, and those which are not – often referred to as ‘primary psychosis’, which include schizophrenia and bipolar disorders.

Delirium is likely to present with some impairment in consciousness. It may occur as an acute phase of a dementing process, but also with serious infections or generalised problems with bodily functions, such as hormonal disturbances. Delirium may also occur in the context of drug (including alcohol) taking or withdrawal from such substances.

People may misinterpret sensory input in any of its main forms (sight, hearing, smell, taste, touch), thus having ‘illusions’; their sensory experiences may be so disturbed that they see or hear or smell or taste or feel things which are not there at all to the external observer (hallucinations). Their thinking may be disturbed in its own right, or following from these perceptual problems, such that they have pathological beliefs (delusions).

Delirium is likely to resolve as the underlying condition is treated.

Schizophrenia and bipolar disorders are disorders in which consciousness is unimpaired, but sensory (illusions, hallucinations) and cognitive (delusions, formal thought disorder) disturbances occur.

In schizophrenia, serious disturbances of emotion also occur in which the person either cannot experience or express emotions accurately, or both, and may be unaware of the difficulty. Terms like ‘incongruous affect’, when the emotional experience or expression is the opposite from what a healthy observer might expect for the situation, or ‘flattened affect’, when the person seems to have little or no emotion at all, are quite common. Tests for empathy may show that this is reduced.

People may also present with ‘formal thought disorder’ – when the form of thought, and thus speech is hard to follow and may include nonsensical, made-up words.  Hallucinations most commonly take the form of ‘third person hallucinations’ when the person hears others talking about them, but when no-one is doing so.

Delusions are beliefs which, in full form, are wholly impervious to reason, generally, but not always based on a false premise.  Persecutory/paranoid delusions are probably the most common.  Passivity delusions – when the individual ‘knows’ that his/her thoughts, feelings or actions are controlled by another person or an external system – may be particularly associated with violence.  If hypochondriacal delusions occur, they tend to be bizarre and may be dangerous – for example a belief in a machine causing all the problems implanted in his/her eye.  Many aspects of schizophrenia are treatable, but ‘cure’ is unlikely and deterioration over years quite common. Nevertheless, people with the condition can attain a good quality of life and safety if a full range of relevant treatments can be sustained.

Delusional disorder is sometimes diagnosed when the only abnormality appears to be the presence of a single delusion and can be easily missed.  Apart from the impact of the delusion or its ramifications, functioning is not markedly impaired, and behaviour is not obviously bizarre or odd.

Bipolar illness – also referred to by the older, now less used term ‘manic depression’ – is characterised by repeated episodes of depression (low mood and low activity levels) and (hypo)mania (high mood and high activity levels).  Psychotic symptoms are not invariably present at either extreme, but depressive psychotic symptoms include hypochondriacal delusions of a kind that the person believes his/her body is rotting away, or delusions of catastrophe; suicidal ideas are common and the rare situation of family killings with suicide of the perpetrator may occur in such states.  In a manic phase, the individual may have grandiose or omnipotent delusions, accompanied by reckless and/or disinhibited acts.

Unipolar affective illnesses – people may have recurrent depressions or recurrent manic episodes, but not both.

Schizoaffective illness looks like a hybrid of schizophrenia and bipolar disorder; it may not be a distinct disorder.

Non-psychotic illnesses

These include depression (seriously low mood and perhaps suicide related behaviours, but without delusions) and anxiety disorders. The latter include a range of conditions; the more common include phobic disorders (people recognise that their fear is not well founded in fact, but experience fear anyway which may interfere with their everyday life), obsessive compulsive disorders (again, the fear recognised for what it is, but still thoughts and fears intrude and maybe rituals must be performed), panic attacks and post-traumatic stress disorders [PTSD].

PTSD can only be diagnosed if it follows a seriously traumatic event which happened directly to the person, which the person witnessed as it happened to others and/or had to deal with the aftermath (emergency service workers may be as vulnerable as the general population), or which the person learned about soon afterwards but it affected someone very close to him/her. Generally, the scale of the event is taken to be life-threatening or life-changing and/or that the person affected unquestionably thought it so.  Guidance is that the condition must emerge within six months of this – it may not be immediately apparent.  It is important to have evidence that the condition did follow the event.  Most people will get some of the symptoms or signs in such circumstances; guidance is that these may be collectively regarded as a disorder if they persist to a degree that they are disruptive to the individual’s usual lifestyle for over a month.  There are people who have experienced multiple traumas and the presenting features may therefore represent a worsening/exacerbation of PTSD which started after a previous event rather than a completely new presentation.

As well as mental and physiological symptoms and signs (like racing heartbeat, tight chest, uncomfortable sensations in the gut), and of anxiety, and often some depressive features, typical features are:

  • extremely distressing intrusions of memories or experiences of the event which disrupt waking life (flashback memories) and/or sleep (nightmares), dissociative reactions (if the surroundings are perceived as unreal this is called ‘derealisation’. If the person him-or herself feels detached, outside him/herself and/or more as an observer of self than a real person this is called ‘depersonalisation’), when the individual is not very aware of his/her real surroundings but living again in the trauma; sometimes specific real experiences may trigger this (for example if an assailant had been wearing a particular perfume/aftershave chance contact with a perfectly harmless person who happens to use the same may trigger a flashback and reaction more appropriate to the traumatic experience than the reality);
  • persistent, active avoidance of any reminders of the trauma – including unwillingness to talk about it or inability to read documents relating to it;
  • persistent negative feelings about self and others – many have no concept of a future;
  • alterations in arousal – so, irritability, reckless behaviour, being over-watchful, problems with concentrating, exaggerated ‘startle responses’ to actually non-threatening events, various difficulties with sleep.
Developmental disorders

Intellectual disability [ID] (learning disability) – names for these conditions keep changing over time in a constant effort to reduce stigma. Problems may be generalised (probably most relevant in court) or specific – for example relating to a particular language function. As the labels suggest, the core problem is cognitive – those affected may have a lower than average ability to learn at all and to acquire language. Inevitably, this is an over-simplification as there are often problems with emotions and actions too, and it is hard to distinguish the extent to which these are part of the primary condition and the extent to which they follow from difficulties in learning. A tested ‘intelligence quotient’ (IQ) is often used to indicate severity – mild, moderate, severe. Average intelligence is taken as 80-120. A person with severe generalised intellectual disability will have a tested IQ under 35, and cannot live independently. In varying degrees those with moderate (IQ 35-49), mild (IQ 50-69) or borderline ID (IQ 70-80) can live independently, but are particularly vulnerable if they enter the criminal justice system.

Autism and autistic spectrum disorder (the latter sometimes referred to as Asperger’s syndrome, but this term is falling out of use) are pervasive developmental disorders in which intelligence may or may not be impaired, but emotional and relationship capacities, often with aspects of speech development, are. In recognition that these conditions encompass many shades of disorder and disability, and sometimes extraordinary but atypical abilities, there is a growing tendency to use the term ‘autistic spectrum disorder’ with indications of the specific behaviours affected and the severity. As understanding of some of the more specific underlying mechanisms in their development grows, identification of such disorders is increasingly being made for the first time in adulthood. The American DSM-5 no longer uses the term autism at all. It is still used in the UK, generally to indicate the most pervasive and extreme incapacity to understand or empathise with others, to show any emotional reciprocity and to develop or maintain relationships. Generally, the individual seeks ‘sameness’ and so is inflexible in routines or repeated, simple actions and may become very aggressive if interrupted.

‘Autism’/autistic behaviours were once seen as one of the core sets of features of schizophrenia, and may still be referred to in this context. The underlying neurological/brain difficulties may well be similar in some respects, but these are distinct conditions. Most people with autism/autistic spectrum disorders do not become psychotic.

Attention deficit hyperactivity disorder [ADHD] is similarly apparent from a very early age, although may not be completely recognised until the individual starts school. It is not uncommonly associated with other developmental disorders, but also occurs alone, when it is characterised by profound difficulties in concentrating in ordinary social situations or on tasks (many can focus on computer based activities) and very high levels of physical activity.  Children are seen as ‘disruptive’ and can easily be made worse under conventional behavioural control efforts. As with all developmental disorders, it may persist into adult life.


Substance misuse disorders

Substance misuse disorders arise when the individual no longer has significant personal control over intake and/or he or she has signs and symptoms of secondary disease. Substances of abuse affect the nervous system, often altering its activity so that the experience of the consumer is that when he or she does not have the substance they have very unpleasant symptoms or signs ranging from intense anxiety through to psychotic symptoms (withdrawal symptoms/signs), and so the consumer has to keep taking the substance in order to feel almost normal. Secondary disease may affect any part of the body, although most commonly those areas that process the substances – like the gut or the liver – and the brain.

Conduct disorders, if unresolved, are the childhood precursors of personality disorders. Emphasis is on repeated patterns of extreme dissocial, aggressive or defiant behaviours, persistent through childhood, which cannot be completely explained by one of the other developmental disorders.

Personality disorders. The personality is not considered to be fully formed until adulthood, so, by definition these are conditions which can affect only adults. Although adulthood is often taken as 18 years old, there isn’t a set time threshold when the brain and physiology is one day that of a child and the next of an adult. For a diagnosis of personality disorder, there must be evidence of continuity with problems such as conduct disorder throughout childhood and adolescence. Similar conditions may arise in adulthood after, say, brain injury or disease, but this would be personality change.

Specific personality disorder labels are generally descriptive, following from their most prominent characteristics. Treatment needs mean that is probably most helpful to think of the personality disorder clusters rather than specific disorders – thus:

Cluster A – the paranoid, eccentric, schizoid

Cluster B – the emotionally unstable, histrionic, narcissistic, antisocial

Cluster C – the anxious, avoidant, obsessional (anankastic), dependent

‘Psychopathic disorder’ is not a recognised diagnosis; its use should be avoided as pejorative and unscientific.  ‘Psychopathy’ is similarly not a diagnosis, but rather a term that has been introduced to indicate whether a person had crossed a threshold on one of a number of possible psychopathy scales. Generally, these scales measure two things – the extent to which antisocial behaviours are widespread and have been repeated through the life course, and the extent to which the individual has capacity for empathy.

Both these elements have, correctly, been used as indicators of risks or repetition of unwanted behaviours. It is obvious that established behaviour patterns are likely to continue unless deliberately disrupted; on the other hand, it is always easier to tell if progress has been made when a previously repeated behaviour ceases over a substantial period of time under a range of circumstances.

If empathy is severely impaired – for example the capacity to recognise distress in others and make appropriate use of that information – this may severely impair capacity to desist from harming others.

Risk of harm to self is very high among people with personality disorder.


The Dementias

Dementia follows from brain damage. Each aspect of behaviour may be affected. The most obvious is the cluster of cognitive problems, with forgetfulness, difficulties in following a train of thought and making judgements prominent. There are commonly also directly related emotional problems, as the brain can no longer control emotions, and also secondary emotional problems when the person retains insight and is aware of progressively losing his or her mental abilities. Capacity for control of actions may also be impaired, resulting in what is often referred to as ‘disinhibited behaviour’.

Evidence for dementia will come in several forms – the clinical examination, which should include asking the affected person about his/her experiences and for a history of the development of the condition; for obvious reasons it is more than usually important to get a history from relatives and friends too. People with dementia may retain the capacity to give a long and fascinating account of their problems which has little basis in reality (referred to as confabulation).

Simple tests of memory and other cognitive functions may be enough for basic diagnosis and to help the court, but it is generally best to map cognitive functions with detailed psychological testing, and there may be some very specific deficits which are relevant in court – for example difficulties in recognising people or experience of perceptual distortions. Brain imaging techniques may have particular value in verifying the nature and extent of the brain damage underpinning the problems.

The dementias are progressive. People may be helped to manage their difficulties, sometimes the progress may be slowed, and sometimes worsening of some aspects of the condition may render other aspects less problematic or risky, but these are not conditions from which people recover. 

The most common dementias are a function of unhealthy aging.  There has been an increase in offending among older people, so these are conditions increasingly likely to be seen in the courts. A few of the dementias, usually those with early onset, have a clear genetic cause; there is evidence that there is a genetic contribution to most.

Alzheimer’s disease/dementia is among the commonest given a name. The pattern of destruction of brain tissue is more-or-less specific to this dementia, and there is a genetic component to it. Where the genetic component is strong, onset may be at a younger age (50, occasionally younger) but more typically onset is around 65-70. The characteristics are more-or-less as described above. Variations in presentation often indicate which parts of the brain are most affected at any particular time, but this is a generalised condition.

One of the more difficult dementias to recognise in relation to offending is fronto-temporal dementia (referring to the lobes of the brain most affected). Compared with other dementias, memory is spared for longer, but behavioural problems may be prominent. It is also less common than Alzheimer’s or dementia of old age, and more often missed. It should be considered if a well socialised person becomes aggressive or antisocial for the first time in later adulthood (onset generally 45-65). 

Dementias may also, however, follow from brain damage from external causes, for example a serious head injury, in relation to other disorders affecting the whole body, like diabetes, or from having taken noxious substances – especially excessive alcohol, but a range of other drugs too.


Acquired brain injury (ABI)

ABI is an injury to the brain which has occurred since birth. Causes include: tumour, stroke, haemorrhage, encephalitis, carbon monoxide poisoning, hypoxic injury or trauma.  Principal causes of trauma resulting in ABI are falls, road traffic collisions, workplace injuries, violent assault and sporting injuries.  Even after a minor head injury, brain function can be impaired temporarily (concussion).  Effects include headaches, dizziness, fatigue, depression, irritability and memory problems, lasting for weeks, months or even years.

Survivors of more severe brain injury are likely to have long term problems affecting their personality, relationships and ability to live independently. Issues can be compounded as the effects of ABI are often hidden and may fluctuate. The cognitive, psychological, emotional and behavioural effects of brain injury can be difficult to detect by those without specialist training.


Multi-morbidity and comorbidity (dual diagnosis)  

These terms are often used interchangeably to mean that the individual has more than one disorder although, strictly, comorbidity means that the conditions arose simultaneously. This is a very common situation among people who have a disorder of mental health. It is generally very hard to disentangle which disorder came first or whether they arose simultaneously. Psychiatrists and other clinicians still sometimes use the term ‘dual diagnosis’. The term ‘dual diagnosis’ was invented to describe people who had a psychosis and a substance misuse disorder, but sometimes people use it for other pairs of disorders (e.g. psychosis and personality disorder) and, in practice, it is quite usual for people who come to court and have more than one disorder to have several – so a psychotic illness and more than one substance misuse disorder and a personality disorder and sometimes also a learning disability.      

Where focus is on psychosis and substance misuse disorder, it is not clear that it matters clinically, except insofar as the idea that a psychotic condition is ‘drug induced’ may, in the context of scarce service resources, be used to deny services. In addition to having several mental disorders – for example schizophrenia, personality disorder, cannabis use disorder and reactive depression – an individual is likely to be multiply disadvantaged socially – for example homeless or disconnected from family – and some clinicians will include these social disadvantages in the sum of comorbidities. They are certainly relevant to outcomes.


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17. Annex Four: Main Classes of Mental Disorders and Presenting Features
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