In 2026, the latest version of the World Health Organisation diagnostic classification system, the International Classification of Diseases 11^th revision (ICD11)¹, will become mandatory in the NHS. It seems timely to revisit the venerable psychiatric construct of schizophrenia and look at changes in our understanding of classification, psychopathology, and to revisit the various reasons why people with schizophrenia might encounter the criminal and civil justice systems and what considerations might need to be in place at those touchpoints. 

The Classification of Schizophrenia and it's Development

For those who are interested in psychiatric classifications, read on. Those less so can move to the next section. 

Schizophrenia - ‘split mind’ - was first described by Swiss psychiatrist Bleuler in the early 20^th century, although there are earlier descriptions. Whether it is a ‘modern’ ailment or whether it has always been part of the ills that beset humanity isn’t clear. It is also likely that it isn’t a single illness, but rather a group with substantially overlapping symptoms, courses and aetiologies. Bleuler’s theoretical model for the illness - which is not the same as our current construct – is that there was a separation of mental functions and what could be observed was a loss of psychological integration and coherence.  Bleuler’s work built on earlier models of Kraepelin, Morel, Clouston and Pick. A common feature of those descriptions was the use of the term ‘dementia’ either in labelling or describing the course of the illness and although ‘dementia’ then is not what we call dementia now, we will return to the importance of that element of the disorder in due course.  

When humans are confronted with something that is not easily understandable, they tend to resort to elaborate descriptions and systems of classification. A major development - I do not say ‘step forward’ - in classification took place in the 1950s with the work of Kurt Schneider who attempted to identify what he thought were core symptoms – those he described as of ‘first rank’ diagnostic importance. These are: disorders of the possession of thought (beliefs that thoughts are being broadcast from, put into or taken out of your head, for instance), passivity phenomena (beliefs that you are being controlled directly by some external agency), delusional perception (where something happens in the outside world  - traffic lights changing, for instance - and a bizarre or fantastic belief arises as a result) or particular types of hallucination -  hearing your thoughts being spoken aloud,  3^rd person auditory hallucinations (hearing a voice or voices commenting on your thoughts or actions, discussing you between themselves or coming from parts of your body) or somatic hallucinations (hallucinations occurring in your body – for instance experiencing internal organs moving around).  

Although Schneider observed that these first-rank symptoms were not always necessary or sufficient for a diagnosis of schizophrenia, his ideas gave an opportunity for the diagnosis of schizophrenia to become easily ‘operationalised’ and this approach first appeared in the 3^rd revision of the American classification system, the Diagnostic and Statistical Manual (DSMIII) in 1980².  First-rank symptoms reached almost pathognomic status in in the 10th revision of the Internal Classification of Diseases (ICD10)³. Alongside the reification of first-rank symptoms, the ICD10 describes several subtypes of schizophrenia – paranoid, hebephrenic, catatonic and undifferentiated. Laudable though efforts in DSM 111 and ICD10 to improve diagnostic reliability and consistency were, more recent work suggests that the presence or absence of these symptoms – which form in large part the ‘positive’ symptoms of schizophrenia, in that they are ‘additions’ to usual mental experience – are not exclusive to schizophrenia, are descriptive rather than explanatory, and do not determine prognosis. In addition, there is considerable overlap between the subtypes of schizophrenia and a person with schizophrenia may move from one type to another over the course of their illness.

Consequently, the ICD11 has moved to a simpler stance where a broader range of symptoms are given more equal status; subtypes of schizophrenia have been abandoned and the emphasis on first-rank symptoms has been diminished. In addition, the disorder can be coded as mild, moderate or severe.  A comprehensive review is provided by Valle⁴.  

Although the overall diagnostic rubric in ICD11 is similar to ICD10, symptoms are divided explicitly into 6 domains – positive, negative, depressed, manic, psychomotor and cognitive and it is possible to rate the severity of each domain in a particular case. This gives an opportunity to describe much more precisely the presenting features. In my view, the inclusion of cognitive symptoms as a domain in schizophrenia is a crucial advantage for the ICD11 over the DSM 5 and I shall explain why.  

Cognitive Symptoms in Schizophrenia

Cognition refers to the ability to receive, understand, process, store, recall, combine and use information to devise a model of understanding of the world and function effectively within it. Cognitive symptoms in schizophrenia refer to impairments in these functions. There is an overlap between these and other symptoms, but our nosological understanding is not well developed. DSM 5 takes the position that negative symptoms - a ‘minus’ from a normal state – include the manifestations of cognitive impairment and thus do not need separate descriptions. Negative symptoms include a loss of drive, a loss of emotional responsiveness, decreased enjoyment, reduced speech, poorer self-care and social withdrawal.  However, like the positive symptoms, they are not specific to schizophrenia and are not explanatory of this disorder but descriptive only. Some of these are, prima facie, reasonably linked to poorer cognitive function, some less so.  Harvey et al⁵  - and this is the approach in ICD11 – hold that while there is overlap, cognitive symptoms are a different domain from negative symptoms. 

Cognitive impairments in schizophrenia are common - and under-recognised. It is unusual for professionals in clinical practice to pay much attention even though cognitive symptoms are strongly predictive of outcome in terms of social functioning.  A cynical reader might observe that this is because none of the drugs marketed for the treatment of schizophrenia have much effect on this symptom domain. Bowie and Harvey⁶  review the academic literature, and report that cognitive impairments are usually at least moderate and often severe, predate the symptoms of frank psychosis and are unfortunately stable. Their review in the early 2000s struck a note of optimism about various possible interventions for cognitive impairments; sadly, this has proven over optimistic, and little has changed since.  Patients with schizophrenia as a group have a lower IQ than the general population and this can be detected before the onset of illness. Further decline in IQ appears to take place after the illness manifests.   Even if full scale IQ is normal, people with schizophrenia are likely to demonstrate abnormalities in specific neuropsychological tests not conducted in usual assessment batteries.  Particular areas of impairment in schizophrenia are capacity to pay attention, verbal working memory, verbal fluency, and executive function. This last, underpinning the ability to develop new responses to new demands, is a particular problem in the workplace. 

Schizophrenia and The Law 

There is nothing specific about the difficulties that people with schizophrenia might have that bring them in contact with the law compared to people with other forms of mental disorder. However, bearing in mind the likely presence of cognitive impairments of at least moderate degree as well as other symptoms, anyone dealing with people with schizophrenia should be aware of the need to make potential adjustments to usual process. It is not inevitable that these will be needed, but some consideration should always be given.  Reasonable adjustments might include repeating information, using simple language, checking understanding more frequently and allowing procedures to move a slower pace. Helpful advice is given, for instance, in the Equal Treatment Bench Book⁷. The CPS have produced draft guidance to assist prosecutors⁸ which, among other things, gives an overview of how to approach evidence and is helpful on fitness to plead, and on mens rea, which I touch on below.   

Given the brevity of this blog, my comments cannot be exhaustive.  

Criminal Matters 

People with schizophrenia are more likely to commit crime than the general population. Violent crime is increased by about 5 times, with about 1 in 4 men with schizophrenia or a related disorder getting a conviction for a violent offence⁹. It is likely that this increased risk related not only to the condition itself, but also the consequences of social adversity, especially co-morbid drug use. It is also important to recognise that, just like people without schizophrenia, most people with schizophrenia will not be convicted of a violent offence and most violent offences are committed by people without schizophrenia. Of interest is that in people without schizophrenia, there is a strong association between violence and cognitive impairment. Research trying to answer whether the risk of violence in people with schizophrenia is further compounded by cognitive impairment has been technically difficult and results have been contradictory.  While odd or unusual offences may relate to the presence of delusions or hallucinations, most of the time non-violent offences relate to poor decision making and limited social opportunities.   

The consideration of mens rea and schizophrenia can be especially problematic.  It is unusual that someone with schizophrenia is so unwell that they lack mens rea completely; far more common is the presence of impaired capacity for consequential thinking and diminished self-control rather than such a distortion of mind that they lack any capacity to form criminal intent. It may be that as our understanding of neuroscience develops that the construct of mens rea will need revisiting, although any consequent reductionist approach to human behaviour is foreseeably fraught with peril - philosophical, practical and ethical as well as legal.   

Civil Matters 

Impaired capacity to manage affairs, relationships and property are all seen more commonly in people with schizophrenia and can lead to matters coming before a court. Again, while dramatic positive symptoms can drive these kind of problems – paranoid persecutory beliefs about the neighbours interfering with the wiring leading to it being ripped out, for instance - usually disorganisation, difficulty in sequencing tasks, forgetfulness and inattention - all examples of cognitive impairment - are more prosaic explanations.   

Driving is an area that needs a little more comment. The risk of accidents is about double in this patient group¹⁰.  People with schizophrenia are obliged to report their diagnosis to the DVLA who then decide about fitness to drive. Clinical experience is that this rarely happens; it also appears that doctors are not very good at assessing fitness to drive when the DVLA ask about it, relying on reports or observations of gross sedation or inattention rather than assessing the more subtle impairments in attention and executive function that persist even when positive symptoms are treated successfully. They appear to make little use of driver assessment centres and knowledge among at least one group of UK doctors about relevant law and obligations was poor¹¹.  Legal professionals involved in assessment of consequences of an accident might wish to bear this in mind.  

Specific Legislation 

There are two pieces of legislation that bear upon the care, treatment and broader welfare of people with schizophrenia. These are the Mental Capacity Act and the Mental Health Act. Tensions exist between the two on occasion about what might be the best legal framework for detention and consequent deprivation of liberty and recently pockets of cases have arisen that seem quite at odds with usual practice and appear to be driven by quirks in the local training processes for mental health professionals. Sadly, I have had experience very recently of a Mental Health Act treatment order being used solely to ensure compliance with treatment for physical, as opposed to mental disorder - unlawful in itself in this case- in a patient who, after careful application of Principle 2 of the Mental Capacity Act Code of Practice, clearly had capacity concerning treatment for their lung disease. Cognitive impairments can underpin problems with compliance with treatment regimes, lack of insight and lack of consequential thinking - often misdescribed as bloody-mindedness or an oppositional stance – and leads to a repeated cycle of admission, treatment and breakdown. 

Schizophrenia can have an impact on testamentary capacity, although few sufferers have contact with solicitors to help them manage their estate for a range of reasons, and capacity to grant Lasting Powers of Attorney.  Florid delusions and hallucinations are easy to recognise as having an impact; cognitive impairments are less easy to recognise unless they are borne in mind.  

Final Word  

It was my intention in writing this blog to bring to your attention recent and upcoming changes in how we think about schizophrenia and to the importance of cognitive impairment for overall prognosis, and how it may affect the interface of this condition and the law. Thank you for your attention.  

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