Schizophrenia in ICD-11: diagnosis, symptoms and key changes from ICD-10

Schizophrenia in ICD-11 - code 6A20 and the primary psychotic disorders group

In ICD-11, schizophrenia is placed in the group called schizophrenia or other primary psychotic disorders. The term "primary" means that psychotic symptoms are the central element of the clinical picture rather than only a secondary effect of another condition, such as a depressive episode, mania, psychoactive substance use, medication or a neurological illness.^[3]

The essence of schizophrenia is persistent psychotic symptoms such as delusions, hallucinations, disorganised thinking and speech, experiences of influence, passivity or control, negative symptoms and psychomotor disturbances. These symptoms must be assessed in the context of duration, impact on functioning and differential diagnosis.^[4]

The same ICD-11 group also includes other primary psychotic disorders, including schizoaffective disorder (6A21), schizotypal disorder (6A22), acute and transient psychotic disorder (6A23) and delusional disorder (6A24). This means that the presence of psychotic symptoms alone is not enough to diagnose schizophrenia. It is necessary to determine which type of psychotic disorder best explains the patient's presentation.

The most important change from ICD-10 - the end of classical schizophrenia subtypes

One of the most important changes in ICD-11 is the removal of classical schizophrenia subtypes. ICD-10 included paranoid, hebephrenic, catatonic, undifferentiated, residual and simple schizophrenia, among others. In clinical practice these subtypes gave an impression of greater precision, but they were often not stable over time.

The problem was that the presentation of schizophrenia can change. A person who mainly has delusions and hallucinations in one period may later have more prominent negative symptoms, behavioural disorganisation or cognitive difficulties. The former subtype therefore described a current cross-section of symptoms rather than a stable, prognostically useful type of disorder. Literature on the transition from ICD-10 to ICD-11 emphasises that limited longitudinal stability and insufficient prognostic value were among the reasons for removing the subtypes.

ICD-11 therefore moves away from the question: "which subtype of schizophrenia is this?". Instead, it asks: what is the course of the disorder, what is the patient's current state, and which symptom domains are most prominent. This approach better matches clinical practice because it allows the description to be updated as the patient's state changes.

Comparison table: ICD-10 vs ICD-11

The main difference is therefore not that ICD-11 completely changed the definition of schizophrenia, but that it changed the way schizophrenia is clinically described. Former subtypes were replaced by an approach that better shows the patient's current state, course history and dominant difficulties.

Diagnostic requirements - what must be present?

ICD-11 describes schizophrenia through a characteristic set of psychotic symptoms rather than a simple list of rigid subtypes. Diagnosis requires at least two characteristic symptoms present for most of the time for at least one month. At least one of them should belong to the key symptom group, such as persistent delusions, persistent hallucinations, disorganised thinking, or experiences of influence, passivity or control.

The time threshold of at least one month protects against a premature schizophrenia diagnosis in brief psychotic episodes. If symptoms are sudden, brief and resolve quickly, the picture may fit acute and transient psychotic disorder better. If psychotic symptoms are closely linked to a depressive or manic episode, differential diagnosis with mood disorders with psychotic symptoms or schizoaffective disorder is necessary.

Assessment of the impact on functioning is also important. Schizophrenia symptoms usually disrupt relationships, work, study, self-care or everyday coping. The symptom description should not be interpreted outside its clinical, cultural, developmental and somatic context. Other causes also have to be excluded, including neurological diseases, psychoactive substances, medications and somatic conditions that can cause psychotic symptoms.

Positive symptoms, negative symptoms, disorganisation and psychomotor symptoms

Positive symptoms are phenomena that appear in addition to typical mental experience. They include delusions, hallucinations, disorganised thinking and experiences of influence, passivity or control. Delusions are fixed beliefs inconsistent with reality and resistant to rational argument. Hallucinations are perceptions without a real external stimulus, most often hearing voices. Disorganised thinking may appear as speech that is hard to follow, illogical thought flow or loss of coherence.

Negative symptoms involve weakening or loss of functions present in healthy functioning. They may include blunted affect, reduced facial expression, limited voice modulation, reduced motivation, social withdrawal, poverty of speech, anhedonia and difficulty initiating activity. They are often less dramatic than delusions or hallucinations, but can strongly affect independence and social functioning.

Disorganised behaviour may include behaviour inappropriate to the situation, difficulty carrying out basic activities, unpredictability, marked deterioration in self-care or highly inconsistent emotional reactions. Psychomotor symptoms may include slowing, agitation, bizarre postures, mannerisms, stupor or other disturbances of motor activity. If the presentation meets the requirements for catatonia, ICD-11 allows it to be coded separately.

Course specifiers - a new descriptive tool in ICD-11

ICD-11 allows the course of schizophrenia to be specified more precisely. This is one of the most practical changes from ICD-10 because it communicates not only the diagnosis itself, but also the clinical history and the patient's current state. WHO describes course specifiers as a way to indicate whether the current episode is the first episode, whether previous episodes have occurred, whether the course is continuous, and whether the patient is currently symptomatic, in partial remission or in full remission.

In ICD-11, one can describe for example:

First episode - when symptoms meet the diagnostic requirements for schizophrenia for the first time.

Multiple episodes - when another episode meeting diagnostic requirements occurs after a previous episode and a period of improvement.

Continuous course - when symptoms persist for all or almost all of the duration of the disorder, without clear periods of remission.

Each pattern can be combined with current status: currently symptomatic, partial remission or full remission. For example, "schizophrenia, multiple episodes, full remission" describes a different clinical situation than "schizophrenia, first episode, currently symptomatic". The former subtype system did not convey such precise information about the patient's current place in the course of illness.

Dimensional description of symptoms - six severity domains

Alongside the diagnosis and course specifier, ICD-11 allows a dimensional description of symptom severity. In practice, six domains can be considered: positive symptoms, negative symptoms, depressive symptoms, manic symptoms, psychomotor symptoms and cognitive symptoms. Each domain can be assessed for severity.

The clinical importance of this description is substantial. Two people may have the same schizophrenia diagnosis but very different difficulty profiles. One may have dominant delusions and hallucinations, another mainly negative and cognitive symptoms, and a third psychomotor symptoms or co-occurring mood symptoms. The same main code therefore does not mean the same clinical profile or the same therapeutic needs.

The dimensional approach helps plan management. If cognitive symptoms dominate, assessment of attention, memory, planning and executive functioning may be important. If negative symptoms dominate, support for activation, relationships and daily functioning becomes central. If positive symptoms dominate, treating psychosis, safety and reducing disorganisation may be priorities.

Catatonia in ICD-11 - separate syndrome, not a schizophrenia subtype

In ICD-10, catatonia was mainly associated with catatonic schizophrenia. ICD-11 moves away from this view. Catatonia is no longer a subtype of schizophrenia, but a separate clinical syndrome that can occur in different contexts: schizophrenia, mood disorders, other mental disorders, somatic illnesses or substance-related states.

If a full catatonic syndrome occurs in a person with schizophrenia, both schizophrenia and catatonia associated with another mental disorder, for example 6A40, can be coded. This is an important change because catatonia requires separate assessment and may require specific management regardless of the primary diagnosis.

Clinically, this means that catatonia is no longer treated as a "kind of schizophrenia". It is a separate dimension of the clinical picture that may appear in various disorders and medical states.

Differential diagnosis of schizophrenia

Psychotic symptoms are not specific only to schizophrenia, so differential diagnosis is a necessary part of assessment. It is especially important to distinguish schizophrenia from schizoaffective disorder, delusional disorder, acute and transient psychotic disorder, mood disorders with psychotic symptoms, PTSD, CPTSD, dissociative disorders, substance-induced disorders, and neurological or somatic diseases.

Schizoaffective disorder (6A21) is considered when schizophrenic symptoms and a mood episode occur together in a way that meets diagnostic requirements. If psychotic symptoms appear only during a depressive or manic episode, a mood disorder with psychotic symptoms may be more appropriate.

Delusional disorder (6A24) is characterised by dominant persistent delusions without the full picture of schizophrenia. Acute and transient psychotic disorder (6A23) usually differs by shorter duration and greater symptom variability. PTSD and CPTSD may include flashbacks, dissociation, hypervigilance and experiences that superficially resemble psychosis, but their relationship to trauma and post-traumatic mechanisms requires separate assessment.

In a first psychotic episode, it is particularly important to exclude psychoactive substances, withdrawal states, medication adverse effects, neurological diseases, infections, metabolic disturbances and other somatic conditions. This is why schizophrenia should not be diagnosed solely on the basis of a single symptom such as hallucinations or suspiciousness.

Cultural context and risk of misdiagnosis

ICD-11 notes that diagnosing schizophrenia requires attention to cultural context. Religious beliefs, spiritual experiences, cultural practices, metaphorical language of distress or different ways of expressing emotion should not automatically be considered psychotic symptoms. What matters is whether the experience is understandable in the context of the patient's culture, religion, language and environment.

Particular caution is needed when assessing a person through an interpreter or in a language that is not their first language. Unusual metaphors, limited fluency, defensiveness or mistrust of institutions can be wrongly interpreted as disorganisation, delusions or paranoia. A mistaken schizophrenia diagnosis has serious consequences, so cultural and language history should be a regular part of clinical assessment.

Schizophrenia in children - very rare, particular caution

Full-symptom onset of schizophrenia before puberty is very rare. In children, psychotic symptoms are especially easy to confuse with other phenomena: developmental imagination, childhood fears, neurodevelopmental disorders, trauma responses, mood disorders or communication difficulties.

Fear of a "monster under the bed", an imaginary friend, magical thinking or fantasy play are not in themselves symptoms of schizophrenia. Clinical assessment must take into account age, developmental stage, family context, school functioning, change from previous functioning and possible neurological or somatic illnesses.

If a child shows actual psychotic symptoms such as persistent hallucinations, delusions, marked behavioural disorganisation or clear deterioration in functioning, urgent specialist assessment is required. Even then, a schizophrenia diagnosis in a child should be made with exceptional caution.

What schizophrenia does not mean - debunking myths

Many harmful myths surround schizophrenia. The first is confusing schizophrenia with "split personality". Schizophrenia does not mean alternating between different persons. It primarily concerns disturbances in contact with reality, thinking, perception, affect, motivation and functioning.

The second myth links schizophrenia with automatic danger and aggression. This image is reinforced by popular culture, but it is simplified and stigmatising. Most people diagnosed with schizophrenia do not pose a threat to others. In crisis situations, they more often need support, treatment and protection themselves.

The third myth assumes that schizophrenia always means inevitable progressive decline. ICD-11 allows partial and full remission to be specified, and many people can function, maintain relationships and pursue important goals with appropriate treatment and support. The diagnosis describes the disorder and its course, but it is not a verdict or a full description of the person.

The diagnostic process and when to seek help

Schizophrenia is diagnosed by a psychiatrist or another qualified specialist in the relevant care system, on the basis of a full clinical assessment. Such assessment includes history of symptoms, their onset, duration, impact on functioning, previous episodes, treatment, substance use, somatic illnesses, neurological illnesses, medications and information from relatives if the patient consents or if the situation requires it.

Urgent consultation is especially needed for: hearing voices, strong and increasing suspiciousness, beliefs clearly detached from reality, disorganised speech, marked withdrawal, self-care neglect, a feeling of losing control over one's thoughts or behaviour, and behaviours threatening safety.

In a situation of immediate danger to life or health - one's own or another person's - urgent help should be sought immediately.

Frequently asked questions