# 13 - Contrasting DSM IV and ICD 10

# Contrasting DSM-IV and ICD-10

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florid symptoms such as delusions and hallucinations have been minimal or substantially reduced 
and absence of organic brain disease or disorder”. 
 Post schizophrenic depression is classed under F20s. Some schizophrenic symptoms (mostly 
negative) must be present though not dominating the picture. The most recent episode of relapse 
must not be more than 12 months ago. If no current schizophrenic symptoms at all then depressive 
disorder can be diagnosed. If florid schizophrenia symptoms with minor affective disturbances 
noted, then relapse must be suspected. 
Contrasting DSM-IV and ICD-10 
 
ICD 10 
DSM IV 
Characteristic 
symptoms 
 
At least one of: 
1. Thought echo, thought 
insertion/withdrawal/broadcast 
2. Passivity, delusional perception 
3. Third person auditory hallucination, running 
commentary 
4. Persistent bizarre delusions 
 
OR two or more of: 
1. Persistent hallucinations 
2. Thought disorder 
3. Catatonic behaviour 
4. Negative symptoms 
5. Signiﬁcant  behaviour  change 
At least one of: 
1. Bizarre delusions 
2. Third person auditory hallucinations 
3. Running commentary 
 
OR two or more of: 
1. Delusions 
2. Hallucinations 
3. Disorganized speech 
4. Grossly disorganized behaviour 
5. Negative symptoms 
Duration 
More than 1 month 
1 month of characteristic symptoms 
With 6 months of social/occupational dysfunction 
Subtypes 
Paranoid 
Catatonic 
Hebephrenic 
Residual 
Undifferentiated 
Simple 
Postschizophrenic depression 
Paranoid 
Catatonic 
Disorganized 
Residual 
Undifferentiated 
Chapters 
• 
F20 Schizophrenia 
• 
F21 Schizotypal disorder 
• 
F22 Persistent delusional disorder 
• 
F23 Acute and transient psychotic 
disorders 
• 
F24 Induced delusional disorders 
• 
F25 Schizoaffective disorder 
• 
F28 Other non-organic psychotic disorders 
• 
F29  Unspeciﬁed  non-organic psychosis 
 
• 
295.x Schizophrenia 
• 
295.4 Schizophreniform disorder 
• 
295.7 Schizoaffective disorder 
• 
297.1 Delusional disorder 
• 
297.3 Shared psychotic disorder 
• 
298.8 Brief psychotic disorder 
• 
298.9 Psychotic disorder NOS

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Other ‘schizophrenias’ in ICD-10 
In acute and transient psychotic disorders (ICD-10), onset within two weeks is described as acute while 
the onset within 48 hours is called abrupt. Complete recovery 
within 2 to 3 months is the rule. It can be of polymorphic form or 
schizophrenia-like in it is presentation. In acute polymorphic 
psychosis, several hallucination and delusions changing in both 
type and intensity from day to day or even same day is noted. 
Schizotypal disorder is diagnosed in patients with eccentric 
manners, social withdrawal, magical thinking, suspiciousness, 
and obsessive ruminations but without resistance. The 
ruminations may have dysmorphophobic contents too. At least a 
2-year history with schizophrenia being never diagnosed in the 
past is necessary for diagnosing schizotypal disorder. Schizotypal 
disorder includes older descriptions such as borderline 
schizophrenia, pseudo neurotic schizophrenia, etc. Is classified 
along with schizophrenia and related disorders in ICD-10 but 
along with Cluster A personality disorders in DSM-4. Schizotypy 
is more common in the other first-degree relatives of 
schizophrenic subjects than in the general population and the 
relatives of schizotypal subjects have an increased risk of 
schizophrenia. 
Persistent delusional disorders are characterised by a persistent, 
often life-long, typically  ‘non-bizarre’ delusion or a set of related 
delusions arising insidiously in mid-life or later. Transient 
auditory hallucinations may occur, but clear and persistent auditory hallucinations (voices), schizophrenic 
symptoms such as delusions of control and marked blunting of affect, and definite evidence of brain 
disease are incompatible with 
this diagnosis. However, the 
presence of occasional or 
transitory auditory 
hallucinations, particularly in 
elderly patients, does not rule 
out this diagnosis. The 
delusions need not be strictly 
monothematic though this is 
mostly the case. Affect, thought 
and behaviour are globally 
normal, but  patients’  attitudes  
Schizophrenia 
Delusional Disorder 
Bizarre delusions are common 
Non-bizarre delusions (cannot be 
bizarre by ICD-10 definition) 
Daily functioning is significantly 
impaired 
Daily functioning is not 
significantly impaired 
Apart from delusions may have one 
or more of the following: 
x Hallucinations 
x Disorganized speech 
x Disorganized behaviour 
x Negative symptoms 
 
These symptoms are almost 
always absent (tactile or olfactory 
hallucinations if at all present, are 
entangled in the content of a 
delusional complex) 
DSM-5 AND SCHIZOPHRENIA 
Presence of bizarre delusions or 
hallucinations is no longer sufficient as a 
sole criterion A for diagnosing 
schizophrenia. 
2  of  5  ‘criterion-A’  symptoms  required  for  a  
diagnosis with at-least one being a core 
positive symptom (delusions, hallucinations 
or disorganized speech) 
Schizophrenia subtypes (paranoid, 
disorganized, catatonic, undifferentiated, 
and residual types) have been removed. 
A dimensional method of rating severity for 
the core symptoms of schizophrenia is 
included. This proposes 8 dimensions 
(delusions, hallucinations, depression, 
mania, abnormal cognition, abnormal 
psychomotor behavior, disorganized speech 
and negative symptoms)

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and actions in response to these delusions are appropriate and 
may lead to dangerousness in some cases. Symptoms should 
have been present for at least 1 month (DSM-IV). ICD-10 
specifies at least 3 months for delusional disorder. According to 
DSM-IV delusional disorder – ‘Apart from the impact of the 
delusion(s) or its ramifications, functioning is not markedly 
impaired, and behaviour  is  not  obviously  odd  or  bizarre’.  This  
criterion is not explicit in ICD-10. 
 
 
 
 
DSM-IV subtypes of delusional disorders 
Type 
Description 
Erotomania (de 
Clerambault 
syndrome) 
An erotic conviction that a person with higher status is secretly in love with the patient 
Seen most often in women though forensic samples are mostly males; may be associated with 
stalking or assaultive behaviour 
Grandiosity 
Patients believe they fill some special role, have some special relationship, or possess some 
special abilities. They may be involved with social or religious organisations 
Jealousy (Othello 
syndrome) 
Characterised by a delusion of infidelity. Patients possess the fixed belief that their spouse or 
partner has been unfaithful. Often patients try to collect evidence and/or attempt to restrict 
their partner's activities. Contributes to both wife battering and homicide. 
Persecutory 
Most common form of the delusional disorder. Patients are often convinced that others are 
attempting to hurt or harm them. This leads to them trying to obtain legal recourse, and 
sometimes turning violent. 
Somatic 
Varying presentations including patients who have repeated medical consultations requesting 
several treatment to those that show delusional concerns about a bodily infestation, deformity 
(delusional dysmorphophobia) or odour. 
 
Mixed and 
unspecified types 
Please refer to delusional misidentification syndromes in Descriptive Psychopathology notes 
 
Induced delusional disorders are accepted as a distinct diagnostic category and coded as F24 in ICD-10. 
This is a rare delusional disorder characterised by sharing of delusions between usually 2 or occasionally 
more persons who often have tightly knit emotional bonds. Only one person has genuine delusions due to 
underlying psychiatric disorder, most often schizophrenia or delusional disorder. On separation, the 
dependent individual may give up his or her delusions and the patient with the genuine delusions should 
be treated appropriately. In induced delusional disorders, induced hallucinations can be present, and this 
DSM-5 AND DELUSIONAL 
DISORDERS 
There is no requirement for delusions to be 
non-bizarre anymore 
Delusional symptoms must not be better 
explained by conditions such as obsessivecompulsive or body dysmorphic disorder 
with absent insight/delusional beliefs. 
Shared delusional disorder is no longer a 
separate diagnosis.