F20

Schizophrenia is a severe and chronic psychiatric disorder classified under F20 in the ICD-10 (International Classification of Diseases, 10th Revision). It is characterized by profound disruptions in thinking, perception, emotions, and behavior. The disorder often leads to significant social and occupational dysfunction, affecting approximately 1% of the global population. Schizophrenia typically emerges in late adolescence or early adulthood and follows a variable course with remissions and relapses.

This article provides a detailed and comprehensive review of schizophrenia, including its symptoms, diagnostic criteria, differential diagnosis, and assessment methods, making it a valuable resource for both medical professionals and the general public.

Symptoms

Schizophrenia manifests through a combination of positive symptoms, negative symptoms, cognitive impairments, and affective disturbances. The presentation varies significantly among individuals.

1. Positive symptoms

These symptoms represent an excess of normal functioning and are often the most noticeable.

• Hallucinations – False sensory perceptions without external stimuli.
  • Auditory hallucinations (most common) – Hearing voices, whispers, or noises.
  • Visual hallucinations – Seeing non-existent figures, shadows, or distortions.
  • Olfactory, gustatory, and tactile hallucinations – Rare but can include experiencing unusual smells, tastes, or sensations on the skin.
• Delusions – Firmly maintained beliefs that are untrue and persist despite logical evidence to the contrary.
  • Paranoid delusions – Belief that one is being watched, followed, or persecuted.
  • Delusions of reference – Thinking that random events, TV shows, or songs contain hidden messages directed at the individual.
  • Grandiose delusions – Belief in having special powers, knowledge, or identity (e.g., thinking one is a deity or world leader).
  • Somatic delusions – Belief in having a serious illness despite medical reassurance.
• Disorganized Thinking (Formal Thought Disorder) – Impairments in logical reasoning and coherent speech.
  • Tangentiality – Jumping between unrelated topics.
  • Derailment (Loosening of associations) – Losing track of thoughts and making illogical connections.
  • Neologisms – Inventing new, meaningless words.
  • Word salad – Incoherent and nonsensical speech.
• Disorganized or Catatonic Behavior
  • Unpredictable agitation or inappropriate behavior
  • Bizarre postures, mutism, or extreme negativism
  • Waxy flexibility – Remaining in an unusual posture for long periods.

2. Negative symptoms

Negative symptoms contribute significantly to disability and functional impairment.

• Alogia – Reduced speech output, giving brief or monosyllabic responses.
• Avolition – Lack of motivation, difficulty in initiating and sustaining activities.
• Anhedonia – Reduced ability to experience pleasure in normally enjoyable activities.
• Flat Affect – Limited emotional expression (monotone speech, reduced facial expressions).
• Social Withdrawal – Avoidance of social interactions, difficulty forming relationships.

3. Cognitive impairments

Cognitive deficits are present in most individuals with schizophrenia and significantly impact daily functioning.

• Impaired working memory – Difficulty holding and manipulating information.
• Executive dysfunction – Poor decision-making, planning, and problem-solving.
• Impaired attention and concentration – Difficulty focusing on tasks or conversations.
• Poor insight – Lack of awareness of the illness (anosognosia).

4. Affective symptoms

Although schizophrenia is primarily a psychotic disorder, mood disturbances can be present.

• Depressive symptoms – Low mood, guilt, suicidal thoughts.
• Anxiety symptoms – Paranoia-related distress or general unease.
• Emotional dysregulation – Sudden mood shifts, inappropriate emotional reactions.

Diagnostic criteria

According to the ICD-10, the diagnosis of schizophrenia requires at least one very clear symptom from Group A or at least two symptoms from Group B, lasting for at least one month.

Group A: core symptoms (at least one required)

1. Thought echo, insertion, withdrawal, or broadcasting
   • Belief that thoughts are being controlled, removed, or broadcasted to others.
2. Delusions of control, influence, or passivity
   • Feeling controlled by external forces affecting actions, thoughts, or sensations.
3. Auditory hallucinations
   • Voices commenting on behavior, conversing, or giving commands.
4. Bizarre delusions
   • Implausible, culturally inappropriate delusions.

Group B: additional symptoms (at least two required)

1. Persistent hallucinations in any modality
2. Disorganized speech (incoherence, neologisms, derailment)
3. Severe disorganized or catatonic behavior
4. Negative symptoms (apathy and abulia, anhedonia, blunted affect, alogia)
5. Significant social or occupational dysfunction

If these symptoms persist for at least six months, a diagnosis of chronic schizophrenia may be considered.

Differential diagnosis

Schizophrenia shares symptoms with many other conditions. A careful differential diagnosis is essential.

Condition	Key Differences from Schizophrenia
Schizoaffective Disorder (F25)	Prominent mood episodes (mania/depression) along with psychotic symptoms.
Bipolar Disorder with Psychotic Features (F31.2, F31.5)	Mood symptoms are primary; psychotic symptoms occur during mood episodes.
Major Depressive Disorder with Psychotic Features (F32.3, F33.3)	Delusions/hallucinations occur only during severe depressive episodes.
Delusional Disorder (F22)	Isolated delusions without significant thought disorder or hallucinations.
Autism Spectrum Disorder (F84.0-F84.9)	Present from early childhood; lack of hallucinations and delusions.
Substance-Induced Psychotic Disorder (F19.5)	Psychosis linked to drug use or withdrawal.
Neurological Conditions (e.g., Temporal Lobe Epilepsy, Dementia, Brain Tumors)	Neurological signs (seizures, cognitive decline, or imaging abnormalities).

Also health specialists may consider:

Metabolic disorders:

• Thyroid dysfunction
• Wilson’s disease
• Porphyria
• Vitamin B12 deficiency
• Autoimmune disorders

Diagnostic methods and evaluation

1. Clinical Interview – Comprehensive psychiatric history and symptom assessment.
2. Mental Status Examination (MSE) – Evaluating thought processes, speech, perception, and cognition.
3. Neuroimaging (MRI/CT Scan) – Rule out structural brain abnormalities.
4. Electroencephalogram (EEG) – Assess for epilepsy or abnormal brain activity.
5. Laboratory Tests – Rule out infections, metabolic disorders, or substance use.
6. Psychological Testing (PANSS, SANS, SAPS) – Assess positive and negative symptoms.

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