What are the positive and negative symptoms of schizophrenia?

Positive and Negative Symptoms of Schizophrenia

Schizophrenia is characterized by two distinct symptom clusters: positive symptoms, which represent an excess or distortion of normal functions (hallucinations, delusions, thought disorder), and negative symptoms, which represent a diminution or absence of normal behaviors and functions (avolition, anhedonia, asociality, blunted affect, and alogia).

Positive Symptoms

• Hallucinations: Sensory perceptions that occur without external stimulation, most commonly auditory (hearing voices) but can also be visual, tactile, olfactory, or gustatory 1
• Delusions: Fixed false beliefs that persist despite contradictory evidence; common types include persecutory, referential, and grandiose delusions 1
• Thought disorder: Disorganized thinking manifested through loose associations, tangentiality, and illogical reasoning 1
• Disorganized speech: Incoherent communication, derailment, or word salad 2
• Disorganized behavior: Unpredictable or inappropriate actions, bizarre mannerisms, or catatonia 2

Negative Symptoms

Negative symptoms cluster into two main factors:

Experiential Factor

• Avolition: Reduction in goal-directed activity due to decreased motivation 3, 4
• Anhedonia: Reduced ability to experience pleasure from activities normally found enjoyable 3, 4
• Asociality: Diminished interest in or desire for social interactions 3, 4

Expressive Factor

• Blunted affect: Reduced emotional expressiveness, including limited facial expressions, monotone voice, and decreased spontaneous movements 3, 4
• Alogia: Reduction in the quantity of speech and content of speech (poverty of speech) 3, 4

Clinical Significance of Negative Symptoms

• Negative symptoms affect up to 90% of people experiencing first-episode psychosis and persist in 35-70% of patients after treatment 3
• They represent a substantial burden for patients, causing significant impairment in:
  • Academic and occupational performance 3
  • Social functioning and participation in social activities 3
  • Quality of life 3
• Negative symptoms are associated with low remission rates and poorer long-term outcomes 3, 4

Primary vs. Secondary Negative Symptoms

• Primary negative symptoms: Intrinsic to the underlying pathophysiology of schizophrenia 3, 5
• Secondary negative symptoms: Related to other factors such as:
  • Positive symptoms 3
  • Depressive symptoms 3, 5
  • Medication side effects (particularly extrapyramidal symptoms) 3, 5
  • Environmental deprivation 3
  • Other treatment or illness-related factors 3

Clinical Challenges in Assessing Negative Symptoms

• Negative symptoms are often underdiagnosed as clinicians tend to focus on more pressing positive symptoms 3, 4
• Patients frequently lack insight into their negative symptoms, making assessment challenging 3, 4
• Distinguishing between primary and secondary negative symptoms is clinically difficult but crucial for treatment planning 3, 4

Treatment Response Patterns

• Positive symptoms generally respond well to antipsychotic medications 6, 7
• Negative symptoms, especially primary ones, have limited response to standard dopamine D2 antagonists or partial agonists 3, 4
• Among antipsychotics, cariprazine and amisulpride have shown the most promising results for negative symptoms 3, 4
• No antipsychotic medications currently have official FDA indication specifically for treating negative symptoms 4

Pitfalls in Clinical Practice

• Failing to assess for negative symptoms when positive symptoms are controlled 4
• Misattributing secondary negative symptoms (e.g., from depression or medication side effects) as primary negative symptoms 3
• Overlooking the significant impact of negative symptoms on functional outcomes 3, 4
• Not recognizing that negative symptoms may predate the onset of positive symptoms and can be present in prodromal phases 3