Positive and Negative Symptoms of Schizophrenia
Schizophrenia manifests through two distinct symptom clusters: positive symptoms (hallucinations, delusions, disorganized thoughts and behavior) and negative symptoms (avolition, anhedonia, asociality, blunted affect, and alogia), with negative symptoms carrying substantially greater functional burden and affecting 40% of patients prominently. 1, 2
Positive Symptoms
Positive symptoms represent an excess or distortion of normal functions and include:
Hallucinations: Predominantly auditory in nature, with voices commenting on one's actions or voices conversing with each other representing first-rank symptoms 2, 3. Visual hallucinations are less characteristic of schizophrenia and should prompt consideration of alternative diagnoses such as dementia with Lewy bodies or substance-induced disorders 3.
Delusions: Fixed false beliefs that are present in excess compared to individuals without schizophrenia 2. Systematic delusions may be less frequent in early-onset presentations 4.
Disorganized thoughts and behavior: Including thought disorder characterized by loose associations, illogical thinking, and impaired discourse skills 4, 2. Thought withdrawal (the experience that thoughts are being removed from one's mind) represents a classic first-rank symptom of thought possession 3.
Agitation: Representing behavioral dysregulation associated with the acute phase of illness 2.
Negative Symptoms: The Five Core Domains
Negative symptoms involve a lessening or absence of normal behaviors and functions, comprising five key constructs:
Avolition: Reduced goal-directed activity due to decreased motivation 1, 2, 5. This represents impairment in the volitional domain and is a primary driver of functional disability 6.
Anhedonia: Reduced capacity to experience pleasure 1, 2, 5. This affects both anticipatory and consummatory pleasure experiences 6.
Asociality: Social withdrawal and reduced social engagement 1, 2, 5. This manifests as decreased interest in social interactions and relationships 6.
Blunted affect: Reduced emotional expression and flattened affect 1, 2, 5. This includes diminished facial expressiveness and vocal intonation 7.
Alogia: Poverty of speech, representing reduction in the quantity of words spoken 1, 2, 5. This reflects impoverished verbal communication 7.
Clinical Significance and Prevalence
Up to 90% of patients experiencing first-episode psychosis present with at least one negative symptom, and these persist in 35-70% of patients after treatment 1.
Negative symptoms are associated with low remission rates, impaired academic and occupational performance, and poor social functioning 1.
Approximately 60% of patients may have prominent clinically relevant negative symptoms requiring treatment 5.
Negative symptoms are reported as the most common first symptom of schizophrenia and can occur at any point in the illness course 5.
Temporal Evolution and Symptom Patterns
The prodromal phase precedes psychotic symptoms with social withdrawal, idiosyncratic preoccupations, unusual behaviors, academic failure, deteriorating self-care, dysphoria, anxiety, or physical complaints 2.
The acute phase is marked by predominance of positive symptoms with significant functional deterioration, typically lasting 1-6 months 2.
Symptoms tend to shift from positive to negative over time in the illness course, with the residual phase involving prolonged periods between acute episodes with ongoing negative symptom impairment 2.
Primary vs. Secondary Negative Symptoms: Critical Distinction
Primary negative symptoms are intrinsic to the underlying pathophysiology of schizophrenia and generally do not respond well to currently available dopamine D2 antagonist antipsychotics 5, 6.
Secondary negative symptoms result from:
- Unrelieved positive symptoms 6, 7
- Comorbid depression 6, 7
- Adverse effects of antipsychotics (particularly extrapyramidal symptoms) 6, 7
- Substance abuse 6
- Social isolation or environmental deprivation 6, 7
Secondary negative symptoms can improve with treatment of the underlying cause, whereas primary negative symptoms represent a persistent and treatment-resistant dimension requiring specialized interventions 5, 6.
Assessment Considerations
Standardized rating scales such as the Positive and Negative Syndrome Scale (PANSS), Scale for the Assessment of Negative Symptoms (SANS), or Scale for the Assessment of Positive Symptoms (SAPS) should be used to measure symptom severity 4, 1.
Patients may lack insight about the presence of negative symptoms, so these are generally not the reason patients seek clinical care, requiring clinicians to be especially vigilant for their presence 5.
Developmental differences in language and cognition affect symptom presentation in children and adolescents, requiring differentiation of thought disorder from developmental delays or language disorders 4, 2.