Using poverty of speech as a case study to explore the overlap between negative symptoms and cognitive dysfunction

Area of Science:

• Psychiatry and Neuroscience
• Clinical Psychology
• Speech and Language Pathology

Background:

• Negative symptoms and cognitive impairment are key prognostic indicators in schizophrenia.
• While often considered distinct, a conceptual overlap between these domains is suspected.
• Speech deficits in schizophrenia were investigated to illustrate this potential overlap.

Purpose of the Study:

• To examine the relationship between alogia (a negative symptom) and verbal fluency (a cognitive measure) in schizophrenia.
• To determine if speech deficits represent a shared construct between negative and cognitive symptoms.

Main Methods:

• Clinician ratings of alogia were used to assess negative symptoms.
• Verbal fluency tests, measuring word recall from categories, were used to assess cognitive impairment.
• Cross-sectional and longitudinal analyses examined the relationship between alogia and verbal fluency scores.

Main Results:

• More severe alogia was significantly associated with fewer words produced on verbal fluency tests.
• This association was stronger than with other negative symptoms and persisted after controlling for covariates.
• Improvements in verbal fluency scores longitudinally predicted improvements in alogia ratings.

Conclusions:

• Clinical ratings of alogia and performance on verbal fluency tests tap into a similar underlying construct.
• This suggests that some negative symptoms are not fully distinct from cognitive impairments in schizophrenia.
• The classification of deficits as negative versus cognitive may be semantic rather than reflecting separate processes.