Verbal and visual memory: characterizing the clinical and intermediate phenotype in schizophrenia

Area of Science:

• Neuroscience
• Psychiatry
• Cognitive Psychology

Background:

• Verbal and visual memory deficits are recognized trait markers in schizophrenia.
• These impairments are also present in first-degree relatives, suggesting a potential genetic link.
• It remains unclear if these deficits involve memory encoding or savings, and their heritability.

Purpose of the Study:

• To identify specific memory performance features impaired in both schizophrenia patients and their healthy siblings.
• To investigate potential shared genetic effects underlying these memory impairments.
• To differentiate between trait-like and state-dependent memory deficits in schizophrenia.

Main Methods:

• Episodic memory was assessed using Logical Memory (LM) and Visual Reproduction (VR) tasks from the Wechsler Memory Scale (Revised).
• Participants included patients with schizophrenia (n=162), their nonpsychotic siblings (n=146), and controls (n=205).
• Immediate encoding, 30-minute and 24-hour delayed recall, and savings scores were evaluated.

Main Results:

• Both patients and siblings exhibited significant verbal recall deficits compared to controls across all memory stages.
• Patients, but not siblings, showed significant verbal and visual savings deficits over short and long delays.
• No savings score difficulties were observed in siblings for either verbal or visual memory.

Conclusions:

• Shared impairment in verbal learning, not memory, between patients and siblings suggests it as a potential schizophrenia-associated intermediate phenotype.
• Deficits in immediate encoding and memory stabilization implicate neural systems involved in genetic risk for schizophrenia.
• Visual recall and savings impairments appear to be illness-specific (state) deficits rather than trait markers.