Abstract
Background
Schizophrenia is a psychiatric disorder characterized by a deficit in reality testing, most often manifest in the form of delusions and hallucinations. Because differentiating real from imagined experiences is critically dependent on episodic and associative memory, deficits in mnemonic processes could be involved in the genesis of impaired reality testing. Prior work has shown that individuals with psychosis exhibit impairment in metamemory, or, awareness and knowledge of one’s own memory and memory processes, and that these impairments may be relevant to the emergence and/or maintenance of psychotic symptoms.
Methods
In the present study, we used a verbal associative memory paradigm incorporating subject confidence ratings to examine differences in metamemory processes in three separate samples: patients with chronic schizophrenia (CHR; n = 34), patients with recent-onset (first-episode) psychosis (n = 49), and individuals at clinical high risk for psychosis (n = 29) compared to control groups (n = 24, n = 26, and n = 22, respectively). We used an analysis of variance design to examine group differences in confidence gap and knowledge corruption between patients and controls. We further assessed the association of both of these metrics to symptom severity in each patient sample.
Results
We found that both chronic and first-episode patients displayed significantly decreased confidence gap compared to healthy controls, with patients being more confident in incorrect memory retrievals and less confident in correct memory retrievals as compared to healthy controls. Additionally, compared to healthy controls, chronic patients and first-episode patients showed significantly increased knowledge corruption (the proportion of confident incorrect memory retrievals compared to all confident retrievals). While there were no group differences in confidence gap and knowledge corruption between CHR subjects and healthy controls, decreased confidence gap was significantly correlated with positive symptom severity in CHR subjects, as well as in first-episode subjects.
Discussion
These findings suggest that underlying deficits in metamemory processes may possibly reflect mechanisms involved in the development and/or maintenance of disrupted reality testing in those with and at risk for psychosis.
Differential of Frequency and Duration Mismatch Negativity and Theta Power Deficits in First-Episode and Chronic Schizophrenia