Treated, untreated schizophrenia characterized by impaired thinking

Patients with schizophrenia, regardless of medication, exhibit pervasive deficits in cognitive function, including the domains of reinforcement learning, processing speed, cognitive control, working memory, verbal learning, and relational encoding and retrieval, a study has shown.

The study included unmedicated (n=48) and medicated (n=148) patients and healthy controls (n=75). Unmedicated patients were younger than medicated patients and controls, while the medicated group had lower Wechsler Test of Adult Reading score. With respect to symptom variables, the unmedicated vs medicated group had more positive symptoms but less emotional blunting.

Compared with controls, patients with schizophrenia, both those who were not taking and not taking antipsychotic medications, performed poorly in the following cognitive tasks: cognitive domains including Explicit Probabilistic Incentive Learning Task (E-PILT), Letter Number Sequencing (LNS), Jittered Orientation Visual Integration Task (JOVI), BACS Symbol Coding, Dot Probe Expectancy Task (DPX), Running Span (O-Span), Hopkins Verbal Learning Test (HVLT), and Relational and Item-Specific Encoding (RiSE).

Of note, chlorpromazine equivalency rates were significantly associated with processing speed and working memory, whereas there were no relationships observed between anticholinergic load and performance on other tasks.

In some domains, the cognitive deficits were slightly more evident in medicated patients, especially on tasks that evaluated processing speed and verbal learning. The fact that unmedicated individuals had cognitive deficits in all of the same domains impaired in medicated individuals, even if in some cases to a slightly lesser degree, suggests that cognitive impairments are an enduring aspect of schizophrenia and present in those both on and off antipsychotic medications, according to researchers.