Impact of Cognitive Disturbances and Clinical Symptoms on Disability in Patients with Paranoid Schizophrenia: A Study of a Bulgarian Clinical Sample

The study aimed to assess the impact of clinical symptoms and cognitive impairment on disability in patients with paranoid schizophrenia (PS). Methods: 108 patients with schizophrenia were included (66 male and 42 female). Their average age was 38.86 ± 10.02 years and the disease duration was 12.80 ± 8.20 years, with mean disease onset of 24 years. Clinical symptoms were assessed with the PANSS, and cognitive performance was measured using a seven-item neurocognitive battery. The disability level of the subjects was assessed using the World Health Organization—Disability Assessment Schedule 2.0 (WHO-DAS 2.0). The relation between the variables studied was assessed using Spearman’s rank correlation coefficient (r(s)) at a probability level of p < 0.05. Results: An increase in symptom severity resulted in worsening of the “participation in society” (r = 0.56, p < 0.01), “life activities—household” (r = 0.55, p < 0.01), and “getting along with people” (r = 0.59, p < 0.01) WHO-DAS 2.0 domains. Positive symptoms (13.89 ± 3.48) correlated strongly with “getting along with people” (r = 0.55, p < 0.01), “life activities—household” (r = 0.58, p < 0.01), and “participation in society” (r = 0.62, p < 0.01), and negative symptoms (14.25 ± 4.16) with “participation in society” (r = 0.53, p < 0.01) and “life activities—household” (r = 0.48, p < 0.01). Symptoms of disorganization (15.67 ± 4.16) had the highest impact on “life activities—household” (r = 0.81, p < 0.01), “getting along with people” (r = 0.56, p < 0.05), and “participation in society” (r = 0.65, p < 0.01). Episodic memory (r = −0.28, p < 0.01) was remotely related to comprehension and communication. The information processing speed (r(s) = 0.38, p < 0.01), visual memory (r(s) = −0.30, p < 0.01), and focused executive functions showed moderate correlations with all domains on the WHO-DAS 2.0 scale (r(s) = 0.38, p < 0.01). Attention (r(s) = −0.33, p < 0.01) was moderately related to community activities. Semantic (r(s) = −0.29, p < 0.01) and literal (r(s) = −0.27, p < 0.01) verbal fluency demonstrated weak correlations with “cognition—understanding”, “getting along with people”, and “participation in society”. Conclusion: Symptoms of disorganization and disturbed executive functions contribute most to disability in patients with schizophrenia through impairment of real-world functioning, especially in social interactions and communication. Severe clinical symptoms (negative and disorganization-related ones) as well as deficits in executive function, verbal memory, and verbal fluency cause the biggest problems in the functional domains of interaction with other people and participation in society.