Dyslexia and risk of future violence in forensic psychiatric patients

Sammanfattning: The thesis consists of three studies. The main aim was to increase knowledge about dyslexia in forensic psychiatric patients and about how dyslexia is related to risk of future violence. In Study I, the prevalence of dyslexia was assessed by using different criteria, and the results showed that 17-53% of the patients met discrepancy criteria for dyslexia, while 50% had poor phonological processing skills and met the phonological core criterion for dyslexia. Poor phonological processing skills are believed to be the underlying cause of dyslexia. The results from Study I suggest that the patients’ phonological processing skills are not related to disadvantageous background factors and reading habits. Previous research indicates that dyslexia may worsen aggressive behaviour tendencies, and offenders with dyslexia are reported to be more violent than offenders without dyslexia. Violent crimes are strongly predicted by psychopathy, and therefore Study II focused on the relationship between phonological processing skills and psychopathy in order to clarify whether patients with dyslexia are characterized by psychopathy and therefore act more aggressively than those without dyslexia. However, the results from Study II showed that the patients’ reading speed, word decoding, and phonological processing skills were not significantly related to the total score of psychopathy, but significantly related to affective and interpersonal traits of psychopathy. In Study III, the focus was on aggression and risk of future violence in patients with and without dyslexia. The results revealed that the patients with dyslexia self-reported more anger and hostility compared to the patients without dyslexia. There was only a marginally significant tendency for the patients with dyslexia to have higher risk of future violence compared to those without dyslexia. However, poor phonological processing skills were a significant predictor of anger, which in turn predicted risk of future violence. Overall, the results showed that reading and writing problems are prevalent in forensic patients and that dyslexia does not have a straightforward relationship with future violence. The risk factors for criminality in patients with dyslexia are probably cumulative, and found in biological factors, individual abilities and personality, family, peers, school, community, and society.