Istvan is a Clinical and Forensic Psychologist and holds a Bachelor of Psychology (Honours) degree, a Master of Forensic Psychology degree and a Master of Clinical Psychology degree. Istvan has 9 years clinical experience both in the private and the public sector, working for Northside West and Northside Cremorne private psychiatric clinics, the University of Sydney and for various community organisations. As part of these positions Istvan carried out neuropsychological assessments with psychiatric inpatients, designed and supervised treatment programs and provided individual therapy.

Istvan is also highly experienced in conducting psychological assessments with children and adolescents. He carried out mass testing in NSW public and private schools to determine the nature of worry in school children and assisted a large scale research study of disadvantaged youth in NSW. The research paper is available here. As part of his private practice Istvan conducts psychological assessments with children, provides medico-leagal reports to assist Workers Compensation and CTP insurance claims, performs diagnostic assessments for major injuries and works as a treating psychologist for various psychological disorders.