A PRELIMINARY-REPORT OF A STRONG GENETIC COMPONENT FOR THOUGHT-DISORDER IN NORMALS - A TWIN STUDY

Several authors have investigated the presence of thought disorder in psychiatric patients using different reliable methods. Under the hypot hesis of a genetic predisposition to thought disorder, the degree and quality of thought disorder have also been studied in populations at a high risk for psychosis, in particular for schizophrenia. As a result , an increasing incidence of thought disorder was detected in relative s of schizophrenics. To account for the thought disorder also found in normal subjects, researchers propose that thought disorder exists in normal subjects on a continuum with schizophrenic patients. In the fol lowing report, we evaluated the inherited component of thought disorde r in normal subjects, using a sample of 25 normal twin pairs, 16 monoz ygotic and 9 dizygotic twin pairs. We applied the Thought Disorder Ind ex (TDI) to assess disordered thinking, genetic estimates were made wi th classical methods, controlling for environmental sources of variabi lity where possible. Our findings suggest a strong additive genetic co mponent for the global TDI rating variable, with a heritability estima te approaching 80-90%. New approaches in neuropsychology and neuropsyc hiatry based on genetic methodologies should further define the cerebr al physiology responsible for disordered thinking.