Relative risk was estimated by using cutoff scores that were 1, 2, and 3 SDs below the mean of the normal comparison group in CPT both with and without distraction. Fifty percent of the patients, 24% of their siblings, and 18% of the normal comparison subjects scored 1 SD below the mean score of the comparison group

for the more difficult distraction version of the CPT. The patients with CPT scores 1 SD below the mean score of the comparison group had a total of 97 siblings. Compared with the comparison group, this subgroup of siblings had significantly lower CPT scores. Relative risk was also significantly higher for the siblings of patients whose scores were 1 SD (RR=2.1) and 2 SDs (RR=3.3) below the mean of Inhibitors,research,lifescience,medical comparison subjects. The authors concluded that poor performance on the CPT is familial, possibly genetic, and could increase the power of genetic studies

of schizophrenia. Although perturbations of executive functions seem to be the most consistently observed candidate intermediate phenotypes in schizophrenia, given the diversity of the human Inhibitors,research,lifescience,medical cognitive behavioral always find useful information repertoire, and the apparent complexity of the molecular genetics subserving this complex behavioral array, it is unreasonable to expect any family-based study to mirror a single set of cognitive or Carfilzomib FDA physiological deficits.35-45 Nonetheless, taken as a whole, the weight of neuropsychological studies Inhibitors,research,lifescience,medical robustly support assumptions that independent domains of cognitive function are heritable and are differentially linked to risk Inhibitors,research,lifescience,medical for schizophrenia. Neuroimaging Structural imaging Structural imaging protocols have long attracted attention in schizophrenia research, inasmuch as they are noninvasive and are a relatively easy means by which to collect large numbers of volunteers. The 1976 study of Johnstone and colleagues46 established a relationship Inhibitors,research,lifescience,medical between cerebral ventricular volume and cognitive impairment in schizophrenia. Using x-ray computerized tomography, Weinberger et al47 subsequently found increased ventricular

volume in 12 healthy siblings of patients with schizophrenia compared with well-matched healthy controls, and found that the affected GSK-3 siblings had larger ventricles than their unaffected sibs or healthy controls; a trend towards larger ventricles was also found in the unaffected siblings, suggesting a relationship to state and trait aspects. Reveley and colleagues48 studied ventricular size in healthy MZ and DZ twins compared with MZ twins discordant for schizophrenia. They reported that ventricular size was highly heritable in healthy MZ twins (h 2=0.98), moderately heritable in DZ twins (h 2=0.45), and highly heritable in MZ twins discordant for schizophrenia (h 2=0.87).The results of this study suggested a strong relationship between family history of psychosis and lateral ventriculomegaly, but the effect of shared environmental factors could not be excluded.