Reduced fronto-temporal connectivity is associated with frontal gray matter density reduction and neuropsychological deficit in schizophrenia

Frontal white matter integrity as an endophenotype for schizophrenia: diffusion tensor imaging in monozygotic twins and patients' nonpsychotic relatives

Diffusion tensor imaging (DTI) provides anatomical connectivity information by examining the directional organization of white matter microstructure. Anatomical connectivity and its abnormalities may be heritable traits associated with schizophrenia. To further examine this hypothesis, two studies were conducted to compare anatomical connectivity between (a) monozygotic (MZ) twin pairs and random pairings among twins and (b) first-degree relatives of schizophrenia patients and a healthy control group. Analyses focused on frontal regions of the brain following previous findings of anatomical connectivity abnormalities associated with schizophrenia. For Study 1, eighteen MZ twin pairs (11 female pairs, age: M = 25.44, SD = 5.69) were recruited. For Study 2, twenty-two first-degree relatives of schizophrenia patients (14 females, age: M = 48.50, SD = 8.22), and 30 healthy controls (12 females, age: M = 43.83, SD = 11.39) were recruited. Fractional anisotropy (FA), a white matter directional organization metric, was measured with DTI. In Study 1, FA values were more strongly correlated between MZ twin pairs than between randomly generated pairs in genu of corpus callosum, anterior cingulum and forceps minor. In Study 2, relatives of schizophrenia patients showed reduced FA values in medial frontal white matter (p < 0.05, corrected). The present study suggested that anatomical connectivity in medial prefrontal cortex appeared significantly heritable within MZ twin pairs, an important criterion in the development of an endophenotype. In addition, altered medial frontal white matter integrity found in non-affected relatives of schizophrenia patients seems to suggest that reduced white matter integrity in medial frontal regions of the brain might be associated with the genetic liability to schizophrenia.

Neighborhood differences in psychoses: prevalence of psychotic disorders in two socially-differentiated metropolitan areas of Barcelona

INTRODUCTION

The prevalence of schizophrenia and other psychoses can vary between close geographic locations and can be biased by the use of epidemiological designs. With data derived from a public mental health centre with close relations to primary care teams we have compared the distribution of psychotic disorders in two neighborhoods in Barcelona with marked psycho-social differences.

METHODS

Using a computerized database from Barcelona's National Health Service covering 5 basic health-care areas with a total population of 103,615 inhabitants, we have accessed case records showing any psycho-pathology between the years of 1982 and 2000.

RESULTS

From the case records of 21,536 registered patients showing any psycho-pathology, and using strict diagnostic, clinical and assistance criteria, we found that there were 476 patients diagnosed as "schizophrenic" and 362 that were "affected by other psychoses." Despite being evaluated by the same mental health personal, the same research team using identical criteria and over the same period of time (thus precluding operator and selection bias) the prevalence of these disorders was twice as high in La Mina (a district with a marked accumulation of psycho-social risk-factors) as compared to the neighboring district of La Verneda.

CONCLUSIONS

When assessing prevalence of psychoses, it is necessary to consider the impact of social and psycho-social factors, even in neighboring communities.