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Biomedical subjects

E F Torrey

Publications and source records attributed to E F Torrey.

At least 19 recordsLinked to original sources
PubMed1992

Regional cerebral blood flow in monozygotic twins discordant and concordant for schizophrenia.

We addressed several questions regarding hypofunction of the prefrontal cortex ("hypofrontality") in schizophrenia by measuring regional cerebral blood flow during three different cognitive conditions in monozygotic twins who were discordant or concordant for schizophrenia or who were both normal. These questions included the prevalence of hypofrontality, the importance of genetic predisposition, and the role of long-term neuroleptic treatment. Significant differences between affected and unaffected discordant twins were found only during a task linked to the prefrontal cortex, the Wisconsin Card Sorting Test. During this condition, all of the twins with schizophrenia were hypofrontal compared with their unaffected co-twins, suggesting that, if appropriate cognitive conditions and control groups are used, hypofrontality can be demonstrated in the majority of, if not all, patients with schizophrenia. When unaffected co-twins of patients with schizophrenia were compared with twins who were both normal, no differences were observed, suggesting that nongenetic factors are important in the cause of the prefrontal physiologic deficit that appears to characterize schizophrenia. When concordant twins with a high- vs a low-dose lifetime history of neuroleptic treatment were compared, the twin receiving the higher dose was more hyperfrontal in six of eight pairs, suggesting that long-term neuroleptic treatment does not play a major role in hypofrontality.

Adult↗
PubMed1992

Dichotic listening in monozygotic twins discordant and concordant for schizophrenia.

Emotional and neutral word versions of the fused rhymed words dichotic listening test were administered to members of 18 pairs of monozygotic twins discordant for schizophrenia, 7 pairs concordant for schizophrenia, and 7 pairs of normal twins. In the discordant group, affected twins had smaller right ear advantages than did their unaffected cotwins for neutral words. The difference was completely attenuated with the presentation of emotional words or in less powerful between-group comparisons that included twins concordant for schizophrenia and normal twins. It is unlikely that this finding reflects an abnormality in the lateralized representation of language, both because we did not find a correlation between handedness scores and dichotic listening scores and because emotional stimuli normalized results. The finding may reflect abnormalities in the allocation of attention for priming language centers in the left hemisphere. 'At risk' subjects, i.e., the unaffected members of the discordant pairs, did not differ significantly from normal monozygotic twins on measures of dichotic listening.

Adult↗
PubMed1992

Second-trimester markers of fetal size in schizophrenia: a study of monozygotic twins.

OBJECTIVE: Since the second prenatal trimester is the critical period of massive neural cell migration to the cortex, and fingertip dermal cells migrate to form ridges during this same period, the authors sought to determine whether there are differences in fingertip ridge count in pairs of monozygotic twins discordant for schizophrenia, possibly indicating that a prenatal anatomical insult affected the twins differently. METHOD: The fingertip dermal ridges of 30 pairs of monozygotic twins (23 pairs in which the twins were discordant for schizophrenia and seven pairs in which both twins were normal) were counted by two persons trained in anthropometric research. Intrapair differences in the counts were then measured, and the differences among the pairs of normal twins were compared with the differences among the pairs discordant for schizophrenia. RESULTS: The twins discordant for schizophrenia had significantly greater absolute intrapair differences in total finger ridge count and significantly greater percent intrapair differences than the normal twins; i.e., their fingerprints were significantly less "twin-like." CONCLUSIONS: The study suggests that various second-trimester prenatal disturbances in the epigenesis of one twin in a pair discordant for schizophrenia may be related to the fact that only one of the twins expresses his or her genetic predisposition toward schizophrenia. This is consistent with a "two-strike" etiology of schizophrenia: a genetic diathesis plus a second-trimester environmental stressor.

Adult↗
PubMed1979

Lateral cerebral ventricular enlargement in chronic schizophrenia.

To investigate if cerebral ventricular enlargement is associated with chronic schizophrenia, computerized tomography scans from 73 psychiatric patients were compared with 56 asymptomatic volunteers all less than 50 years old. Ventricular size was significantly greater in the subgroup of 58 chronic schizophrenic patients than in the controls. Of the chronic schizophrenic patients, 40% were outside the control range; 53% exceeded 2 SDs of the control mean. Neither duration of illness nor length of hospitalization correlated with ventricular size. The 44 chronic schizophrenic patients who had never been treated with electroshock therapy (EST) had larger ventricles than controls. A group of seven nonchronic schizophrenic patients also had enlarged ventricles; the eight patients who were either schizoaffective or nonschizophrenic did not differ from controls. This study shows that lateral cerebral ventricular enlargement is associated with chronic schizophrenia; it suggests that this is not a result of treatment.

Adult↗
PubMed1979

Structural abnormalities in the cerebral cortex of chronic schizophrenic patients.

Enlarged cerebral ventricles in chronic schizophrenic patients suggest a process of mild cerebral atrophy occurs in some. To see if this process involves the cerebral cortex, the widths of the Sylvian fissure, the interhemispheric fissure, and three cortical sulci were measured blindly on computerized tomography (CT) scans of 75 chronic psychiatric patients and 62 asymptomatic volunteers, all less than 50 years of age. A total of 19 of the 60 patients with chronic schizophrenia had at least one abnormality. All 15 patients with other diagnoses were within the control range. Comparing those chronic schizophrenic patients with abnormalities to those without them, there were no significant differences in age, length of illness or treatment, and length of hospitalization. From this and ventricular size data, two thirds of the chronic schizophrenics had some cerebral structural abnormality. Ventricular enlargement did not correlate significantly with cortical abnormalities. Therefore, more than one etiology may account for the structural abnormalities found in chronic schizophrenic patients.

Adult↗
PubMed1979

Hypertension among Aleuts.

Surveys of Aleuts on St. Paul Island, Alaska, in 1966 and 1976 found a prevalence of hypertension as high as any reported in the United States. The rate remained high over the 10-year period. Preliminary data from other Aleut villages on the Aleutian Chain indicate that a high prevalence of hypertension may be widespread in this region. Etiologically genetic factors, obesity, and a high salt intake are all present. In addition, an exceedingly high level of cadmium content was found in seal livers, a dietary staple. Isolated locations such as St. Paul provide natural laboratories for possibly elucidating the complex etiology of this disease.

Adolescent↗
PubMed1979

A shifting seasonality of schizophrenic births.

In view of recent findings in Japan, and in England and Wales, data on schizophrenic births in the United States were reexamined to see if seasonal shifts had occurred. In Missouri a progressive shift from February to April and May was noted between 1921 and 1930 and between 1941 and 1950. In five New England states there was no shift over the same period. Data were then obtained to compare the Missouri shift with two hypotheses previously put forward to explain schizophrenic birth seasonality: (1) that it is related to the seasonality of general births, and (2) that it is related to seasonal temperature variation. Neither hypothesis was supported by the data.

Adult↗
PubMed1979

Assessment of clinical status of schizophrenic patients by the WAIS comprehension subtest.

A previous study indicated that the Comprehension subtest of the Wechsler Adult Intelligence Scale (WAIS) might be a sensitive instrument for evaluating mental status in schizophrenic patients. To test this hypothesis, 3 groups of subjects were given the WAIS Comprehension subtest repeatedly at brief intervals. The results indicate that for a given individual (normal control or stable chronic schizophrenic), scores do not increase even with 4 consecutive weeks of testing. In contrast, a group of schizophrenic patients tested shortly after readmission and again after being established on neuroleptic medication showed a marked improvement in scores which, somewhat surprisingly, were not correlated with changes in global ratings of disordered thinking by the treating psychiatrist. This standardized test may offer a convenient objective technique for quantifying some aspects of thinking in schizophrenic patients.

Adolescent↗
PubMed1977

Seasonality of schizophrenic births in the United States.

The birth months of persons later diagnosed as schizophrenic were studied. Data were collected from 19 states on 53,584 schizophrenics born between 1920 and 1955. The controls were the general births in the same states for the same years. A highly significant peak in schizophrenic births was found from December to May, most marked in March and April. The seasonality was stronger in New England and the Midwest than in the South. Previous studies of schizophrenic births are also reviewed. The cumulative evidence would appear to establish more firmly a winter and spring seasonality of schizophrenic births in northern Europe and the eastern United States. Selection of patients, nutritional factors, environmental factors, genetic factors, and infectious agents are discussed as possible etiological explanations.

Adult↗