ABSTRACT
Life history study of monozygotic (MZ) twins discordant for schizophrenia led to the 1967 hypothesis that phenotypic schizophrenia was an expression of genotypic vulnerability interacting with prenatal and/or perinatal environmental experience. This report is a selected review of partial answers to five questions facing research efforts that have attempted to clarify the interactive gene-environment model of schizophrenia. Follow-up study of the offspring of MZ twins with a diagnosis of schizophrenia and their MZ co-twins without schizophrenia demonstrated equal rates of schizophrenia; hence, each group of offspring carried equal genetic vulnerability for schizophrenia. Magnetic resonance imaging study of MZ discordant twins found that phenotypic schizophrenia was characterized by brain ventricular enlargement and hippocampal reduction in 87-93% of the schizophrenic twins, when compared with their nonschizophrenic co-twins. A longitudinal study of teenage children at differential risk for schizophrenia showed that brain ventricular enlargement in adulthood correlated significantly and positively with genetic risk for schizophrenia and number of perinatal complications, and negatively with birth weight. Significantly greater dysmorphological hand skin signs among schizophrenic MZ twins when compared with their nonschizophrenic co-twins have suggested an in utero second trimester fetal developmental abnormality for the schizophrenic subjects. Simultaneous neuroanatomic, neurophysiological, and neurocognitive evaluation of MZ twin pairs discordant for schizophrenia demonstrated decreased prefrontal physiological cerebral blood flow activation during Wisconsin Card Sorting Test for affected twins correlated with decreased hippocampal volume determined by magnetic resonance imaging. These neurocognitive studies have suggested that schizophrenia involves neocortical-limbic pathology and dysfunction implicated in performance of cognitive tasks requiring working memory.(ABSTRACT TRUNCATED AT 250 WORDS)
Subject(s)
Diseases in Twins/genetics , Family , Schizophrenia/genetics , Adolescent , Adult , Brain/abnormalities , Brain/anatomy & histology , Brain/pathology , Cerebral Ventricles/anatomy & histology , Cerebral Ventricles/pathology , Cerebral Ventriculography , Child , Diseases in Twins/diagnosis , Female , Genotype , Hippocampus/anatomy & histology , Hippocampus/pathology , Humans , Infant, Newborn , Magnetic Resonance Imaging , Male , Models, Genetic , Phenotype , Pregnancy , Pregnancy Complications/diagnosis , Schizophrenia/etiology , Schizophrenia/pathology , Twins, MonozygoticABSTRACT
Survey data from the United States indicate that tobacco use is associated with the initiation of use of other addicting substances, and that increasing levels of tobacco use are associated with increasing levels of use of other psychoactive substances. Furthermore, factors affecting initiation, abstinence, and relapse to the use of tobacco, alcohol, and opioids are similar in nature. In addition, there are similarities in the addictive process underlying the use of these substances. Taken together, these data suggest that tobacco use is involved, possibly more than by simple association, in the use of other substances containing psychoactive chemicals. In the present paper we discuss the involvement of tobacco in the use of alcohol, opioids, cocaine, and other substances, as well as some of the implications of these observations for researchers and clinicians. One such implication is that it may be possible to use tobacco and nicotine as models for phenomena of interest to other substance use researchers. For example, drug abuse treatment and prevention strategies could be explored using tobacco use as a target behavior, and biological phenomena such as the development of tolerance and physical dependence may be more readily studied with nicotine than with many other drugs. Certain pharmacologic differences across substances are also discussed in light of their implications for development of treatment and drug control policies.
Subject(s)
Alcoholism/psychology , Illicit Drugs , Smoking/adverse effects , Substance-Related Disorders/psychology , Adolescent , Adult , Humans , Risk Factors , Smoking/psychologyABSTRACT
Addictive disorders now cause more than one fourth of all deaths in the United States--more than a half million deaths in 1982. But this essential fact is obscured in the nation's vital records and statistics by the general practice of certifying addictive disease deaths to their innumerable anatomic manifestations. However, this situation need not continue indefinitely. Physicians have both an opportunity and a responsibility to state their knowledge of the underlying causes of deaths occurring under their care, and the diagnostic category "Tobacco Use Disorder/Tobacco Dependence," listed in the ninth revision of the International Classification of Diseases is available for their use. By routinely ascertaining the lifetime smoking experience of each patient and stating on each death certificate the role of tobacco, physicians can contribute substantially to improvement of vital statistics, epidemiology, and public health.
Subject(s)
Death Certificates , Tobacco Use Disorder/mortality , Humans , Medical Records , Smoking , Tobacco Use Disorder/physiopathology , United StatesABSTRACT
Handedness in the NIMH monozygotic (MZ) schizophrenic twins was examined and compared to the report of Boklage. Both our findings and Boklage's suggest the existence of a subgroup of schizophrenics characterized by abnormal lateralization and a milder form of schizophrenia. However, unlike Boklage, we hypothesize that this subgroup of schizophrenics is not restricted to MZ twins.
Subject(s)
Diseases in Twins , Functional Laterality , Schizophrenia/genetics , Schizophrenic Psychology , Birth Order , Birth Weight , Female , Humans , Pregnancy , Twins, MonozygoticSubject(s)
Parents , Perception , Personality Development , Twins , Attitude , Child, Preschool , Emotions , Father-Child Relations , Female , Humans , Individuality , Infant , Infant, Newborn , Male , Mother-Child Relations , Pregnancy , Reinforcement, Psychology , Role , Twins, MonozygoticSubject(s)
Coronary Disease/etiology , Hypercholesterolemia/complications , Personality , Ethnicity , Female , Humans , Interview, Psychological , Lipoproteins, LDL/blood , Male , Middle Aged , Risk , Triglycerides/bloodABSTRACT
Blood typing is the most reliable method for assigning zygosity to twinships in psychological research. Cost, ethical considerations, and practical difficulties in obtaining blood specimens from a large group of children suggested the need for a questionnaire method used with young children and completed by parents. One was designed to assess zygosity based on the extent to which the children were rated as looking alike and being confused by family and strangers. Validity was determined with a sample of twins whose zygosity was demonstrated by blood typing. To determine test-retest reliability, and to explore parental beliefs about zygosity, mothers of same-sex twinships completed the questionnaire on two separate occasions, showing very high agreement. The major difference in parental perceptions of monozygotic and dizygotic twinships is convenient for epidemiological research. This difference, however, questions the assumption, made in estimates of heritability using twin data, that both twinships have identical environmental experiences.
Subject(s)
Research Design , Twins , Blood Group Antigens , Female , Humans , Pregnancy , Surveys and Questionnaires , Twins, Dizygotic , Twins, MonozygoticSubject(s)
Affective Symptoms/genetics , Bipolar Disorder/genetics , Diseases in Twins , Bipolar Disorder/diagnosis , Bipolar Disorder/epidemiology , Computers , Depression/diagnosis , Depression/epidemiology , Depression/genetics , Diagnosis, Differential , Humans , Medical Records , Military Psychiatry , Phenotype , Registries , Research Design , United States , United States Department of Veterans AffairsSubject(s)
Methionine/pharmacology , Schizophrenia/metabolism , Schizophrenic Psychology , Adult , Brain Chemistry/drug effects , Chronic Disease , Delusions/chemically induced , Emotions/drug effects , Female , Hallucinations/chemically induced , Humans , Male , Methionine/metabolism , Middle Aged , Models, Biological , Monoamine Oxidase Inhibitors/pharmacology , Perception/drug effects , Psychoses, Substance-Induced/etiology , Research Design , Serotonin/metabolismSubject(s)
Diseases in Twins , Schizophrenia/genetics , Adolescent , Adult , Age Factors , Female , Follow-Up Studies , Hospitalization , Humans , Interview, Psychological , Male , Middle Aged , Schizophrenia/diagnosis , Schizophrenic Psychology , United States , United States Substance Abuse and Mental Health Services AdministrationSubject(s)
International Cooperation , National Institute of Mental Health (U.S.) , Research , Schizophrenia , United States Substance Abuse and Mental Health Services Administration , Epidemiologic Methods , Humans , Remission, Spontaneous , Research Design , Research Support as Topic , Schizophrenia/blood , Schizophrenia/genetics , Schizophrenia/microbiology , Social Adjustment , USSR , United States , Virus Diseases/complications , World Health OrganizationSubject(s)
Genotype , Twins , Blood Group Antigens , Body Height , Body Weight , Child , Face , Family , Female , Fertilization , Genetic Variation , Genetics, Behavioral , Hair , Humans , Iris , Male , Ovum , Phenotype , Pigmentation , Pregnancy , Surveys and QuestionnairesABSTRACT
Monoamine oxidase activity in blood platelets was measured, with [(14)C]tryptamine as substrate, in 13 monozygotic twin pairs discordant for schizophrenia and in 23 normal volunteers. The monoamine oxidase activity of both schizophrenic and nonschizophrenic co-twins was significantly lower than it was for the normals, and it was highly correlated between twins. In addition, there was a significant inverse correlation between a measure of the degree of the schizophrenic disorder and the monoamine oxidase activity. These data suggest, but do not prove, that reduced platelet monoamine oxidase activity may provide a genetic marker for vulnerability to schizophrenia.
