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Twin studies of schizophrenia supply a key part of the rationale supporting the many ongoing searches for susceptibility loci. Sullivan et alArticle present a meta-analysis of 12 twin studies for schizophrenia. The meta-analytic estimate showed high heritability. Surprisingly, there was consistent evidence across these studies for common environmental influences on liability to schizophrenia.
Patients with schizophrenia exhibit olfactory impairments, but it is unclear whether these represent a specific abnormality or reflect more diffuse cognitive impairments. Using a histologically guided magnetic resonance imaging analysis, Turetsky et alArticle observed reduced volumes of the entorhinal and perirhinal cortices, which receive direct afferent inputs from the olfactory bulb. The adjacent temporal pole, which receives no bulbar afferents, had normal volume. Reductions in the perirhinal cortex were selectively associated with decreased ability to detect odors but not with verbal or spatial memory deficits.
Blumberg et alArticle measured amygdala and hippocampal volumes in a magnetic resonance imaging morphological investigation of adolescents and adults with bipolar disorder and a healthy comparison group. Significant volume reductions in amygdala were observed in bipolar disorder for adults as well as for adolescents. These findings suggest that amygdala volume deficits are an early feature of bipolar disorder that are present by adolescence and persist into adulthood.
In a population-based cohort in Denmark, Mortensen et alArticle studied risk factors for bipolar affective disorder. Risk was associated with a family history of bipolar affective disorder as well as other psychiatric disorders. Early parental, especially maternal, loss, was also a risk factor, whereas other factors such as urbanicity associated with schizophrenia were not associated with bipolar affective disorder, supporting the notion that the 2 disorders may be at least partially separate etiological entities.
Tohen et alArticle compared olanzapine and haloperidol in the treatment of acute manic episodes. For all patients, rates of remission were comparable between the treatment groups, but significantly higher for olanzapine-treated patients in those without psychotic features. Haloperidol-treated patients had higher rates of switching to depression and worsening of extrapyramidal symptoms, whereas olanzapine-treated patients experienced greater weight gain.
It is commonly accepted that there is a delay of a number of weeks between the initiation of antipsychotic treatment and the onset of antipsychotic effect. Agid et alArticle undertook a meta-analysis of 42 controlled trials and found that there was no delay in onset. In fact, the greatest rate of improvement was found in the first 2 weeks of treatment. This has important implications for the study of neurobiological mechanisms that underlie antipsychotic response.
Olfson et alArticle examined outpatient treatment of depression in children and adolescents using the 1996-1999 Medical Expenditure Panel Survey. The estimated annual rate of treatment was 0.93 per 100 youth aged 6 to 18 years. Among those who received treatment, 79% received psychotherapy and 57% received antidepressants. The comparatively low rate of treatment suggests widespread gaps in service access. At the same time, the frequent use of antidepressants indicates that these medications have become a mainstay in the treatment of depressed youth.
Luby et alArticle investigated the cortisol reactivity in depressed preschoolers, using an experimental design that employed structured psychosocial stressors. The findings demonstrated a unique pattern of cortisol reactivity among depressed preschoolers relative to psychiatric and no disorder comparison groups and suggest continuity of hypothalamic-pituitary-adrenal axis alterations in major depressive disorder across the lifespan.
Rhee et alArticle conducted a study of initiation, use, and problem use of tobacco, alcohol, and illicit drugs in adolescent monozygotic twins, dizygotic twins, biological siblings, and adopted siblings. Genetic influences were moderate to substantial (with the exception of alcohol use and any drug use) and the influence of the shared environment was modest or moderate for substance initiation, use, and problem use. The results are comparable to those found in twin studies of adults.
Jacob et alArticle examined the relative importance of genetic and environmental influences on alcohol dependence with the offspring of twins design. Results supported the hypothesis that a low-risk family environment (ie, the absence of parental alcoholism) can moderate the impact of high genetic risk in regard to offspring risk for alcohol use disorder.
This Month in Archives of General Psychiatry. Arch Gen Psychiatry. 2003;60(12):1181. doi:10.1001/archpsyc.60.12.1181