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【medical-news】智商低的孩子容易发生精神疾病
Caroline Cassels
January 14, 2009 — Lower childhood IQ appears to predict the development of several common psychiatric disorders in adulthood, a finding that researchers say further validates the cognitive-reserve hypothesis.
A longitudinal prospective study by investigators from the Harvard School of Public Health, in Boston, Massachusetts, showed that for each standard-deviation increase in childhood IQ, participants had a 42% reduction in the odds of a lifetime schizophrenia diagnosis, a 23% reduction in the odds of an adult depression diagnosis, and a 26% reduction in the odds of an adult anxiety-disorder diagnosis.
The researchers, led by Karestan C. Koenen, PhD, also found lower childhood IQ was associated with greater comorbidity and persistence of depression, with a trend toward persistence of generalized anxiety disorder that neared significance.
"Our findings are consistent with the theory that lower cognitive reserve, as operationalized by childhood IQ, is a risk factor for major depression, and certain anxiety disorders, with greater comorbidity and persistence of disorder," the authors write.
The study is published in the January issue of the American Journal of Psychiatry.
First Study of its Kind
The cognitive-reserve hypothesis proposes that individuals with increased brain volume and enhanced cognitive ability are better able to buffer the effects of neuropathology.
Previous research has demonstrated that IQ as a marker of cognitive reserve is inversely related to risk for total psychiatric illness. However, the authors point out that, with the exception of schizophrenia research, few studies have investigated the potential link between IQ in early life and the risk for other specific adult psychiatric illnesses.
"To our knowledge, this is the first report of the association between childhood IQ and the full range of adult anxiety disorders," the investigators write.
To test the cognitive-reserve model for psychiatric disorders, the researchers conducted a longitudinal prospective study of a cohort of 1037 individuals born in 1972 and 1973 in Dunedin, New Zealand, following them out to age 32 years.
The initial assessment was conducted at age 3 years and every 2 years to age 15 years, and then at ages 18, 21, 26, and 32 years, when 972 participants — 96% of living cohort members — were assessed. Each assessment involved an 8-hour day of interviews and tests.
Study subjects had their IQs assessed at ages 7, 9, and 11 years using the Weschler Intelligence Scale for Children–Revised (WISC-R), and participants were screened for mental-health disorders at ages 18, 21, 26, and 32 years using Diagnostic and Statistical Manual of Mental Disorders (DSM) criteria.
The primary outcomes included any mental-health diagnosis in the past year at age 32 years. Exceptions to the 12-month time frame were manic episode and schizophrenia spectrum disorder.
Mania Linked to Higher, Not Lower, IQ
The finding that lower childhood IQ was linked to an increased risk for schizophrenia spectrum disorder, adult depression and adult anxiety remained significant after adjustment. However, schizophrenia spectrum disorder became marginal with the addition of statistical controls for confounders.
For specific anxiety disorders, the researchers found that individuals with higher childhood IQ had a 29% reduction in having generalized anxiety disorder and a 40% reduction in the odds of social phobia.
Higher IQ also appeared to reduce the risk for posttraumatic stress disorder and agoraphobia, although due to the small numbers of subjects with these conditions, this did not reach statistical significance.
Lower IQ was not linked to adult substance-dependence disorders. In contrast, the study showed higher, not lower, childhood IQ was significantly associated with mania, although only 8 subjects had this diagnosis.
"This finding for mania warrants replication, because it is counter to the cognitive-reserve hypothesis, and thus it may have resulted from chance. Also, this finding is relevant to the debate about whether schizophrenia and mania are etiologically distinct," the authors write.
Given that the study showed lower childhood IQ predicted greater psychiatric comorbidity, Koenen and colleagues suggest it may be that many individuals who seek mental-health treatment may also have lower cognitive ability, which could hamper their ability to access services or understand and adhere to treatment protocols.
"Such individuals," they write, "may benefit from interventions aimed at improving mental-health literacy. Cognitive ability may therefore be important to consider in prevention and in treatment planning."
The authors report no conflicts of interest.
Am J Psychiatry 2009;166:50-57. Abstract
http://www.medscape.com/viewarticle/586820
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作者:admin@医学,生命科学 2011-07-14 17:12
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