作者：Caroline Cassels
出處：WebMD醫學新聞
January 14, 2009 — 研究者們表示，低IQ兒童顯然可以預測成人時期發展出許多常見的精神異常，這項發現需要之後進一步確認認知保留假說。
一項由麻州波士頓哈佛大學公共衛生學院的研究者們進行的縱向前瞻性研究，結果顯示兒童IQ每增加一個標準差，受試者終生有精神分裂症診斷的勝算下降42%，有憂鬱症診斷的勝算下降23%，成人焦慮異常診斷的勝算下降26%。
這些研究者由Karestan C. Koenen博士領導，也發現了低IQ兒童與之後憂鬱症發病及持續有關，且有顯著持續廣泛性焦慮異常的趨勢。
作者寫到，我們的發現與低認知保留，以低IQ兒童來說，是重鬱症與特定機率異常的一個危險因子，且與這些疾病的發病與持續有關。
這項研究發表在1月號的美國精神醫學期刊。
【第一篇此類研究】
認知保留假說假設，腦部容積增加且認知能力增強的個體，比較能夠緩衝神經病理效應。
過去的研究顯示IQ是一個認知保留的指標，且與整體精神疾病風險成反比；然而，作者指出，除了精神分裂症研究之外，很少有研究針對兒童時期IQ與之後特定成人精神疾病風險之間的關係進行研究。
研究者寫到，據我們所知，這是第一篇有關兒童IQ與所有形式之成人焦慮異常關聯的報告。
為了檢視認知保留模式與精神異常的關係，研究者們進行了一項收納1,037位於1972到1973年在紐西蘭但尼丁出生個體的縱向前瞻性研究。
起始評估從3歲開始，之後每2年進行一次，直到15歲為止，接下來在18、21、26與32歲各進行一次評估，972位受試者，96%存活的成員接受了評估，每次的評估都需要8小時的訪談與檢查。
受試者在7、9與11歲時接受新版Weschler兒童智力分數（WISC-R）評估他們的IQ，接著受試者在18、21、26與32歲時接受精神異常診斷與統計手冊（DSM）診斷標準的篩檢。
主要的試驗終點為包括在32歲時，過去一年間有任何精神健康相關的診斷；在12個月時程的例外是躁鬱發作與精神分裂範圍異常。
【躁鬱與高IQ而不是低IQ有關】
低IQ與精神分裂範圍異常、成人憂鬱與焦慮有關的發現，在校正後仍然是顯著的。然而，精神分裂症範圍異常這項，在加入統計控制干擾因子後變得式微。
對特定焦慮異常來說，研究者們發現高成人IQ的個體，有廣泛性焦慮異常的勝算下降29%，而有社交恐懼症的勝算下降40%。
高IQ顯然會下降創傷後壓力症候群與廣場恐懼症的風險，罹患這些異常的病患數目很少，並未達到統計上顯著差異。
低IQ並未與成人物質濫用異常有關。相反的，這項研究結果顯示，高IQ顯著地與躁鬱症有關，而不是低IQ；雖然僅有8位受試者有這樣的診斷。
這項與躁鬱症有關的研究發現需要重複檢驗，因為這與認知保留假說相反，因此這可能是肇因於隨機誤差。作者寫到，再者，這項發現與有關於精神分裂症與躁鬱症病因學相異的爭議有關。
有鑑於這項研究顯示低兒童IQ可以預測更多的精神病併發疾病，Koenen與其同事表示，這可能是許多尋求精神健康治療的人們認知能力也較差的原因，這會阻礙他們接受醫療照護或是對治療計畫的依從性的能力。
他們寫到，這樣的人們，可能因為針對改善精神健康知識而受益，認知能力可能因此對預防與治療計畫來說是重要的。
作者們表示沒有利益衝突。
Lower Childhood IQ Increases Risk for Subsequent Psychiatric Disorders
By Caroline Cassels
Medscape Medical News
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.
[ 本帖最後由 goodcat1111 於 2009-2-18 00:00 編輯 ] |
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