The
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Conduct Disorder and Callous–Unemotional Traits in Youth To the Editor: Blair et al. (Dec. 4 issue)1 are thorough and insightful in their review of conduct disorder and related entities, except that there is no reference to sex, sex ratios, or male sex. Yet for childhood-onset conduct disorder that persists throughout life, there is consensus that there is a massive male predominance, by a factor of 10 to 15, whereas for conduct disorder generally, the ratio is still between 2:1 and 4:1.2 Mounting evidence suggests that prenatal androgenization affects the brains of human male fetuses as it does the brains of many other mammals, resulting in a partially gendered brain.3 The hypothalamus and amygdala, which Blair et al. identify as participating in hypothesized conduct disorder–related neural circuits, are affected by this organizational effect of androgens, and activational effects of pubertal and postpubertal androgens further influence their function. Violence, which is overwhelmingly used by young men, cannot be understood in terms of brain function, prevention, or treatment without reference to and investigation of sex differences and male-predominant neuroendocrine effects.
The Authors Reply: Konner correctly highlights the finding that aggression and conduct disorder occur more commonly in males than in females. We did not discuss this finding because the causes of such sex differences remain unclear. Serious behavior problems do not develop in most boys; hence, on its own, the biology associated with being male clearly does not cause conduct disorder. Most sex differences in behavior reflect complex interactions between genetic and environmental factors, and this is also likely to be true for conduct disorder and aggression. Our article focused on associations between dysfunction in specific neurocognitive mechanisms and conduct disorder. Data suggest the existence of sex differences in these mechanisms and in measures of other brain functions, even if their origins remain controversial.1 Although studies have examined sex differences in the neurocognitive mechanisms that we considered, findings remain inconsistent. Future work may confirm some of these early findings and clarify how being male confers a risk of conduct disorder in the context of neurocognitive development.
Melvin Konner, M.D., Ph.D.
R. James R. Blair, Ph.D. Ellen Leibenluft, M.D. Daniel S. Pine, M.D.
Emory University
Atlanta, GA [email protected] No potential conflict of interest relevant to this letter was reported. 1. Blair RJ, Leibenluft E, Pine DS. Conduct disorder and callous–
unemotional traits in youth. N Engl J Med 2014;371:2207-16. 2. Eme RF. Sex differences in child-onset, life-course-persistent conduct disorder: a review of biological influences. Clin Psychol Rev 2007;27:607-27. 3. Bao AM, Swaab DF. Sexual differentiation of the human brain: relation to gender identity, sexual orientation and neuropsychiatric disorders. Front Neuroendocrinol 2011;32:214-26.
National Institute of Mental Health
Bethesda, MD [email protected] Since publication of their article, the authors report no further potential conflict of interest. 1. Cahill L. Equal ≠ the same: sex differences in the human
brain. Cerebrum 2014;2014:5.
DOI: 10.1056/NEJMc1415936
DOI: 10.1056/NEJMc1415936
Sensor Technology in Assessments of Clinical Skill To the Editor: Clinical-skills assessments pro- ods has introduced a wide variety of options for vide motivation and direction for learning.1,2 clinical-performance assessment.3,4 To explore Adoption of simulation-based education meth- the potential value added by integrating sensor
784
n engl j med 372;8 nejm.org february 19, 2015
The New England Journal of Medicine Downloaded from nejm.org at NYU WASHINGTON SQUARE CAMPUS on June 23, 2015. For personal use only. No other uses without permission. Copyright © 2015 Massachusetts Medical Society. All rights reserved.
n e w e ng l a n d j o u r na l
of
m e dic i n e
Conduct Disorder and Callous–Unemotional Traits in Youth To the Editor: Blair et al. (Dec. 4 issue)1 are thorough and insightful in their review of conduct disorder and related entities, except that there is no reference to sex, sex ratios, or male sex. Yet for childhood-onset conduct disorder that persists throughout life, there is consensus that there is a massive male predominance, by a factor of 10 to 15, whereas for conduct disorder generally, the ratio is still between 2:1 and 4:1.2 Mounting evidence suggests that prenatal androgenization affects the brains of human male fetuses as it does the brains of many other mammals, resulting in a partially gendered brain.3 The hypothalamus and amygdala, which Blair et al. identify as participating in hypothesized conduct disorder–related neural circuits, are affected by this organizational effect of androgens, and activational effects of pubertal and postpubertal androgens further influence their function. Violence, which is overwhelmingly used by young men, cannot be understood in terms of brain function, prevention, or treatment without reference to and investigation of sex differences and male-predominant neuroendocrine effects.
The Authors Reply: Konner correctly highlights the finding that aggression and conduct disorder occur more commonly in males than in females. We did not discuss this finding because the causes of such sex differences remain unclear. Serious behavior problems do not develop in most boys; hence, on its own, the biology associated with being male clearly does not cause conduct disorder. Most sex differences in behavior reflect complex interactions between genetic and environmental factors, and this is also likely to be true for conduct disorder and aggression. Our article focused on associations between dysfunction in specific neurocognitive mechanisms and conduct disorder. Data suggest the existence of sex differences in these mechanisms and in measures of other brain functions, even if their origins remain controversial.1 Although studies have examined sex differences in the neurocognitive mechanisms that we considered, findings remain inconsistent. Future work may confirm some of these early findings and clarify how being male confers a risk of conduct disorder in the context of neurocognitive development.
Melvin Konner, M.D., Ph.D.
R. James R. Blair, Ph.D. Ellen Leibenluft, M.D. Daniel S. Pine, M.D.
Emory University
Atlanta, GA [email protected] No potential conflict of interest relevant to this letter was reported. 1. Blair RJ, Leibenluft E, Pine DS. Conduct disorder and callous–
unemotional traits in youth. N Engl J Med 2014;371:2207-16. 2. Eme RF. Sex differences in child-onset, life-course-persistent conduct disorder: a review of biological influences. Clin Psychol Rev 2007;27:607-27. 3. Bao AM, Swaab DF. Sexual differentiation of the human brain: relation to gender identity, sexual orientation and neuropsychiatric disorders. Front Neuroendocrinol 2011;32:214-26.
National Institute of Mental Health
Bethesda, MD [email protected] Since publication of their article, the authors report no further potential conflict of interest. 1. Cahill L. Equal ≠ the same: sex differences in the human
brain. Cerebrum 2014;2014:5.
DOI: 10.1056/NEJMc1415936
DOI: 10.1056/NEJMc1415936
Sensor Technology in Assessments of Clinical Skill To the Editor: Clinical-skills assessments pro- ods has introduced a wide variety of options for vide motivation and direction for learning.1,2 clinical-performance assessment.3,4 To explore Adoption of simulation-based education meth- the potential value added by integrating sensor
784
n engl j med 372;8 nejm.org february 19, 2015
The New England Journal of Medicine Downloaded from nejm.org at NYU WASHINGTON SQUARE CAMPUS on June 23, 2015. For personal use only. No other uses without permission. Copyright © 2015 Massachusetts Medical Society. All rights reserved.
