Personality and the X chromosome.

Personality and the X chromosome 

Abnormalities in sex chromosome number have been associated not only with anatomical, physiological and intellectual characteristics (SN:6/7/86, p. 358) but also with different personality traits. Psychologists now report a reassessment of some of those traits and an examination of how they arise during childhood and adolescence.

Women lacking a second X chromosome (XO) a condition known as Turner's syndrome, have been described as emotionally immature, stolid and highly tolerant of stress. Elizabeth McCauley of the University of Washington in Seattle says that in her clinical work she became concerned that there were more subtle behavioral concerns that were not being properly addressed. In a study of 30 XO adults she found markedly low self-esteem, both on a self-concept test and when the women were evaluated in an interview.

Next she examined 17 XO girls matched by a variety of factors to chromosomally normal, but short, girls. (Girls and women with Turner's syndrome tend to be very short.) McCauley reports that the XO girls were less socially adept and less self-confident. In addition, the XO children performed more poorly on a test in which they were asked whether videotaped facial expressions were intended to encourage or discourage the approach of an observer. McCauley suggests that this difficulty could contribute to the social problems. She speculates that both the spatial and face-interpreting skills may be related to the activity of the right brain hemisphere, which some scientists believe is suppressed in Turner's syndrome. She concludes, "The present findings suggest that short stature is not the reason for the social and emotional difficulties of the Turner syndrome patients."

Both men and women who have an extra X chromosome (XXY and XXX individuals) have been characterized as passive and shy. In his studies on XXY males, Charles Netley of the Hospital for Sick Children in Toronto suggests that this social withdrawal, as well as language difficulties, correlates with increased right hemisphere activity.

A study by Bruce G. Bender and Arthur Robinson of Denver's National Jewish Center for Immunology and Respiratory Medicine links childhood developmental disorders with later emotional and behavioral problems. Adolescents with sex chromosome abnormalities (SCA), who have been studied since infancy by the researchers, were evaluated for "adolescent psychosocial impairment" as defined by the American Psychiatric Association. Among the young women, there was a statistically significant difference in the proportion judged to require psychiatric treatment. Among the SCA females (XO and XXX) that proportion was more than 60 percent, compared with about 10 percent in the control group.

Bender finds that the children with neurocognitive deficits -- language, motor and learning problems -- tend to become the adolescents with psychosocial impairment. Most of these "high-risk" children have language deficits measurable by age 4. But about 40 percent of the SCA subjects have neither the three childhood deficits nor the psychological impairment.

While the scientists cannot fully explain why some children are affected by a chromosomal abnormality more than others, Bender believes the social environment plays an important role. He reports that the "high-risk" children tend to come from families ranked high in stress factors, low in parenting skills and low in socioeconomic status. "Family support, language therapy, special education and individual counseling ... may ameliorate some of the risks of SCA," he speculates. "Our findings have shown that the detection of sex chromosome abnormalities...should alert doctors and parents to the possibility that the child will need extra help throughout childhood and adolescence."