Research update

CrossCurrents

by Mark de la Hey

Antidepressant use linked to reduced alcohol consumption in men, but not women

A study from the Centre for Addiction and Mental Health in London, Ontario, has found that although people with depression consume more alcohol than those who are not depressed, depressed men who use antidepressants have lower alcohol consumption than depressed men who do not use antidepressants. However, this pattern does not hold for women. These findings were based on data from 14,063 individuals who participated in the GENACIS Canada survey. The researchers found that current drinking men who were not depressed consumed an average of 436 drinks during the preceding year, compared with 579 drinks for depressed men who did not use antidepressants, and 414 drinks for depressed men who did use antidepressants. Female current drinkers who did not meet criteria for depression consumed 179 drinks over the past year, whereas depressed women who did not use antidepressants consumed 235 drinks and depressed women who did use antidepressants consumed 264 drinks. The results for men are consistent with previous research; however, the authors note that the lack of similar findings for women could reflect gender differences in the effects of antidepressants, but are also consistent with an alter­native explanation – namely, that the lower alcohol consumption among men who used antidepressants may have been the result of the prescribing physician cautioning men to limit alcohol consumption, because previous research has found that men are more likely than women to be cautioned by their physicians about hazardous drinking. The authors recommend further research to determine whether the gender differences are due to differences in the nature of depression in men and women or to gender differences in the pharmacological effects of antidepressants.

Canadian Medical Association Journal, February 27, 2007, v. 176: 633–637. Kathryn Graham and Agnes Massak, Centre for Addiction and Mental Health, London, Ontario.

 

Researchers closing in on genetic link to autism

An international team of researchers has completed a study that has helped to clarify the genetic basis for autism. The research was conducted as part of the Autism Genome Project, involving scientists from 50 centres in North America and Europe. Researchers analyzed DNA samples from 1,168 families with at least two individuals with autism. They performed the largest genetic linkage scan to date, looking for genetic variants that account for much of the risk in families. Genes are considered linked when they are inherited together, resulting in genetic variations that always occur together. The researchers hypothesized that susceptibility to autism was the result not of any one gene, but rather of a number of genes working together. Linkage analysis led researchers to flag a region on chromosome 11 as a source of risk for autism. The researchers also analyzed copy number variation, defined as the number of copies of a particular gene in any individual’s genotype. They identified genes known as neurexins as contributors to genetic susceptibility to autism, particularly the neurexin 1 gene (NRXN1), thought to play an important role in developing communication between nerve cells in the brain. NRXN1 interacts with neuroligins, proteins on the surface of nerve cells that can contribute to autism when they are affected by mutations. Together, neurexins and neuroligins are important in glutamate function, and glutamate dysfunction is often considered an important risk factor in the development of autism.

Nature Genetics, March 2007, v. 39: 319–328. Bernie Devlin et al, Department of Human Genetics, Graduate School of Public Health, University of Pittsburgh, Pittsburgh, Pennsylvania.

 

Early physical maturity leads to risky behaviour in teens

Teenagers whose physical maturity is in advance of their peers are at risk for problem behaviours, according to research from the University of North Carolina. Teenage girls face an additional risk if they have an older romantic partner. The study involved in-home interviews with 4,118 adolescents under age 15 from the National Longitudinal Study of Adolescent Health. According to self-report, the physical development of 43 per cent of girls in the study was in advance of their peers, compared with 34 per cent of boys. Just over 50 per cent of both sexes had a romantic partner. Twenty per cent of girls had an older partner, com­pared with only four per cent of boys. Teens who were more physically mature than their peers were more likely to have a romantic partner, and among girls, the partner was more likely to be two or more years older. For both sexes, early puberty and early physical maturation were associated with a range of risky behaviours, including experimentation with sex, tobacco, alcohol and other drugs. Having a romantic partner further increased the risk, particularly for girls with older romantic partners. They were 22 times more likely to engage in sexual experimentation, 37 times more likely to combine alcohol use and sexual activity and 93 times more likely to combine heavy substance use and sex. The authors suggest that these increased risks may in part be due to power differentials and different expectations regarding sexual activity among older teens.

Prevention Science, March 2007, v. 8: 1–10. Carolyn Tucker Halpern et al, Department of Maternal and Child Health, University of North Carolina, Chapel Hill, North Carolina.

 

Improving school ethos reduces substance abuse and teenage pregnancies

Efforts to improve school ethos (institutional culture) can help to reduce substance abuse and teen pregnancy, according to studies included in a recent survey from the London School of Hygiene and Tropical Medicine in the United Kingdom. Such efforts focus on improving student engagement in school activities and the quality of teacher-student relationships. Current classroom interventions aimed at educating students about substance abuse and sexual behaviour have had little impact. One Scottish study found that significantly lower rates of drug, alcohol and tobacco use in some secondary schools were best explained by small school size and superior school ethos, rather than by measures of student, family or neighbourhood factors. A project to improve school ethos among high school students in Chicago resulted in a 34 per cent reduction in combined alcohol, tobacco and cannabis use among boys, as well as significant benefits with respect to condom use, frequency of sex, violence and truancy. However, it did not find comparable benefits among girls. Finally, an Australian study evaluated an intervention in 26 Australian schools aimed at curbing bullying and improving student-teacher communication, students’ self-esteem and student participation. These efforts resulted in fewer risky behaviours such as smoking, drinking and cannabis use. The authors suggest that teens who enjoy school and value the qualifications obtained in school may be less likely to view substance use or early parenthood as markers of adult behaviour or as ways of finding meaning or gaining the respect of peers.

British Medical Journal, March 24, 2007, v. 334: 614–616. Chris Bonell et al, Centre for Research on Drugs and Health Behaviour, London School of Hygiene and Tropical Medicine, London, UK.

 

• Print Share