In brief

• Regular exercise may be better than mental or social activities in protecting older people's brains from shrinking, finds research conducted at the University of Edinburgh in Scotland. Researchers examined the medical records and MRI scans of 638 older adults. They also asked the participants about their exercise habits and participation in social and mentally stimulating activities. The researchers found that after three years, people who participated in more physical activity experienced less brain shrinkage than those who exercised minimally. (Neurology, Oct. 23)

• Half of drug and alcohol abuse counselors find it acceptable for some of their patients to have an occasional drink, according to a study led by psychologists at Bowling Green State University. Researchers surveyed 913 members of the National Association of Alcoholism and Drug Addiction Counselors and found that about 50 percent said it would be acceptable if some of their clients who abused alcohol wanted to limit their drinking but not totally give up alcohol — double the number finding it acceptable in a similar survey done in 1994. At the same time, however, 75 percent of clients with alcohol or drug dependence — which is considered more severe than alcohol or drug abuse — said they would not approve of limited or moderate consumption, as either an intermediate or final therapy goal. (Psychology of Addictive Behaviors, online Oct. 22)

• People may make more ethical decisions when they think their heart is racing, finds research conducted at the University of British Columbia and the University of Toronto. In one experiment, scientists asked 65 undergraduates to wear a bogus heart rate monitor attached to a headset playing normal or fast heartbeat sounds. The students then played a money-sharing game in which they decided whether to instruct their partner, located in another room, to pick option A — which was actually more lucrative for the student — or option B, which was more lucrative for the partner. Participants who heard their heart beating at a normal speed were about twice as likely to lie and tell their partners that they would be better off choosing option A than those who heard their heart beating fast. The participants may have interpreted their racing heart as a sign of stress, prompting them to adhere to moral conventions to escape that stress, the researchers posit. (Journal of Experimental Psychology: General, online Aug. 13)

• Most teens who have attempted or are thinking about suicide have not received mental health services, according to a national survey of more than 10,000 U.S. adolescents. The survey, led by a researcher at the National Institute of Mental Health, found that 3.6 percent of adolescents reported suicidal ideation without a plan or attempt, 0.6 percent reported a suicide plan without an attempt and 1.9 percent made a suicide attempt. Two-thirds of adolescents with suicidal ideation and half of those with a plan or attempt did not have any contact with a mental health specialist in the past year. (Psychiatric Services, October)

• Teasing and bullying are linked to an increase in high school dropout rates, according to research conducted at the University of Virginia. This study of 281 Virginia public high schools found that when ninth-graders perceived an atmosphere of bullying, they were more likely to drop out of high school than when bullying was not as rampant in their school. The findings were true even after controlling for the effects of school size, economic and racial/ethnic composition of the student body, and performance on standardized testing. (Journal of Educational Psychology, online Oct. 22)

• Being bullied is particularly damaging to the mental health of girls who receive no social support from adults or friends, finds a study by psychologists at the University of British Columbia who studied more than 3,000 10-year-olds from 72 schools in Vancouver. The researchers found that positive relationships with adults and peers were strongly linked to life satisfaction and self-esteem, whereas bullying was strongly linked to low life satisfaction, low self-esteem and more depressive symptoms in girls who also had low levels of social support from adults and peers. They also found that social support from adults or friends — or both — lessens the negative consequences of bullying, including anxiety and depression. (Journal of Happiness Studies, online Oct. 3)

• Birth control pills may help prevent Alzheimer's disease, according to a study conducted at the University of Wisconsin. Researchers administered a series of cognitive tests to 261 cognitively healthy women age 45 to 65. They found that women who had taken birth control pills scored higher on cognitive tests of visuo-spatial ability, speed and flexibility than women who had never taken them — and these effects could be seen for years after the women had stopped taking the pill. They also found that the longer women took the pill, the better they performed on the tests. These results may be a result of estrogen modulating and even improving these areas of function, the researchers suggest. (Journal of Women's Health, online Sept. 20)

• Media coverage of natural disasters may cause post-traumatic stress disorder in anxious children exposed to the disaster, according to research by psychologists at the University of New Orleans. The researchers followed 141 children who had lived in areas hit hard by Hurricane Katrina, measuring their PTSD symptoms 24 and 30 months after the event. They also followed up with the children one month after a different hurricane, Gustav, hit the area two years later and asked them about how much television they had watched about the hurricane. They found that for children who displayed symptoms of anxiety before Gustav, the more hurricane-related coverage they watched, the more likely they were to experience PTSD. (Psychological Science, online Oct. 15)

• Signs of Alzheimer's disease may appear up to 20 years before diagnosis, finds research conducted at University College London. Researchers scanned the brains of 44 young adults age 18 to 26. Twenty tested positive for the presenilin 1 (PSEN1) gene mutation — which has been linked to early-onset Alzheimer's — but had not shown any symptoms of the disease. They found that, compared with those without it, participants with the PSEN1 mutation had more activity in the hippocampal and parahippocampal areas of their brains and less gray matter in certain brain regions. Those with the mutation also showed more amyloid beta protein — a precursor to plaque, a key marker of Alzheimer's — in their cerebrospinal fluid. (The Lancet Neurology, online Nov. 6)

• Teens who were born extremely prematurely with very low birth weights are more likely to have serious anxiety problems than teens born full-term and with normal birth weights, according to a meta-analysis by researchers at the University of Copenhagen. The analysis reviewed six studies with a total of more than 1,500 adolescents; 787 were born before 32 weeks gestation and weighed less than 3.3 pounds, and 732 were born full term with normal weight. Prematurity and low birth weight more than doubled the risk of anxiety symptoms, but the effect seemed to diminish after age 15. (Developmental Medicine & Child Neurology, November)

• Men and women use different spatial memory techniques to find their cars in crowded parking lots, according a study led by psychologists at Utrecht University in the Netherlands. The researchers visited a mall and asked 115 people to estimate the distance from the mall exit to their cars, to point to their cars on a map of the parking lot, and to describe the route and strategies they might use to locate their cars. They found that women tended to rely more on visible landmarks and took substantial detours, while men were better at estimating distances and more likely to take a direct route to the vehicle. (Applied Cognitive Psychology, September/October)

• High levels of family stress in infancy may sensitize girls' brains for later anxiety, according to a study by University of Wisconsin–Madison scientists. The researchers used functional connectivity MRI to scan the brains of 57 adolescents and compared the data with parental reports of stress when the adolescents were newborns and at several points throughout their lives. The researchers found that babies who lived with stressed mothers were more likely to grow into preschoolers with higher levels of cortisol. In addition, girls with higher cortisol also showed less communication between brain areas associated with emotion regulation 14 years later, and both high cortisol and differences in brain activity predicted higher levels of adolescent anxiety at age 18. The young men in the study did not show any of these patterns. (Nature Neuroscience, online Nov. 11)

• We spend more with worn bills than with crisp bills, finds research completed at the Universities of Winnipeg and Guelph. In one experiment, for example, in which participants could either lose their original $10 or win $20, and the odds of winning or losing the money were the same, more than two-thirds of those who had a wrinkled $10 bill and were offered a new $20 bill chose to gamble. Less than a third of the participants who had a new $10 bill and were offered a beat-up $20 bill chose to take the risk. The investigators also found that participants were more likely to break a wrinkled larger bill than pay the exact amount in crisp ones. This may be because we tend to infer that worn bills are used and contaminated so we want to get rid of them, whereas crisp bills give us a sense of pride. (Journal of Consumer Research, in press)

• Oxytocin may promote fidelity, according to research by University of Bonn investigators. The researchers administered oxytocin or a placebo via a nasal spray to a group of healthy, heterosexual males and then introduced them to a woman experimenter whom they later described as "attractive." As the experimenter moved toward or away from the study volunteers, the men were asked to indicate when the experimenter was at an "ideal distance," as well as when the experimenter moved to a distance that felt "slightly uncomfortable." The researchers found oxytocin led the men in committed relationships, but not those who were single, to keep a greater distance between themselves and the woman. In a separate experiment in the same study, the researchers found oxytocin had no effect on the distance men kept between themselves and a male experimenter. (The Journal of Neuroscience, Nov. 14)

—Amy Novotney