Source: Kelly Klump, Ph.D., Michigan State University
Biological changes associated with puberty may influence the development of binge eating and related eating disorders, according to a recent study on female rats conducted by NIMH-funded researchers. After puberty, the rats showed binge eating patterns that resemble those in humans, supporting the role of biological factors, since rats do not experience pressures to be thin or other psychosocial risk factors commonly associated with human eating disorders. The study was published online ahead of print on May 16, 2011, in the Journal of Abnormal Psychology.
Among girls, symptoms of binge eating or bulimia nervosa often arise around puberty. Past research has largely focused on psychosocial roots for this association, but biological changes that occur during and after puberty are likely to have an effect as well.
Kelly Klump, Ph.D., of Michigan State University, and colleagues tested this theory in an animal model since animals do not experience psychological risk factors during puberty. They used a rat model that can distinguish between rats that are resistant to binge eating (BER) from those prone to binge eating (BEP), based on their individual eating habits.
For this study, the researchers studied binge eating risk from pre-puberty to adulthood in 66 female rats. In addition to their standard food, the rats were provided intermittent access to cake frosting, a highly enjoyable but nutritionally empty and high fat food.
Over the course of development, all rats ate more frosting as they matured. However, a difference in frosting intake between BER and BEP rats emerged during puberty—no differences in frosting intake were observed in pre-puberty, but large differences were observed in puberty and adulthood (see Figure 1)
The researchers noted that rats in the BER and BEP groups ate similar amounts of the standard food and were similar in body weight. This suggests that the BEP rats were not overeaters generally, but were instead, prone to binge eat on high-fat foods only.
The findings reveal dramatic increases in binge eating proneness during puberty, suggesting that increases in binge eating and similar eating disorders during and after puberty in girls may be partially due to biological factors ceus for counselors
Similar to binge eating in humans, BEP rats ate much more of the high-fat food but did not increase their consumption of the standard food. Also, all rats preferred the high-fat food, regardless of developmental stage, which is similar to behaviors seen in girls; for example, girls tend to prefer candy over healthier treats at all ages. In both rats and humans, this behavior begins to diverge during puberty, with some consuming much more of the high-fat food than others.
Unlike humans, however, the percentage of binge eating rats (30 percent) was much higher than estimates in humans (3.5–19 percent). According to the researchers, this difference may indicate that binge eating in rats is a “pure” form of binge eating that is unmodified by psychosocial factors—such as social disapproval or guilt—that tends to decrease binge eating rates in humans.
More research is needed to develop and validate animal models of the cognitive and behavioral symptoms of eating disorders. Studies exploring the mechanisms underlying developmental changes that occur during puberty, for example the action of ovarian hormones, may also inform research on eating disorders.
Klump KL, Suisman JL, Culbert KM, Kashy DA, Sisk CL. Binge eating proneness emerges during puberty in female rats: A longitudinal study. J Abnorm Psychol. 2011 May 16. [Epub ahead of print] PubMed PMID: 21574664.
Source: Kelly Klump, Ph.D., Michigan State University
Adapted with permission from APA
August 28, 2011
August 09, 2011
An extract of the herb St. John's Wort and a standard antidepressant medication both failed to outdo a placebo in relieving symptoms of minor depression in a clinical trial comparing the three. The results of this study, consistent with earlier research, do not support the use of medications for mild depression counselor ceus
St. John's Wort is a plant whose yellow flowers have been the source of extracts used medicinally for centuries. It is widely used to treat depression, as a nutritional supplement in the United States, and as a prescription medication in Europe. Evidence from clinical trials of St. John's Wort has failed to show effectiveness for treatment of major depression; but research has raised the question as to whether the herb might offer benefit for people with less severe depression.
This study, focusing specifically on minor depression, was conducted by Mark Hyman Rapaport and colleagues at the Cedars-Sinai Medical Center and David Geffen School of Medicine in Los Angeles; the Massachusetts General Hospital, in Boston; and the University of Pittsburgh. Participants in the study had minor depression, defined as the presence of two to four symptoms used to diagnose major depression, with at least one symptom being depressed mood or anhedonia, a lack of pleasure in activities usually found enjoyable. Symptoms had to have been present for six months to two years. Subjects were randomly assigned to receive St. John's Wort, the antidepressant medication citalopram, or a placebo. Neither participants, nor the staff treating them, knew what treatment they took. Seventy-three subjects completed the trial.
Results from the trial showed that no treatment relieved depression more than any other; patients in all three of the treatment groups showed improvements in symptoms over the course of the study, and in measures of quality of life and psychological well-being.
Patients in all three treatment groups—including placebo—also frequently reported side effects. In addition, before treatment began in this study, more than half of participants responded positively when they were asked if they had any of a broad list of physical or psychological complaints. This finding suggests that it's important to assess both physical and psychological symptoms even before treatment begins; otherwise, many of these symptoms might be interpreted as medication-related.
While minor depression is by definition a milder condition than major depression, research suggests it has consequences for health and well-being that go beyond the symptoms themselves, including lost work days, social difficulties, and possibly a higher risk of developing future major depression.
The authors are careful to point out that the reason that there was no difference in benefit between St. John's Wort, citalopram, and placebo was not because the study was too small to detect a difference, but because participants taking placebo experienced substantial improvement in measures of depression and well-being—participation in the study had positive effects. In addition, participants taking all three treatments—even those on placebo—experienced side-effects. Fewer of the subjects taking St. John's Wort reported that side effects were distressing (40 vs. 60 percent); but St. John's Wort recipients reported more gastrointestinal and sleep problems than those receiving placebo.
Identifying effective and safe ways to treat minor depression remains an important goal; further research on non-pharmacologic treatment is needed to identify the optimal psychotherapies for minor depression.
This study was funded by the National Institute of Mental Health and the National Center for Complementary and Alternative Medicine, National Institutes of Health.
Rapaport, M.H., Nierenberg, A.A., Howland, R., Dording, C., Schettler, P.J., and Mischoulon, D. The treatment of minor depression with St. John's Wort or citalopram: Failure to show benefit over placebo. Journal of Psychiatric Research 45:931-941, 2011.