Teens with slower performance on a test of "cognitive processing speed" are more likely to have depression and anxiety symptoms as adults, reports a paper in Psychosomatic Medicine: Journal of Biobehavioral Medicine, the official journal of the American Psychosomatic Society. The journal is published by Wolters Kluwer.
"Adolescents with slower processing speed may be at increased later risk of anxiety and depression," according to the new research by Catharine R. Gale, PhD, of Edinburgh University and colleagues. The results add new evidence that lower cognitive ability may be a contributor to depression, rather than a consequence of it.
Slower Processing Speed Linked to Depression 20 Years Later
The researchers analyzed data from 705 Scottish participants in a study including follow-up from adolescence into adulthood. At age 16, the participants were evaluated on a simple test of cognitive processing speed—reaction time in pressing keys corresponding to numbers (1 to 4) flashed on a screen.
At age 36, the participants completed standard questionnaires assessing depression and anxiety symptoms. The relationship between reaction time in adolescence and mental health in adulthood was assessed, with adjustment for a wide range of other factors (education, lifestyle habits, etc).
Slower cognitive processing speed—that is, longer reaction time—at age 16 was associated with increased anxiety and depression symptoms at age 36. After adjustment, the relationship remained significant for one of the two mental health questionnaires (the General Health Questionnaire), but not the other (the Hospital Anxiety and Depression Scale).
Smoking appeared to play a role in the relationship between teen reaction times and adult depression scores. "This might at least in part reflect the use of cigarettes as a method of relieving or coping with psychological symptoms," Dr. Gale and coauthors write.
The researchers were also interested in assessing the role of the cumulative effects of stress over time, or "allostatic load." As reflected by various measures related to stress—for example, blood pressure and general inflammation—allostatic load seemed to at least partly account for the link between reaction time and anxiety/depression symptoms. However, this relationship was no longer significant after adjustment for other factors.
Previous studies have shown that people with more severe depression have slower reaction times and other cognitive deficits. It has generally been assumed that this "psychomotor slowing" is a consequence of depression, rather than a risk factor for it. The new study suggests that slower processing speed may contribute to the development of mental health disorders—possibly by leading to "increased stress and difficulties responding to adversity earlier in life."
Dr. Gale and colleagues note some key limitations of their study, especially the fact that the participants had a narrow range of depression scores. The researchers conclude, "Further prospective studies of the relation between reaction time and mental health outcomes in other samples are needed to gauge whether reaction time is a true risk factor for mental disorders and to confirm the mediating roles played by smoking and allostatic load."
Article: "Reaction Time in Adolescence, Cumulative Allostatic Load, and Symptoms of Anxiety and Depression in Adulthood: The West of Scotland Twenty-07 Study. (doi: 10.1097/PSY.0000000000000189)
About Psychosomatic Medicine
Psychosomatic Medicine, Journal of Biobehavioral Medicine, founded in 1939, is the official peer-reviewed journal of the American Psychosomatic Society. It publishes experimental and clinical studies dealing with various aspects of the relationships among social, psychological, and behavioral factors and bodily processes in humans and animals. Psychosomatic Medicine, Journal of Biobehavioral Medicine is an international, interdisciplinary journal devoted to experimental and clinical investigation in behavioral biology, psychiatry, psychology, physiology, anthropology, and clinical medicine. The print journal is published nine times a year; most articles are published online ahead of print.
About the American Psychosomatic Society
The mission of the American Psychosomatic Society is to promote and advance the scientific understanding and multidisciplinary integration of biological, psychological, behavioral and social factors in human health and disease, and to foster the dissemination and application of this understanding in education and health care.
The American Psychosomatic Society is a worldwide community of scholars and clinicians dedicated to the scientific understanding of the interaction of mind, brain, body and social context in promoting health. The organization is devoted to biopsychosocial research and integrated clinical care, and to providing a forum via its website, Annual Meeting and journal, Psychosomatic Medicine, for sharing this research. Its members are from around the world, including specialists from all medical and health-related disciplines, the behavioral sciences, and the social sciences.
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