Researchers who study puberty say it is more than just an awkward phase when boys and girls are primed for their sexual reproductive years as men and women. Puberty also is a delicate and dynamic time in the development of the brain, when important neural pathways essential for behavioral and cognitive functions are formed. Indeed, brains of children going through puberty are especially vulnerable to the effects of marijuana, suggest results of animal research also reported at ICN 2006, which takes place June 19–22 at the David L. Lawrence Convention Center in downtown Pittsburgh.
Summaries of the studies' findings and other research looking at what triggers puberty follow:
Early puberty associated with eating and anxiety problems as young adults
A study involving 1,500 college students suggests that those who experience early puberty are more likely to engage in abnormal eating behaviors and have feelings of anxiety in young adulthood. Interestingly, the researchers found the association not limited to girls. In fact, the study conducted by Julia Zehr, Ph.D., a post-doctoral fellow at Michigan State University, and colleagues, found that both female and male students who reported they'd entered puberty earlier than their friends and peers scored significantly higher for measures related to binge eating, dieting and concerns about food intake, weight or body shape, as well as anxiety.
The findings are consistent with the idea that such behaviors result from long-lasting changes in brain circuitry that occur during early puberty, when a still-developing brain must adapt to the presence of surging hormones. Eating and anxiety disorders often begin during adolescence and are associated with early puberty, so some have held the view that the psychosocial pressures of standing out from one's peers make young kids more vulnerable. Another possibility is that the hormones themselves are to blame. Dr. Zehr points out that if either theory were true, adolescents would eventually grow out of such behaviors, because, eventually, the awkwardness of early puberty goes away and the hormones settle to adult levels. Based on the study's finding that early puberty is associated with increased symptoms in both young men and women, Dr. Zehr believes the influences of puberty are more biological than solely psychosocial.
Marijuana may be more mind-altering than you think: Early exposure can hinder brain development, increase susceptibility to other addictions
Marijuana may indeed be the storied "gateway drug" to other more serious drug addictions, according to researchers from Mount Sinai School of Medicine in New York and the Karolinska Institute in Sweden. Adolescence is a delicate and dynamic time in the development of the brain when important neural pathways essential for behavioral and cognitive functions are formed. It also is a time when teenagers and even pre-teens are likely to first experiment with marijuana.
Researchers have debated whether or not marijuana use during adolescence can affect brain development or cause the user to be more vulnerable to neuropsychiatric disorders and drug abuse later in life. Yasmin Hurd, Ph.D., professor of pharmacology and biochemistry and psychiatry at Mount Sinai, and colleagues, sought to determine exactly what, if any, impact tetrahydrocannabinal (THC), the psychoactive component of marijuana, has on the developing brain and later behaviors. According to their studies, rats exposed to THC during the early developmental stages, had, as adults, higher self-administered heroin intake under mild stressful conditions than rats not exposed to THC during developmental stages. Those exposed showed neural impairments in brain areas linked to reward, stress and anxiety. These impairments can cause dysregulation of the enkephalin system – the brain's natural morphine system – and are implicated in addiction and affective disorders. Dr. Hurd suggests that while these findings are preliminary, they provide evidence that marijuana can have negative and long-lasting effects on the brain.
Naďve no more: Gene puckers up to propel puberty
According to ongoing research, puberty, that awkward phase when boys and girls are primed for their sexual reproductive years as men and women, appears to be triggered by the sudden activation of a particular gene aptly called KiSS-1, which produces the protein molecule called kisspeptin that turns puberty on. In studies involving nonhuman primates, the only animals with a reproductive system in common with the human's, Tony Plant, Ph.D., professor of cell biology and physiology at the University of Pittsburgh School of Medicine, aims to understand puberty's deep-seated neurobiological mechanisms. Such information could help prevent precocious or delayed puberty from occurring in some children.
With the initiation of puberty, the full repertoire of reproductive hormones that existed at birth but had gone into hiding at about six months of age, re-emerges in full force. The onset of puberty becomes official when gonadotropin-releasing hormone (GnRH) is secreted and sets off a chain reaction of chemical messages. Inside the hypothalamus, nerve cells release GnRH in a 'round-the-clock,' pulsatile fashion. With each secretion, the pituitary gland is stimulated to secrete its own messengers, lutenizing hormone (LH) and follicle-stimulating hormone (FSH), directly into the circulation. In turn, these rising levels of LH and FSH cause the testes and ovaries to produce the sex hormones testosterone and estradiol, the culprits responsible for the physical changes and emotional baggage of male and female puberty, respectively. According to Dr. Plant, other molecules are beginning to be associated with the sudden resurgence of GnRH, so it's quite likely there are multiple pathways working together or in parallel.
Held in a different part of the world every four years under the auspices of the International Neuroendocrine Federation, this year's congress – Bridging Neuroscience and Endocrinology – is being sponsored by the American Neuroendocrine Society and the University of Pittsburgh School of Medicine. The first full day of the program, June 20, is being held in conjunction with the 10th Annual Meeting of the Society for Behavioral Neuroendocrinology.
Formerly the International Society of Neuroendocrinology, the International Neuroendocrine Federation consists of six member societies and seven regional groups, representing all parts of the world. The federation's president is John A. Russell, MBChB, Ph.D., chair of neuroendocrinology, University of Edinburgh. The chair of the ICN 2006 scientific program is Iain J. Clarke, Ph.D., professorial fellow in the department of physiology at Monash University in Australia. Tony Plant, Ph.D., professor of cell biology and physiology and director of the Center for Research in Reproductive Physiology, University of Pittsburgh School of Medicine, is chair of the local organizing committee.
NOTE TO EDITORS:
The researchers will discuss their work during a briefing, "The Perils of Puberty," Wednesday, June 21 at 10 a.m., which will be moderated by Selma Witchel, M.D., associate professor of pediatrics, University of Pittsburgh School of Medicine and Children's Hospital of Pittsburgh. All briefings take place in rooms 306-307 of the David L. Lawrence Convention Center, downtown Pittsburgh. Reporters may participate via telephone conference call by dialing 800-860-2442 (from within the U.S.) or 866-519-5086 (from Canada). From other countries, call 001-412-858-4600. To be connected to the briefing you must reference ICN 2006. More information about the meeting and the schedule of briefings are available at http://newsbureau.upmc.com/ICN2006. The press room hours are 8 a.m. to 6 p.m., Tuesday, June 20 through Thursday, June 22; Press room staff may be reached during this time at (412) 325-6080. Otherwise, please call the UPMC News Bureau at (412) 647-3555 or Lisa Rossi at (412) 916-3315 (cell).
Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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