Vol. 22 Issue 5
Many Factors Contribute to Autism and ADHD
Many factors can contribute to or worsen disorders such as autism and attention deficit hyperactivity disorder (ADHD), suggests an analysis by a neuroscientist at UCLA. A novel model of brain development and degeneration identifies the disruption of myelination as a key neurobiological component behind childhood developmental disorders (Adolescent Psychiatry, in press 2005).
The analysis also suggests that alcohol and other drugs of abuse have toxic effects on the myelination process in some adolescents, contributing to poor treatment outcomes and exacerbating co-existing psychiatric disorders.
The high incidence of impulsive behaviors that characterize the teen years and the many psychiatric disorders that occur in the teens and 20s are related to incomplete myelination of inhibitory "stop" brain circuits, concluded study author George Bartzokis, MD, a professor of neurology at the David Geffen School of Medicine at UCLA. The "go" circuits become fully functional earlier in development. Inhibitory circuits are not on line to quickly interrupt high-risk behaviors that are so prevalent in teens and young adults.
"Myelination, a process uniquely elaborated in humans, arguably is the most important and most vulnerable process of brain development as we mature and age," said Dr. Bartzokis, director of the UCLA Memory Disorders and Alzheimer's Disease Clinic and the Clinical Core of the UCLA Alzheimer's Disease Research Center.
"Environmental toxins, genetic predispositions and even diet appear to influence and sometimes disrupt this process," he added. "By shifting our research focus to medications that act on brain metabolism and development, as opposed to brain neurotransmitter chemistry, neuroscientists will likely find a wealth of novel opportunities for addressing the cause of brain disease rather than simply the symptoms."
Myelin is a sheet of lipid, or fat, with very high cholesterol contentthe highest of any brain tissue. This high cholesterol content allows myelin to wrap tightly around axons, speeding messages through the brain by insulating these neural "wire" connections.
The analysis by Dr. Bartzokis of magnetic resonance images (MRIs) and post-mortem tissue data suggests that myelin production is a key component of brain development through childhood and well into middle age, when development peaks and deterioration begins. He also identifies the midlife breakdown of myelin as a key to the onset of Alzheimer's disease later in life.
"This model of a lifelong trajectory of brain development and degeneration embraces the brain as a high-speed Internet rather than a computer," he said. "The speed, quality and bandwidth of the connections determine the brain's ability to process information; and all these depend in large part on the insulation that coats the brain's connecting wires."
The research was funded by the National Institute of Mental Health, Department of Veterans Affairs, National Institute of Aging, and Alzheimer's Disease Research Center of California.
Little Evidence of Applied Learning Outside Class
While students spend a chunk of their day inside the classroom, a key purpose of schooling is what they do outside of school with what they've learned. For example, did a lesson on the Revolutionary War motivate a student to pick up a book on the subject at a local library or make a trip to the history museum to learn more? A new study by the University of Missouri-Columbia found little research exists on the topic and suggests that school learning has less of an influence on life experience and interests than school professionals expect.
"We are concerned with how students use their academic learning to enrich their lives," said David Bergin, PhD, associate professor of educational, school and counseling psychology in the College of Education at the university. "Do they get so interested in anything in school that they learn more about it outside of school? Do they learn something that makes them see the world in a new way?"
For their study, published recently in Educational Researcher, Dr. Bergin and co-author Kevin Pugh, PhD, assistant professor of education at the University of Toledo, examined research on the effect a subject matter has on a student's everyday experience outside the classroom. One finding was that students love field trips because they are novel and fun, not because they anticipate learning new things. Nevertheless, teachers can make field trips educationally profitable for students if they carefully prepare them for what they should learn, Dr. Bergin said.
Some students acquire interest in school-based content, current research suggests. For example, some students might become interested in literature and read unassigned plays and novels. However, the rate of such school-prompted interest appears to be relatively low.
This study serves as a critique of educational research, which has done little to study what students do with their learning, Dr. Bergin said. "How can we know what students do with their learning if we don't ask that question? In today's environment of testing, researchers and parents want to know what student test scores were, not if there has been any influence on students' interests or activities."
Much more attention should be focused on the transfer of school learning to the out-of-school setting, the researcher said. A general finding in transfer studies is that students are often unable to apply their in-school learning to real-world problems or novel contexts.