Abstract
From a preventive medicine perspective, strategies to promote healthy lifestyles in youth often have as much to do with reducing long-term risks as seeking immediate beneficial outcomes. In the latter category, certainly, we seek to provide protective immunizations in young children and prevent automobile accidents and educate against risky sexual behaviors in those who are older. But from a broader, population-based viewpoint, we wish as well to establish healthy lifestyles in youngsters that will persist through a lifetime and pay health dividends as the child grows to be an adult.
The 10-year-old boy who is obese, has low bone mineralization, or has high blood pressure is going to be at increased risk for the complications of type 2 diabetes, for hypertensive stroke, and for bone fractures from osteoporosis in the later years of life. The point is a critical one. The major causes of morbidity and mortality in advanced countries, particularly those resulting from atherosclerosis and excessive accumulation of body fat, are processes that are characterized by a natural course that often begins during the pediatric years. The “pediatric rationale” for preventive medicine rests largely on the idea, then, that reducing the development of such pathologic processes early in life will lessen their impact on the health of the individual later on in the adult years.
Proving that early risk factor reduction in children will prevent clinical expressions of lifelong pathologic processes in adulthood is highly challenging. Indeed, scientific verification of this concept may never be at hand. However, the idea is intellectually sound and has served as the basis for major preventive health initiatives in the pediatric population. Indeed, it is difficult to consider a public health strategy that has greater potential for improving the well-being of the general population.
The major causes of morbidity and mortality in advanced countries . . . are processes that are characterized by a natural course that often begins during the pediatric years
In this issue, Dr Joan Meek has nicely outlined a number of the “battle fronts” on which this attack on unhealthy lifestyle practices in children is being conducted. In this review, the opportunities for altering maladaptive behaviors and improving the health outlook of the individual child as well as the collective population are obvious. Through improved exercise habits, optimal diets, and reduction of high-risk behaviors the argument is compelling that there is an enormous amount to be gained from establishing healthy lifestyles in our youth.
While the importance of taking advantage of this “window of opportunity” for promotion of healthy lifestyles in children and adolescents would seem intuitively obvious, a good number of obstacles face the development of such initiatives. These challenges provide a “future directions” for those attempting to better understand the “pediatric rationale” and for optimizing its implementation in the health care arena. Here is a short list of examples:
The scientific basis of a link between lifestyle behaviors in youth and disease outcomes needs to be better understood and documented.
Many of the presumed behavior–health links in children and adolescents have been extrapolated from those that have been well documented in adult populations. That certain cause-and-effect relationships can be assumed in immature, growing subjects needs to be documented. For example, regular exercise in adults often favorably alters serum lipid profiles, whereas interventions of physical activity in youth typically fail to exhibit this effect. Does this mean that the mechanism for such a response is not active in the pediatric population? Or are other factors involved (different needs for intensity, duration, etc, of the exercise program)?
New diagnostic techniques may provide a better “window” on health risks in children and the role of lifestyle behavior modification. For example, the large gap in time between the obese 12 year old and his myocardial infarction at age 50 has made it very difficult to confirm the effect of obesity prevention on future health. However, new ultrasound methodology (such as flow-mediated dilatation) provides a means of actually viewing the status of the peripheral vasculature and identifying early changes that can lead to atherosclerotic disease outcomes.
Such methodology is in the early stages of development, and many questions remain to be answered. Early studies indicate that adverse vascular changes (ie, those predictive of future atherosclerosis) are already evident in obese youth and those with familial hypercholesterolemia. (The encouraging news is that such alterations seem to be at least partially reversible through dietary and exercise interventions at this age.)
Whether such early vascular function can be related to risk in the general pediatric population (ie, those who are nonobese and normotensive with a normal serum lipid profile) remains to be determined. That information would be crucial in deciding whether dietary and activity interventions should be targeted to the population at large or limited to those who exhibit adverse health risk factors.
The expectation that health-related habits instituted in children will persist (ie, “track”) into the adult years needs to be confirmed.
The concept of childhood as the “formative years” when habits are established for a lifetime is a basic tenet of lifestyle interventions in the young. Such an approach emphasizes creation of habit rather than satisfying certain qualitative thresholds for healthy behavior (ie, minutes per day of physical activity). But there is currently little documentation that dietary or physical activity habits in a 6-year-old girl will be predictive of those when she is 40 years.
Current studies in which physical activity levels in the early years of life have been examined as predictive of those in adulthood have not demonstrated an impressive degree of tracking. But such investigations have been hampered by lack of an accurate measure of habitual activity, and often participation in organized sports has been used (questionably) as a surrogate marker. Moreover, the key question has not yet been addressed: If one intervenes to increase activity levels in a child, will that augmented activity persist for a life time?
The effectiveness of different venues for lifestyle promotion needs to be better identified.
The relative importance of the roles of parents, peers, teachers, and physicians in trying to establish healthy lifestyles in children and adolescence is not altogether clear. The home and school, for instance, might easily be assumed to exert the most powerful influence on children’s behaviors. But unsettled family conditions at home and the reduced role of physical education and health education in the schools can limit the effectiveness of interventions in these venues.
The medical profession is now beginning to accept its role as a key component of lifestyle promotion. The counsel of a physician clearly bears a great degree of credibility. But a number of significant barriers exist that may limit the role of physicians in lifestyle interventions, particularly in respect to physical activity. There is precious little time in the office setting for presenting and following a specific activity prescription, physicians are not adequately trained nor compensated for such a role, and an off-the-shelf evidence-based activity intervention is not currently available. It may be that the role of the physician in activity interventions will be that of identifying the patient at risk and referring him or her to an exercise specialist (similar to referral to a nutritionist for dietary prescriptions).
Interventions for improving the dietary and exercise habits of children have been fragmentary. Means of coordinating the various components of healthy lifestyle promotion need to be identified and effected.
Identifying dose–effect relationships for lifestyle behaviors in youth need to established.
At present, guidelines for amount of regular daily activity that would provide health benefits in children have been based on “educated guesses” by expert committees. Little hard data are available, in fact, on which to base such recommendations. The concept of thresholds of behavior that would produce a healthy outcome in a child requires an accurate means assessing the quantitative aspects of the behavior. At present, considerable progress has been made in measuring habitual physical activity in children, for example, but a highly precise method remains elusive.
Proper and feasible targets for interventions need to be identified.
Should efforts be targeted on promoting a proper diet for all children? Recent advisories have sought more universal cholesterol screening in the population at large. Or should money and efforts be spent on identifying the particular child at risk (by family history, for instance) through screening and focused behavior modification? The issue was raised above in the discussion that new diagnostic techniques might just be able to answer the question.
Despite these and other challenges, good progress has been made in identifying those behaviors in children that place the individual youth at risk for future health issues. The broad picture painted by Dr Meek in her review provides an impressive body of possible avenues for public health initiatives. Considering the potential for enhancing the health of the population, there can be little question that expanded efforts to understand the role of lifestyle modification in children and adolescents for their present and future health is highly warranted.