Original ArticlesDevelopmental changes in postural sway in children at high and low risk for developing alcohol-related disorders
Introduction
Several studies have investigated differences in postural sway between individuals at high and low risk for alcoholism, either in a baseline condition Hegedus et al 1984, Hill and Steinhauer 1993b, Hill et al 1987, or both at baseline and following administration of varying doses of alcohol Behar et al 1983, Lex et al 1988, Lipscomb et al 1979, McCaul et al 1991, Nagoshi and Wilson 1987, O’Malley 1985, Schuckit 1985. Five studies have found differences in the amount of sway produced by high-risk in contrast to low-risk subjects Hegedus et al 1984, Hill and Steinhauer 1993b, Hill et al 1987, Lester and Carpenter 1985, Lipscomb et al 1979. Results of studies assessing postural sway following alcohol consumption in persons at high or low risk for developing alcoholism have varied in outcome, with some showing greater sway in high-risk persons (McCaul et al 1991), while others have found lesser sway Lex et al 1988, Schuckit 1985. None of these studies found differences between the family history positive and negative groups at baseline, however. It is of interest that those studies finding baseline differences all involved minor children except for one report (Lipscomb et al 1979). Therefore, the age of the subjects tested appears to be an important factor in detecting baseline differences in sway.
The human postural control system is highly complex, involving the integration of information from three sensory systems: proprioceptive, visual, and vestibular, with adjustment of postural muscles maintaining body posture in response to these sensory inputs Ghez 1991, Nashner and McCollum 1985. All of the sensory afferents converge toward the vestibular nuclei of the brainstem, where they are integrated and result in induction of the motor reflex responses. Motor control similarly involves multiple influences, including stretch receptors and long loop reflexes, which are influenced by supraspinal input from higher motor control programs. Thus, stability during upright stance depends on vestibular function and to a large extent, vestibulospinal function. However, stability also depends on sensory input including vision, somatosensation, and motor control, especially that concerned with the lower extremities and the trunk (Furman 1995). Due to the importance of vision and the oculomotor control involved in maintaining balance, closing the eyes during performance of balance tests increases sway both in a no alcohol condition Hill and Steinhauer 1993b, Hill et al 1987 and when the tests are performed following alcohol administration (Ledin and Odkvist 1991). Results of these studies suggest the importance of vestibular and oculomotor integration.
As is the case with other types of motor performance, balance appears to improve with age in children Odenrick and Sandstedt 1984, Usui et al 1995 and decline with advancing age in older adults Perrin et al 1997, Schultz et al 1997. In children, postural sway has been shown to decrease markedly between the ages of 3 and 5 years and then slowly after age 6, with boys showing more sway under the age of 10 than girls (Usui et al 1995).
Because previous studies have demonstrated greater sway in high-risk than low-risk children Hegedus et al 1984, Hill and Steinhauer 1993b, Hill et al 1987, Lipscomb et al 1979 and age-related changes in sway during childhood have been noted (Usui et al 1995), we hypothesized that the familial risk differences previously observed might be due to a developmental delay in acquiring age-appropriate levels of balance among high-risk children.
Section snippets
Recruitment of pedigrees
A total of 126 high and low-risk children between the ages of 8 and 18 years participated in the study. The children were drawn from families that were part of a larger family study of alcoholism (Cognitive and Personality Factors in Relatives of Male Alcoholics), which included families chosen either for a high density of alcoholism (high-risk families) or families chosen for an absence of alcoholism and most major psychopathology (low-risk families).
High-risk children
High density for alcoholism families had
Analysis of variance
The effect of having the eyes closed versus open and the effects of gender on sway may be seen in Figure 1. These variables, along with risk group and age, were evaluated using a four-factor analysis of variance with three grouping and one within factor (BMDP 2V). The analyses were performed for the distance R variable for each of the four sway stances (Lipscomb, Romberg, left monopedal, right monopedal) to test the effects of risk group (high-risk vs. low-risk), gender (male and female), age
Discussion
A number of studies have investigated sway in children at high risk for developing alcoholism, comparing them to control children without family histories of alcoholism. College-aged students or young adults under the age of 30 years have frequently been studied because a number of investigators have tested the effects of alcohol administration on sway in family history positive and negative subjects Lex et al 1988, Lipscomb et al 1979, McCaul et al 1991, Nagoshi and Wilson 1987, Schuckit 1985.
Acknowledgements
This research is supported by grants from the National Institute on Alcohol Abuse and Alcoholism, AA05909 and AA08082.
We thank Joseph Furman, MD, PhD, Department of Otolaryngology, University of Pittsburgh Medical Center for reviewing the manuscript and providing helpful suggestions. Also, we are grateful to Susan Whitney, PhD, for providing data from patients evaluated on a similar sway platform system for validation of our results. Also, our research group is indebted to the families who
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