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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 and Maisto 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 (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).Bec...