Hegeman Judith, Weerdesteyn Vivian, van den Bemt Bart Jf, Nienhuis Bart, van Limbeek Jacques, Duysens Jacques
Department of Research, Development & Education, Sint Maartenskliniek, Nijmegen, The Netherlands.
BMC Res Notes. 2010 Sep 23;3:243. doi: 10.1186/1756-0500-3-243.
Alcohol is a commonly used social drug and driving under influence is a well-established risk factor for traffic accidents1. To improve road safety, legal limits are set for blood alcohol concentration (BAC) and driving, usually at 0.05% (most European countries) or 0.08% (most US states, Canada and UK). In contrast, for walking there are no legal limits, yet there are numerous accounts of people stumbling and falling after drinking. Alcohol, even at these low concentrations, affects brain function and increases fall risk. An increased fall risk has been associated with impaired obstacle avoidance skills. Low level BACs are likely to affect obstacle avoidance reactions during gait, since the brain areas that are presumably involved in these reactions have been shown to be influenced by alcohol. Therefore we investigated the effect of low to moderate alcohol consumption on such reactions.Thirteen healthy senior individuals (mean(SD) age: 61.5(4.4) years, 9 male) were subjected to an obstacle avoidance task on a treadmill after low alcohol consumption. Fast stepping adjustments were required to successfully avoid suddenly appearing obstacles. Response times and amplitudes of the m. biceps femoris, a prime mover, as well as avoidance failure rates were assessed.
After the first alcoholic drink, 12 of the 13 participants already had slower responses. Without exception, all participants' biceps femoris response times were delayed after the final alcoholic drink (avg ± sd:180 ± 20 ms; p < 0.001) compared to when participants were sober (156 ± 16 ms). Biceps femoris response times were significantly delayed from BACs of 0.035% onwards and were strongly associated with increasing levels of BAC (r = 0.6; p < 0.001). These delays had important behavioural consequences. Chances of hitting the obstacle were doubled with increased BACs.
The present results clearly show that even with BACs considered to be safe for driving, obstacle avoidance reactions are inadequate, late, and too small. This is likely to contribute to an increased fall risk. Therefore we suggest that many of the alcohol-related falls are the result of the disruptive effects of alcohol on the online corrections of the ongoing gait pattern when walking under challenging conditions.
酒精是一种常用的社交性毒品，酒后驾车是交通事故的一个公认风险因素1。为提高道路安全，针对血液酒精浓度（BAC）和驾驶设定了法定限制，通常为0.05%（大多数欧洲国家）或0.08%（大多数美国州、加拿大和英国）。相比之下，对于步行没有法定限制，但有大量关于人们饮酒后绊倒和摔倒的报道。即使是这些低浓度的酒精也会影响大脑功能并增加跌倒风险。跌倒风险增加与避障技能受损有关。低水平的BAC可能会影响步态中的避障反应，因为据推测参与这些反应的脑区已被证明会受到酒精的影响。因此，我们研究了低至中度饮酒对这类反应的影响。13名健康的老年人（平均（标准差）年龄：61.5（4.4）岁，9名男性）在低剂量饮酒后在跑步机上进行避障任务。需要快速调整步伐以成功避开突然出现的障碍物。评估了股二头肌（主要运动肌）的反应时间和幅度以及避障失败率。
在饮用第一杯酒精饮料后，13名参与者中有12人的反应已经变慢。无一例外，与清醒时（156±16毫秒）相比，所有参与者在饮用最后一杯酒精饮料后的股二头肌反应时间均延迟（平均±标准差：180±20毫秒；p<0.001）。从BAC达到0.035%起，股二头肌反应时间显著延迟，并且与BAC水平升高密切相关（r = 0.6；p<0.001）。这些延迟产生了重要的行为后果。随着BAC升高，撞到障碍物的几率增加了一倍。
目前的结果清楚地表明，即使是被认为对驾驶安全的BAC水平，避障反应也不充分、延迟且幅度过小。这可能会导致跌倒风险增加。因此，我们认为许多与酒精相关的跌倒都是酒精在具有挑战性的行走条件下对正在进行的步态模式的在线纠正产生干扰作用的结果。
