Comparison between subjective feelings to alcohol and nitrogen narcosis: a pilot study

Narcotic Nitrogen Effects Persist after a Simulated Deep Dive

Background and Objectives: Scuba divers often experience persistent inert gas narcosis (IGN) even after surfacing. This study aimed to test the hypothesis that breathing oxygen (O2) before surfacing can reduce postdive IGN. Materials and Methods: A group of 58 experienced divers underwent a 5 min dive at a depth of 50 m in a multi-place hyperbaric chamber. They were decompressed using air (air group). Another group of 28 divers (O2 group) breathed 100% O2 during the end of decompression. Prior to and after the dive, all participants performed the Sharpened Romberg test (SRT) and a modified tweezers test. Results: In the air group, the number of positive SRT results increased postdive (47% vs. 67%), indicating a greater impairment in the vestibular system (Cohen's d = 0.41). In the O2 group, the percentage of positive SRT results remained constant at 68% both before and after the dive. In terms of the modified tweezers test, the air group showed no significant change in the number of picked beads (40 ± 9 vs. 39 ± 7), while the O2 group demonstrated an increase (36 ± 7 vs. 44 ± 10) (Cohen's d = 0.34). Conclusion: The results reveal that the SRT revealed a negative effect of nitrogen (N2) on the vestibular system in the air group. The increased number of beads picked in the O2 group can be attributed to the learning effect, which was hindered in the air group. Consistent with our hypothesis, breathing O2 during decompression appears to reduce postdive IGN.

Studies on the sensitivity to alcohol and alcohol dependence

The role of genetic and environmental factors in the development of alcohol dependence is beginning to be investigated in Brazil. This paper reviews recent studies on genetic aspects of alcohol use and alcohol dependence, with emphasis on those carried out in Brazilian populations. Most findings replicated studies in developed countries, while some indicate new possible venues for investigation in the future. They underscore the need for a cross-cultural and interethnic approach to biomedical aspects of alcohol use and dependence.

The effects of alcohol history on the reinforcing, subjective and psychomotor effects of nitrous oxide in healthy volunteers

The purpose of this study was to characterize the reinforcing, subjective and psychomotor effects of nitrous oxide in healthy volunteers with different alcohol histories. Subjects were divided into two groups: light drinkers (n = 9) and moderate drinkers (n = 10). A choice procedure was used in which subjects first sampled placebo and a given concentration of nitrous oxide, and then chose between the two. Nitrous oxide concentration varied across the four-session experiment from 10-40%. Besides choice, subjective and psychomotor effects served as dependent measures. The majority of subjective effects of nitrous oxide, and its psychomotor-impairing effects, did not vary as a function of drinking group. However, a Wilcoxon rank sum test showed that the median number of times moderate drinkers chose nitrous oxide (three) was significantly higher than the median number of times light drinkers chose nitrous oxide (one). This study provides suggestive evidence that the reinforcing effects of nitrous oxide are modulated by alcohol history.