Alcohol may be neuroprotective in trauma.

CHICAGO -- Alcohol may actually protect the cognitive health of some patients who sustain a head injury while intoxicated, Rael Lange, Ph.D., said at the annual meeting of the Research Society on Alcoholism.

His conclusion stands in stark contrast to the extant literature, which almost universally finds poorer cognitive outcomes in intoxicated patients with traumatic brain injury. But this study contains a critical difference from every other examination of this issue, said Dr. Lange of the University of British Columbia, Vancouver: It excluded patients with a prior history of excessive alcohol use.

"Many patients who are intoxicated at the time of injury have a significant history of chronic alcoholism," he said in an interview. "The exclusion of patients with preinjury alcohol use ensured that what we were studying was the effect of day-of-injury alcohol intoxication, rather than day-of-injury alcohol intoxication complicated by the effects of long-term alcohol misuse."

His retrospective study included 36 patients treated for traumatic brain injury (TBI) at a single hospital; 18 of them were intoxicated at the time of the injury, with a blood alcohol level of at least 100 mg/dL. These patients were matched with 18 others with similar baseline characteristic and similar injuries, but who had no alcohol in their system at the time of injury. Chart review and a neuropsychiatric interview ensured that none of the study group had any significant history of preinjury alcohol use.

This was no easy task, Dr. Lange noted. "It's difficult to study the effects of day-of-injury alcohol intoxication free from the influence of preinjury alcohol intoxication because there is a low prevalence of patients who are intoxicated at the time of injury who do not have a significant history of alcohol abuse. It takes a long time to collect enough participants in this important experimental group. We were fortunate to have access to a large database of trauma patients that were seen over a 7-year period."

The patients' mean age was 27 years; 70% were male. Their average educational level was 12 years. Motor vehicle accident without seat belt was the most common method of injury (42%), followed by motor vehicle accident with seat belt (11%), and pedestrian struck by motor vehicle (11%). Falls, blows to the head, and assault caused the remainder of the injuries.

One-third of the group sustained a mild TBI with skull fracture; one-third, a complicated mild TBI; and one-third, a severe TBI. Most (70%) had a Glasgow coma score of 13-15; the GCS for the remaining patients was 3-8. Loss of consciousness occurred in 70%, did not occur in 11%, and was unknown in the rest.

All patients underwent a battery of 13 cognitive tests within 9 days of their injury. Whether raw scores, percentiles, or scores that excluded the lowest and highest percentile were considered, intoxicated patients scored significantly better on more of the tests than did sober patients.

With the 10th percentile cutoff, low scores on one or more items occurred in 33% of the intoxicated patients and 78% of sober patients. Low scores on two or more items occurred in 17% of the intoxicated and 31% of the sober patients; and low scores on three or more items, 11% of the intoxicated and 39% of the sober patients.

For raw scores, intoxicated patients scored significantly better on 6 of the 13 measures (those measuring delayed verbal memory, delayed visual memory, and executive functioning), and better--but not significantly so--on 4 other tests (those measuring immediate verbal and visual memory, immediate attention span, and verbal fluency).

Several factors may account for the findings, Dr. Lange said. Most similar studies have focused on long-term, rather than short-term, cognitive outcomes, and there may be a long-term recovery trajectory that his study did not capture. Additionally, studies that have not controlled for preinjury alcohol abuse may be drawing biased conclusions about the effect of day-of-injury intoxication.

However, he pointed out, the possibility that acute intoxication protects the brain from injury cannot be excluded. Some animal research has found that small to moderate doses of alcohol (1-2.5 g/kg) may have a neuroprotective effect on the brain at the time of injury because of the inhibition of N-methyl-D-aspartate-mediated excitotoxicity. In humans, some studies have suggested that moderate doses of alcohol are associated with reduced mortality.

"There were a number of hypotheses we considered to explain the unusual findings of this study," Dr. Lange said. "However, we rejected the majority of them. One explanation that we were unable to discount was the 'neuroprotection' hypothesis. We put this hypothesis forward based on several animal studies that have suggested that there may be a number of complex neurophysiologic processes that are altered at the time of injury due to moderate alcohol intoxication."

These neurophysiologic processes are not fully understood, however. "We must consider this explanation of our findings to be speculative at best," he said.

BY MICHELE G. SULLIVAN

Mid-Atlantic Bureau Traumatic Brain Injury Patients With Low Scores on at Least One Cognitive Test Intoxicated patients (n = 18) 33% Sober patients (n = 18) 78% Note: Low score is defined using the 10th percentile as a cutoff. Source: Dr. Lange ELSEVIER GLOBAL MEDICAL NEWS Note: Table made from bar graph.