Environmental Effects on Brain Function

Abstract

Environmental extremes can result in local and systemic illness, or even death. A majority of cases involving environmental mishap are related to excessive heat, cold, or high altitude exposure. Heat- or cold-related illness occurs when the body's homeostatic mechanisms are overwhelmed, resulting in an accumulation or loss of heat, respectively. Altitude illness results from a combination of low temperature and hypoxia. All three environmental injuries have significant effects upon brain function. This article discusses the pathophysiology of heat, cold, and altitude illness and their effects upon brain function.

The influence of hypoxia and prolonged exercise on attentional performance at high and extreme altitudes: A pilot study

“…The authors hypothesized that there would be an improvement in cognitive functions during exercise under severe hypoxia, but finally reported an attenuation of this improvement in individuals exhibiting a greater decrease in s p O 2 . One possible explanation for this unexpected finding in the present study and its inconsistency with previous study findings is that visual contrast sensitivity is particularly enhanced during acute, short-term hypoxia, as reported in earlier investigations [ 45 , 46 ]. The FAIR-2 test is based on visual discrimination of different test items.…”

“…Thus, hypoxia and sleep deprivation may both contribute to attentional deficits in mountaineers at high altitude. It has also been proposed that the relatively low temperatures at high altitude affect brain functions [ 46 ]. Attentional encoding processes are impaired when exposed to thermal stress (e.g., cold) [ 16 ].…”

Bed Rest and Cognition: Effects on Executive Functioning and Reaction Time

“…Crucially, the effects on the brain of extreme cold, heat, or altitude can produce cognitive defi cits that decrease the chances of surviving these conditions ( 8 ). Space is an environment with unique extremes.…”

Cognition-Enhancing Drugs and Their Appropriateness for Aviation and Ground Troops: A Meta-Analysis

“…A review of the literature failed to find studies examining the effects of cognitively enhancing drugs on environmental stressors like heat stress and dehydration. However, it is known that medications like beta-blockers often contribute to heatrelated illness as they impair heat reduction mechanisms (Finnoff, 2008), and pharmaceuticals can be profoundly affected by hydration levels.…”