News article

The negative impacts of dehydration on cognitive performance

Posted:  Friday, November 16, 2012

Several scientific studies into the effects of dehydration on adults have highlighted how it can impair short and long-term memory, induce fatigue and lower cognitive performance – the extent of which depends on the intensity and speed of dehydration and fluid ingestion. Many of these studies can be downloaded from the NNI website, links to these documents can be found at the end of this summary.

In healthy global adults (women and men) global cognitive-motor performance is preserved during water deprivation up to a moderate dehydration level of 2.6% loss of body weight, when subjects are able to increase their task related effort. These findings, which were observed during slowly progressive dehydration, are in contrast to acute water loss due to exercise or heat (Szinnai et al 2005, Cian et al. 2001, Gopinathan et al. 1988). Cian et al. demonstrated that dehydration induced by heat stress or exercise can have detrimental effects on short-term memory, working memory and visuo-motor abilities. However, although no beneficial effect on cognitive variables could be demonstrated with fluid ingestion, it did prevent a decrement in long-term memory as compared to control and dehydration. (Cian et al. 2001) In a different study Cian et al showed that hyperhydration may improve short-term memory (Cian et al. 2000).
For more about these studies and their conclusions, please use the following links:

GOPINATHAN PM. et al, 1988: Role of dehydration in heat stress-induced variations in mental performance (read)

CIAN C. et al, 2000: Influence of Variations in Body Hydration on Cognitive Function: Effect of Hyperhydration, Heat Stress, and Exercise-Induced Dehydration (read)

CIAN C. et al, 2001: Effects of fluid ingestion on cognitive function after heat stress or exercise-induced dehydration (read)

SZINNAI G. et al, 2005: Effect of water deprivation on cognitive-motor performance in healthy men and women (read)

Other summaries in our hydration series:

Does having a drink, make you think? The effect of good hydration on children 
Promoting good hydration, promotes good health. The health benefits of hydration