Acute confusional states and dementia in the elderly: the role of dehydration/volume depletion, physical illness and age.

A prospective study was undertaken to investigate the incidence and aetiology of acute confusional states in physically ill old people. The subjects were 71 patients aged 70 years or over who were admitted as emergencies to a general medical unit. Mental testing revealed that: (a) one in six patients had an acute confusional state on admission; and (b) one in four patients had evidence of dementia. The presence of dehydration/volume depletion at the time of admission was estimated by various parameters which were brought together to form a new index called the 'dehydration score'. There was a definite statistical association between high degrees of dehydration/volume depletion and poor mental function. Advanced age, on the other hand, appeared to increase the risk of dehydration/volume depletion only slightly. It was also found that a patient's mental score was a much better guide to prognosis than age. The implications of these findings are discussed.