Despite decades and nearly two dozen studies on dehydration in the frail elderly, very little conclusive evidence exists on its causes or solutions, a research team reported Wednesday in the Annals of Long-Term Care.

After their systematic review of 23 published research studies on the risk among those 65 and older, Diane Bunn, MSc, and colleagues said they could not identify “any proven effective strategies for dehydration prevention and/or increasing fluid intake for the older person living in long-term care facilities due to the high risk of bias in the studies reviewed.”

Elderly individuals are at a much greater and faster dehydration risk because their bodies generally have significantly lower water content (about seven liters less for a 150-pound person) than younger people, according to the Illinois Council on Long-Term Care.

Bunn’s research noted that while insufficient fluid intake can lead to needless suffering and increased costs, seemingly “simple solutions” continue to evade caregivers. Major impediments include co-morbidities and multiple physiological changes in the elderly. Bunn and colleagues also noted many intervention strategies that point to positive steps like increased choice of fluids, staff awareness and caregiver assistance also fail because they ignore these and other kinds of barriers.

A Commonwealth Fund study notes that at least one-third of the 1.6 million nursing home residents in the United States may suffer from malnutrition or dehydration, conditions that can aggravate or cause more severe medical problems such as tooth decay, broken bones, anemia, and low blood pressure — or in some cases even death.