1. The abnormal absence of thirst: Adrian was told that his lack of a desire to drink fluids, even when his body was low on water, was diagnosed as adipsia which was a result of an excess amount of salt in his body.
2. An abnormal avoidance of drinking: As people age, they have a tendency to have adipsia and so they are less likely to notice their thirst and may not drink sufficient fluids when they are needed.