Illness occasionally presents with mental confusion in people of all ages but in old age it is one of the commonest of all presenting symptoms. Professor Brocklehurst stresses the importance of a clear system of classification in diagnosing the cause

Mental confusion may mean impairment of memory which may be slight and hard to distinguish from the normal memory loss of advancing age, or it may be profound. It may involve disorientation so that the individual is unaware of his surroundings or of the time of day or month of the year.