Loss of smell may signal future illnesses. A decreased sense of smell may be an early sign of Alzheimer’s or Parkinson’s disease.
Two studies presented at the Alzheimer’s Association International Conference 2014 found that a reduced ability to identify scents was associated with brain cell function loss and advancement to Alzheimer’s disease.
A study published in the Annals of Neurology also found that a weakened sense of smell can precede the development of Parkinson's.