Examination of the influence of cedar fragrance on cognitive function and behavioral and psychological symptoms of dementia in Alzheimer type dementia

Neuropsychopharmacol Rep. 2020 Mar;40(1):10-15. doi: 10.1002/npr2.12096. Epub 2020 Feb 9.


We examined whether symptoms of dementia are improved by olfactory nerve stimulation in Alzheimer type dementia patients. First, a stick-type olfactory identification ability test was performed in patients with Alzheimer type dementia, to select patients without olfactory dysfunctions. Then, these patients were randomly assigned into the intervention (n = 19) and the control groups (n = 17). To evaluate the effects of olfactory nerve stimulation, we exposed the intervention group to a disinfecting ethanol with added aroma extracts from ceder and the control group to the ethanol without the added aroma extracts. Each group underwent the intervention for 8 weeks, cognitive and behavioral functions were evaluated before and after treatments using the Neuropsychiatric Inventory (NPI), the Japanese version of Zarit Caregiver Burden interview (J-ZBI), and the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog). A significant improvement was observed in the NPI score and J-ZBI in the intervention group compared to the control group at 4 and 8 weeks. On the other hand, there was no significant difference in the score of ADAS-cog. Exposure to cedar fragrance improved behavioral and psychological symptoms of dementia (BPSD) in Alzheimer type dementia and may reduce the burden of nursing care. In addition to its effectiveness, the procedure is simple and minimally invasive and would be a valuable non-pharmaceutical treatment.

Keywords: alzheimer type dementia; aroma extracts from ceder; cognitive disorders; cognitive neuoscience; dementia; olfactory nerve.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Administration, Inhalation
  • Aged
  • Aged, 80 and over
  • Alzheimer Disease / complications
  • Alzheimer Disease / physiopathology
  • Alzheimer Disease / psychology
  • Alzheimer Disease / therapy*
  • Aromatherapy / methods*
  • Behavioral Symptoms / etiology
  • Behavioral Symptoms / physiopathology
  • Behavioral Symptoms / psychology
  • Behavioral Symptoms / therapy*
  • Ethanol / administration & dosage
  • Female
  • Humans
  • Male
  • Oils, Volatile / administration & dosage*
  • Olfactory Nerve* / drug effects
  • Olfactory Perception* / drug effects
  • Solvents / administration & dosage


  • Oils, Volatile
  • Solvents
  • Ethanol
  • cedarwood oil