Examination of the influence for cognitive function of aromatherapy using the essential oil which was extracted from Abies sachalinensis

INTERVENTION: In before and after using aromatherapy using the 100% essential oil which was extracted from Abies sachalinensis, we carry out test of cognitive function, olfactometry, questionnaires and blood tests. Subjects carry out the aromatherapy for two hours in the morning and two hours at night, and continue for four weeks In before and after using aromatherapy using the 30% essential oil which was extracted from Abies sachalinensis, we carry out test of cognitive function, olfactometry, questionnaires and blood tests. Subjects carry out the aromatherapy for two hours in the morning and two hours at night, and continue for four weeks CONDITION: Alzheimer's disease, mild cognitive impairment PRIMARY OUTCOME: The results of Touch Panel‐type Dementia Assessment Scale (TDAS) after four weeks SECONDARY OUTCOME: The results of Odor Stick Identification Test for the Japanese, questionnaire and blood tests after four weeks INCLUSION CRITERIA: 1) Subjects who are more than 40 years old at the time of registration 2) Alzheimer's disease patients who fulfill of the DSM‐5 and NINCDS‐ADRDA criteria, or mild cognitive impairment patients who fulfill of the Petersen criteria. 3) The consent from proxies is necessary. 4) If the patient use antidementia medicine, it is necessary that cognitive function is stable