Inclusion Criteria:  ages >50 years with a diagnosis of mild or moderate dementia being admitted to the day care center and living in the community being willing to do blood test with a family member's consent.  Exclusion Criteria:  experience in chronic rhinitis or sinusitis, which causes loss of smell; inability to perform the cognitive exam or olfactory test (e.g., having a severe hearing impairment) inability to attend group activities due to severe emotional or aggressive behaviors