The objective of this study is to demonstrate the cognitive enhancement effect and safety of Tremella Fuciformis, using the cognitive and clinical indicators (e.g. memory, attention, and psychomotor speed) and the latest brain imaging methods for healthy adults suffering subjective cognitive impairment.

Inclusion Criteria:

• Age between 40 and 65 years old
• Global Deterioration Scale score (GDS) of 2
• High school or higher levels of education.

Exclusion Criteria:

• Current pregnancy or breast-feeding
• Evidence of neurologic or medical conditions
• Axis I diagnosis when assessed by the board certified psychiatrist using the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorder, 4th edition (DSM-IV)(SCID-IV)
• Mini-mental status examination score of 24 or less
• Clinical Dementia Rating score of 0.5 or more suggesting cognitive impairment beyond self-perceived subjective deficits
• Intelligence quotient less than 70
• Contraindications to magnetic resonance imaging (MRI)
• Use of psychotropics in last 3 months
• Use of oral contraceptive medication
• Participation in other clinical trials during the study period that might affect the outcome of the present study
• Allergic adverse reactions to mushrooms