1. Apolipoprotein E gene (ApoE) is the most important genetic factor for Alzheimer disease (AD) and an important genetic factor for outcome of brain injury situations.
2. Function magnetic resonance imaging (fMRI) is a powerful tool for study of both brain regional functions and brain network.
3. Study about genetic contribution on fMRI is an emerging concept, which will help on understanding about how the genetics affecting the brain function.

There are about 4-10% people aged and over 65 years suffering from dementia in Taiwan. Dementia caused by diverse diseases, including Alzheimer's disease (AD), fronto-temporal dementia (FTD), dementia with Lewy body (DLB), Parkinson's disease dementia (PDD) and vascular dementia (VaD), is a neurodegenerative disease characterized by memory impairment, cognitive dysfunctions, behavioral disturbances and various kinds of psychiatric manifestations. AD is the most common cause of dementia in the world. Although the real pathophysiology of AD is still obscure, the compelling evidence has shown genetic factor should play an important role in the occurrence of AD. There are three genes, in terms of amyloid precursor protein (APP), presenilin-1 (PS1) and presenilin-2 (PS2), linked in the familial AD. Mutations on these genes would result in familial AD, which account for only less than 5% of AD. The only one well-documented genetic risk factor for sporadic AD is apolipoprotein E, ε4 allele (ApoE4). ApoE gene contains three genetic polymorphisms, ε2, 3, 4 and ApoE4 has been found associated with many brain injury situations, such as poor outcome for traumatic brain injury (TBI), Parkinson disease dementia (PDD). These findings might support ApoE to be important for brain functions but the real mechanisms remain further clarification. Functional magnetic resonance imaging (fMRI) is a powerful tool for study of both brain regional functions and brain network. To our knowledge, only few reports in top journals indicated genetic background is an important contributor for fMRI presentations. This could be a new filed of neuroscience. In this study, we will explore whether ApoE genetic polymorphisms affect the presentation of fMRI and realize some functions of ApoE in the brain. In addition, our data could enhance the new concept about the association between genetics and brain function.

Inclusion Criteria:

• people aged 45-65 years without cognitive impairment

Exclusion Criteria:

• unable to take APOE genotyping or undergo functional MRI

people aged 45-65 years taking health examination in TMU SHH no cognitive impairment by MMSE and AD8 screening