Role of Imaging Genetics in Alzheimer's Disease: A Systematic Review and Current Update.

ABSTRACT

BACKGROUND: Alzheimer's disease is a neurodegenerative disorder characterized by severe cognitive, behavioral, and psychological symptoms, such as dementia, cognitive decline, apathy, and depression. There are no accurate methods to diagnose the disease or proper therapeutic interventions to treat AD. Therefore, there is a need for novel diagnostic methods and markers to identify AD efficiently before its onset. Recently, there has been a rise in the use of imaging techniques like Magnetic Resonance Imaging (MRI) and functional Magnetic Resonance Imaging (fMRI) as diagnostic approaches in detecting the structural and functional changes in the brain, which help in the early and accurate diagnosis of AD. In addition, these changes in the brain have been reported to be affected by variations in genes involved in different pathways involved in the pathophysiology of AD. METHODOLOGY: A literature review was carried out to identify studies that reported the association of genetic variants with structural and functional changes in the brain in AD patients. Databases like PubMed, Google Scholar, and Web of Science were accessed to retrieve relevant studies. Keywords like 'fMRI', 'Alzheimer's', 'SNP', and 'imaging' were used, and the studies were screened using different inclusion and exclusion criteria. RESULTS: 15 studies that found an association of genetic variations with structural and functional changes in the brain were retrieved from the literature. Based on this, 33 genes were identified to play a role in the development of disease. These genes were mainly involved in neurogenesis, cell proliferation, neural differentiation, inflammation and apoptosis. Few genes like FAS, TOM40, APOE, TRIB3 and SIRT1 were found to have a high association with AD. In addition, other genes that could be potential candidates were also identified. CONCLUSION: Imaging genetics is a powerful tool in diagnosing and predicting AD and has the potential to identify genetic biomarkers and endophenotypes associated with the development of the disorder.