Abstract

Introduction: Alzheimer’s disease remains a major cause of morbidity, mortality and dependency in older patients with dementia. With increasing age in older population and dementia in western hemisphere, an inexpensive and unified modality for early diagnosis of AD is of utmost importance.
Methods: We sought to investigate single photon emission computed tomography (SPECT) imaging of the brain as a less expensive modality in a prospective single blinded study in a cohort with diagnosis of probable Alzheimer’s dementia. Patients’ demographics, family history, Mini Mental Status Exam, brain imaging, biomarkers such as Tau, Amyloid beta protein, and Apo E genotype were obtained and analyzed. We tested different possible correlations models for association of current diagnosis of Alzheimer’s disease with SPECT and biomarkers using Chi-square test.
Results: Biochemical markers (Amyloid beta 42 and tau protein) have higher sensitivity in identifying patients with AD. APOE genotype is less sensitive as a diagnostic test. SPECT did not correlate with biomarkers in early AD, but showed higher correlation in moderate and severe dementia. Further investigation is warranted to identify a more sensitive and specific yet inexpensive testing for early diagnosis of AD.
Discussion: Biochemical and genetic markers have a closer association with each other and with Alzheimer’s compared to their association with brain imaging of patients with Alzheimer’s disease.

Keywords: Alzheimer’s disease; SPECT scan; Tau protein; Aß42 protein; Apo E genotype; Mini mental status evaluation; Family history