APOE and Alzheimer disease: This study assessed whether the levels of cerebrospinal fluid (CSF) AD biomarkers, scores on neuropsychological tests, and genetic biomarkers of AD (apolipoprotein E (APOE) haplotype) differ between AD patients with various 5HTR1B rs13212041, 5HTR2A rs6313 (T102C), 5HTR2C rs3813929 (−759C/T), and 5HTR6 rs1805054 (C267T) polymorphisms.