Alzheimer’s Genetic Risk Score linked to Incident Mild Behavioral Impairment

Abstract

Mild Behavioral Impairment (MBI) describes the emergence of later-life Neuropsychiatric Symptoms (NPS) as an at-risk state for cognitive decline and dementia and as a potential manifestation of prodromal dementia. How NPS mechanistically link to the development of Mild Cognitive Impairment (MCI) and Alzheimers disease (AD) is not fully understood. Potential mechanisms include either shared risk factors that are related to both NPS and cognitive impairment, or AD pathology promoting NPS. This is the first study to examine whether AD genetic loci, individually and as a genetic risk score, are a shared risk factor with MBI. 1377 older adults (aged 72-79; 738 males; 763 normal cognition) from the PATH Through Life project. MBI was assessed in accordance with Criterion 1 of the ISTAART-AA diagnostic criteria using the Neuropsychiatric Inventory. 25 LOAD risk loci were genotyped and a weighted genetic risk score (GRS) was constructed. Binomial logistic regression adjusting for age, gender, and education examined the association between LOAD GRS and MBI domains. An increase in the LOAD GRS and APOE*{varepsilon}4 were associated with higher likelihood of Affective Dysregulation; MS4A4A-rs4938933*C and MS4A6A-rs610932*G were associated with a reduced likelihood of Affective Dysregulation; ZCWPW1-rs1476679*C was associated with a reduced likelihood of Social Inappropriateness and Abnormal Perception; BIN1-rs744373*G and EPHA1-rs11767557*C were associated with higher likelihood of Abnormal Perception; NME8-rs2718058*G was associated with a reduced likelihood Decreased Motivation. These findings suggest a common genetic etiology between MBI and traditionally recognized memory problems observed in AD and improve our understanding of the pathophysiological features underlying MBI.