Complete blood count and systemic inflammation indices in individuals with Alzheimer's disease: A case-control study

Alzheimer's disease (AD) is the most common cause of dementia, characterized by progressive cognitive and functional decline and is associated with aging. Chronic inflammatory processes are also involved in its the etiology, as the consequence or cause of proteinopathy (amyloid and tau load in the brain). This study aimed to investigate the complete blood count and systemic inflammation indices in 61 individuals with AD, compared to 59 cognitively healthy individuals as controls. The diagnosis of AD dementia was based on the NIA-AA criteria and patients presented biomarkers in the cerebrospinal fluid compatible with the diagnosis of AD. The complete blood count (CBC) was conducted using an automated system. The neutrophil count (p = 0.011), neutrophil-tolymphocyte ratio (p = 0.023), and Systemic Inflammation Response Index (SIRI) (p = 0.044) were significantly higher, whereas the lymphocyte count (p = 0.018) and platelet count (p = 0.038) were significantly lower in the AD group compared to the control group. After a multivariate generalized linear model analyses, neutrophils count and SIRI maintained significant difference between the groups, even after correcting for age, sex, body mass index and ApoE epsilon 4 carrier status. The overall results suggest that AD is associated with a low-grade proinflammatory profile, characterized by alterations in blood inflammatory and immune cells, leading to a higher systemic inflammatory index. The CBC and its derived inflammatory indices, routinely obtained in clinical practice, have potential utility in the context of AD.