Gut Microbiome and Blood Indices in Patients with AD and Their Spousal Caregivers

Patients with Alzheimer's disease (AD) have gut dysbiosis. Short-chain fatty acids (SCFAs) are products of the gut microbiome. Among them, Acetate and valeric acid were positively correlated with the Aβ plaque load detected by amyloid PET in participants with or without AD. However, the levels of SCFAs in the blood of patients with AD have not been defined. Also, the usefulness of indices of inflammation and neuropathology in the blood as biomarkers for cognitive impairment in patients with AD is elusive. Importantly, spousal caregivers of patients with dementia have a higher risk of developing dementia later in life than those whose spouses do not have dementia. The spousal caregivers have an accelerated cognitive decline. The mechanisms for these phenomena are not known. We hypothesize that spousal caregivers of patients with AD have gut microbiome and levels of blood SCFAs similar to those of patients with AD, that these spouses have increased inflammatory cytokines and indices of AD-like neuropathology in the blood, and that there is a correlation between the cognition and various indices in the blood among patients with AD, their spouses, and age-matched controls. To address these hypotheses, we will recruit three groups of participants: Patients with AD, their spousal caregivers, and controls that are age-matched with the caregivers. Their gut microbiome and indices of neuroinflammation and neuropathology in the blood will be determined. Their cognition will be assessed. The correction of cognition with gut microbiome genera or indices in the blood will be analyzed. Our studies may represent the first study to determine whether the gut microbiome and SCFAs may play a role in the cognitive impairment in the spousal caregivers of patients with AD. These studies may also identify biomarkers for cognitive impairment in these caregivers and patients with AD. These findings may ultimately help the care of patients with AD and reduce the cognitive declines in spousal caregivers of patients with AD.