Association Between CSF Beta-Amyloid and Apathy in Early-Stage Alzheimer Disease

The apathetic syndrome is a common clinical feature in patients with Alzheimer diseases (AD), from preclinical phases to late stages of dementia, and it is strongly related to major disease outcomes. Unfortunately, no specific pharmacological treatments for apathy have been accomplished so far. Translational evidences have previously shown that a link between apathy and hallmarks of AD-related pathophysiology, that is, β-amyloid (Aβ) plaques and neurofibrillary tangles, exists. However, only few studies investigated the association between core biomarkers of AD and apathy scores, finding conflicting results.

Thirty-seven patients were identified as having AD dementia according to National Institute on Aging-Alzheimer Association 2011 criteria. All participants underwent an extensive diagnostic workup including cerebrospinal fluid (CSF) assessment to measure the concentrations of Aβ₄₂, t-tau, and pTau_181. To follow, they were stratified as: apathy absence, apathy mild, and apathy severe according to the Neuro Psychiatric Inventory-apathy item scores. We investigated for potential associations between apathy scores and CSF biomarkers concentrations as well as for differences in terms of clinical and CSF biomarkers data across the 3 apathy groups.

The CSF Aβ₄₂ concentrations were negatively correlated with apathy scores. In addition, patients with severe apathy had significantly lower Aβ₄₂ levels compared to nonapathetic ones.

Based on our results, we encourage further studies to untangle the potential association between the complex pathophysiological dynamics of AD and apathy which may represent an innovative reliable clinical outcome measure to use in clinical trials, investigating treatments with either a symptomatic or a disease-modifying effect.