β-amyloid disrupts human NREM slow waves and related hippocampus-dependent memory consolidation

Independent evidence associates beta-amyloid pathology with both non-rapid eye movement (NREM) sleep disruption and memory impairment in older adults. However, whether the influence of beta-amyloid pathology on hippocampus-dependent memory is, in part, driven by impairments of NREM slow wave activity (SWA) and associated overnight memory consolidation is unknown. Here we show that beta-amyloid burden in medial prefrontal cortex (mPFC) correlates significantly with the severity of impairment in NREM SWA generation. Moreover, reduced NREM SWA generation was further associated with impaired overnight memory consolidation and impoverished hippocampal-neocortical memory transformation. Furthermore, structural equation models revealed that the association between mPFC beta-amyloid pathology and impaired hippocampus-dependent memory consolidation was not direct, but instead statistically depended on the intermediary factor of diminished NREM SWA. By linking beta-amyloid pathology with impaired NREM SWA, these data implicate sleep disruption as a mechanistic pathway through which beta-amyloid pathology may contribute to hippocampus-dependent cognitive decline in the elderly.