Genetic and molecular studies have confirmed the central role of amyloid‐β production and fibrillation in the pathogenesis of Alzheimer's disease (AD). However, the pathological pathways from amyloid‐β peptide oligomerization to the major pathological hallmarks of AD, such as neurofibrillary tangles, inflammation and loss of cholinergic neurons, are largely unknown. The innate immunity defence system utilizes pattern recognition receptors to respond to a variety of danger‐ and pathogen‐associated molecular structures. Amyloid‐β oligomers and fibrils and their cellular effects can activate the innate immunity defence and induce inflammatory and apoptotic responses in human brain. Amyloid‐β oligomers can interfere with many aspects of neuronal membrane functions and can evoke potassium (K⁺) efflux from neurons. A low K⁺ concentration is a potent activator for the NALP1 inflammasomes, which then stimulate caspase‐1 to cleave the proforms of IL‐1β and IL‐18 cytokines. Interestingly, recent observations have demonstrated that amyloid‐β fibrils can activate NALP3 inflammasomes Via the lysosomal damage in mouse microglia. We will review here the activation mechanisms of NALP inflammasomes in neurons and microglia and several downstream effects in brain demonstrating that toxic amyloid‐β oligomers and fibrils can light afire in inflammasomes and induce Alzheimer's pathology.