Neurodegenerative diseases like Alzheimer’s disease (AD) are poised to become a global health crisis, and therefore understanding the mechanisms underlying the pathogenesis is critical for the development of therapeutic strategies. Mutations in genes encoding presenilin occur in most familial Alzheimer’s disease but the role of PSEN in AD is not fully understood. In this review, the potential modes of pathogenesis of AD are discussed, focusing on calcium homeostasis and mitochondrial function. Moreover, research using Caenorhabditis elegans to explore the effects of calcium dysregulation due to presenilin mutations on mitochondrial function, oxidative stress and neurodegeneration is explored.