Arachidonic acid (ARA) is one the two main polyunsaturated fatty acids (PUFAs) in the brain, especially in neuronal cells, and can be a target in the fight against the major public health concern represented by Alzheimer's disease (AD) and related disorders in high- as well as in low-income countries where elders constitute a growing part of the population. This compilation includes topics such as the use of arachidonic acid to prevent Alzheimer's disease, the dietary effects and sources of ARA, the effect of ARA on key oncogenic pathways in prostate cancer, and the effects of adipokines on prostaglandin E2 production by rheumatoid synovial fibroblasts.