**6. Brain Nanomedicine and Microglia**

The DHA used in clinical studies comes from either oil, algae, or industry. In the OmegAD study, the DHA came from Pronova Biocare. This company uses a process to deodorize its EPAX triglyceride oils, inducing neither taste nor odor. They use enzymes to form the triglycerides. Their product can be in the form of chewable capsules or a liquid formula. In these different possibilities, DHA is not targeted to a cerebral distribution. DHA is delivered systemically, and authors have observed changes at the plasma, cerebrospinal fluid, and cognitive levels [49,52]. It might be interesting to look at targeting DHA to the brain by using nanotechnology-based drug delivery systems to counteract the low penetration efficiency of drugs to the central nervous system due to the presence of the BBB. Two possibilities exist to reach the brain: either a direct passage that will damage the BBB, or an indirect passage via nanomedicines targeting the brain either orally or by nasal delivery through a spray. The results presented in this section will focus on those obtained on microglia, whether from primary culture, lineages, or animal models, in the context of neurodegenerative diseases.
