Dementia impairs memory, critical thinking, and decision-making. Alzheimer’s disease is caused by extracellular amyloid fibrils containing the peptide Amyloid beta (Aβ) accumulating in the brain. Alzheimer’s disease is the most common form of dementia. A slew of small molecule inhibitors developed over several decades has targeted dementia and related diseases. The drugs and inhibitors cannot cross the BBB due to their insurmountable nature. Many molecular nanomedicines have been developed that can cross the BBB via adsorptive-mediated transcytosis. Drug-loaded nanosized formulations, such as polymeric nanoparticles, solid lipid nanotransporters, liposomes, nanoemulsions, exosomes, gold nanoparticles, and dendrimers, have a significant impact on dementia diagnosis and treatment. This review focuses on recent developments in nanotechnology-based drug delivery systems for dementia and related disorders such as Alzheimer’s disease. Recent advances in nanotechnology may help overcome drug delivery limitations for dementia therapy. Nanoparticles' size, composition, and structural variety bring up new therapeutic possibilities, including treating and diagnosing neurodegenerative diseases. It is possible to enhance therapeutic effectiveness by enhancing pharmacokinetics, bioavailability, water solubility, and stability under physiological conditions while reducing adverse effects by restricting their location in healthy tissues.