This lecture covers the molecular and chemical basis of neurological disorders, focusing on Alzheimer's disease and anxiety. It delves into the morphological changes in the brain of Alzheimer's patients, the pathophysiology of amyloid plaques and neurofibrillary tangles, available therapies, such as acetylcholinesterase inhibitors and NMDA receptor antagonists, and the molecular basis of anxiety. Additionally, it discusses pain, analgesic agents, and the renin-angiotensin system. The development of aliskiren, the first renin inhibitor for clinical treatment, is also explored, along with the need for new blood pressure-lowering drugs and the clinical trials conducted post-approval.