What Causes Short Term Memory Loss And Severe Depression?

My mother is 78 years old. In the last year and a half she has had a serious design in cognitive behavior. She is a retired school principal who, up until this, was active, organized and intelligent. She did, however, drink consistently for as long as I can remember. On most nights she would have 3-4 drinks. She started to have some lapses in short term memory and would often ask the same question several times. Her primary physician started to prescribe medication for this as well as for depression. (She had started having crying spells) She cut down significantly on drinking, but her cognition got worse. She was often unable to interpret her environment. This came on quickly. She was admitted to the hospital for a few days where no tests or real observations were done, but medications were added and she was diagnosed with Alzheimer’s. The medications started building up —- at this point she was on 16 different things including antidepressants, benzodiazepine, and Alzheimer’s medication. She is only seeing a primary physician and psychiatric nurse practitioner regularly. We did have an appointment with a neurologist who read her brain scan and said he only saw typical signs of aging— no shrinkage. While some meds have been discontinued, she is still on several, including the benzo. My step dad is taking care of her with some assistance from home health care. She often goes from being calm with some clarity to excessive crying and possible hallucinations throughout the day. She seems to get better, then regress. She is worse when she has a UTI, but even when clear, she is in somewhat of a state of delirium most of the time. I feel like no one is looking at the big picture with her. Is it possible that the doctors jumped to the Alzheimer’s diagnosis too quickly? Could medication be causing any of this?