What is the difference between Alzheimer’s disease and dementia? Dr. Gayatri Devi, board-certified neurologist and author of The Spectrum of Hope: An Optimistic and New Approach to Alzheimer’s Disease, explains that dementia is an umbrella term for the death of nerve cells and loss of brain function, while Alzheimer’s disease is a specific type of dementia. Diagnosing the type of dementia, by collecting spinal fluid, is critical in determining treatment options.