Just for the sake of clarity, Alzheimer's is a specific disease, while dementia is a symptom that can have multiple causes.

I have to dispute Kenny's statement above that this disease is much more difficult for the relatives than the sufferers; It has been my personal experience that the sufferers know there is something wrong.
I found this on the web broken into stages of the disease:

Middle Stage Symptoms:

•Difficult behaviors emerge
•Anger, suspiciousness, overreacting and paranoia
•Repeating questions or statements
•Fear of bathing, Hallucinations, Eating problems
•Hoarding belongings
•Inappropriate sexual behavior
•Violent behavior
•Help in choosing clothes ,remembering to change clothes, help getting dressed.
•Will progress from needing reminders regarding personal care to needing help bathing, taking medication, brushing teeth, toileting, etc.
•Increased difficulty in verbal expression and comprehension
•Spatial problems (e.g., having trouble setting the table)
•Loss of reading, writing and arithmetic abilities
•Loss of coordination
•Will need care or supervision 24 hours a day, seven days a week
•May not recognize family and friends at times


Late Stage Symptoms:

•Inability to communicate
•Inability to recognize people, places and objects
•Loses ability to walk
•Loses ability to smile
•Muscles may become contracted
•May lose ability to swallow
•Seizures may occur
•Weight loss
•Majority of time spent sleeping
•May exhibit a need to suck on items

My mother developled dementia and became a whole different person, in a positive way. The mean-spirited, bitter woman I knew became someone who actually laughed and smiled - something I never saw growing up. My grandmother had Alzheimer's and went after her own daughter with a knife and was prone to other violent outbursts...