Everybody forgets things now and then, and even healthy people over 45 are more forgetful than younger folks.
What kind of forgetting points to something wrong?
Let's say your spouse goes to the supermarket to buy five items. Forgetting one or two of them would not be unusual. Even forgetting all five might not be so unusual if he or she were particularly distracted.
But if your spouse returns home and doesn't even remember going to the supermarket or gets lost on the way home, a serious problem might be indicated.
In the progressive deterioration of Alzheimer's disease, there are predictable stages of decline in mental, cognitive and other functions. But it's also important to keep in mind that other organic diseases, such as Parkinson's or multiple small strokes, cause some similar symptoms.
Also, before any diagnosis of Alzheimer's can be made, it is important to rule out anything else that might cause dementia-like effects in a patient.
Certain drugs, as well as drug interactions, drug overdoses and some toxic substances, can cause such effects.
And after all other organic causes of memory loss have been ruled out, the possibility of functional psychiatric illness should be considered, particularly because many forms of psychiatric illnesses are treatable.
In older people, for example, depression can be easily confused with dementia, especially if symptoms include inattentiveness to dress and grooming or if they interfere with communication.
Incidentally, almost any medication has, at some point, been reported to cause disruption in memory or concentration or to cause confusion.