Memory loss in itself is not a sign of Alzheimer's disease. Most people normally have some memory loss as they age. In Alzheimer's disease, the problem will worsen steadily. Although symptoms may seem to come on quite quickly, the problem often builds very slowly. Many times the symptoms are first noticed after the person has been under some strain.
Depression is one of the more common symptoms in the early stage of the disease.
The signs of depression may include seeming sadder, quieter or more negative than usual, sleeping too much or too little, losing an unusual amount of weight, drinking more than usual or not seeming aware of or interested in things. The forgetful person may also feel frightened, ashamed or just plain bewildered by the changes. As a result, even those people closest to the impaired person may need a fairly long period of time, even years, to realize that something is really wrong. As soon as the problem is noticed, however, the forgetful person should be seen by a doctor who knows about dementia. A firm diagnosis of Alzheimer's disease is not yet possible in this stage of the disease.