The disease is known to target the hippocampus which is associated with memory, and this is responsible for the first symptoms of memory impairment. As the disease progresses so does the degree of memory impairment. First symptoms
The first symptoms are often mistakenly attributed to aging or stress. Detailed neuropsychological testing can reveal mild cognitive difficulties up to eight years before a person fulfills the clinical criteria for diagnosis of Alzheimers disease. These early symptoms can affect the most complex activities of daily living. The most noticeable deficit is short term memory loss, which shows up as difficulty in remembering recently learned facts and inability to acquire new information.Subtle problems with the executive functions of attentiveness, planning, flexibility, and abstract thinking, or impairments in semantic memory (memory of meanings, and concept relationships) can also be symptomatic of the early stages of Alzheimers disease. Apathy and depression can be seen at this stage, with apathy remaining as the most persistent symptom throughout the course of the disease. Mild cognitive impairment (MCI) is often found to be a transitional stage between normal aging and dementia. MCI can present with a variety of symptoms, and when memory loss is the predominant symptom, it is termed amnestic MCI and is frequently seen as a prodromal stage of Alzheimers disease. Amnestic MCI has a greater than 90% likelihood of being associated with Alzheimers. Early stage
In people with Alzheimers disease, the increasing impairment of learning and memory eventually leads to a definitive diagnosis.
These tests may not always be accurate, as they lack sensitivity to mild cognitive impairment, and can be biased by language or attention problems; more comprehensive test arrays are necessary for high reliability of results, particularly in the earliest stages of the disease.Further neurological examinations are crucial in the differential diagnosis of Alzheimers disease and other diseases. Interviews with family members are used in assessment; caregivers can supply important information on daily living abilities and on the decrease in the persons mental function. A caregivers viewpoint is particularly important, since a person with Alzheimers disease is commonly unaware of their deficits. Many times, families have difficulties in the detection of initial dementia symptoms and may not communicate accurate information to a physician.Supplemental testing can rule out other potentially treatable diagnoses and help avoid misdiagnoses. Common supplemental tests include blood tests, thyroid function tests, as well as tests to assess vitamin B12 levels, rule out neurosyphilis and rule out metabolic problems (including tests for kidney function, electrolyte levels and for diabetes). MRI or CT scans might also be used to rule out other potential causes of the symptoms – including tumors or strokes.