Therefore, based on the first two steps used in diagnosing patients, this patient does have a dementia. A slow progression would be typical for Alzheimer's disease. After the history and examination, this hypothetical patient has an MRI (a test that shows normal and abnormal features of the brain). The report of this test indicates that the MRI shows evidence of more than one stroke. In the setting of a previous heart attack (a disorder that is known to commonly be associated with stroke), the MRI result might make a clinician believe that the patient has dementia because of stroke, so called "vascular dementia."
At this point there is conflicting evidence. Does the patient have Alzheimer's disease, vascular dementia, or both? It is not possible to answer this question. Consequently, physicians of equal background and ability may arrive at different diagnoses, even when they are in total agreement on the available information, both from the patient and from the available research studies.
In summary this blog and my most recent blog before this one have attempted to illustrate a fundamental issue in medicine. It is not an exact science. The field of medicine knows much about people and the diseases that affect them. However, no clinician can have all of this knowledge. Even if a clinician does, there are still major gaps in our knowledge. This makes the field an inexact science. In this setting, it is quite possible for two clinicians to arrive at different conclusions about a diagnosis of Alzheimer's disease.
