Alternative Causes of Dementia
In attempting to make a diagnosis of Alzheimer's disease, the doctor will be considering alternative causes of dementia. For example, if a child, teenager or young adult has features of dementia, as described above, Alzheimer's disease is very unlikely. Therefore, the causes of dementia in a young person would be considered. Another setting of dementia that is not Alzheimer's disease would be someone who has dementia after a head injury. In an older person, the presence of a head injury does not exclude the possibility of Alzheimer's disease as well. However, any young person who was normal before a head injury and who had dementia after a head injury would be diagnosed with "post-traumatic (after injury) dementia."
Distinguishing Alzheimer's disease from other late-life causes of dementia is not as easy or as obvious as the examples given above. In fact, even the doctors most knowledgeable about Alzheimer's disease are not always accurate in making the diagnosis.
Parkinson's Disease with Dementia vs. Alzheimer's Disease with Dementia
There is a list of other forms of dementia that can occur in later life. Distinguishing some of these from Alzheimer's disease may be important. For example, the treatment of Parkinson's disease with dementia is different from the treatment of Alzheimer's disease, because there are specific treatments for the problems of movement seen in patients with Parkinson's disease.
Therefore, one of the goals of the doctor is to distinguish disorders that have different treatments and attempt to use that treatment most appropriate for that individual person. Another goal that the doctor has is to have enough information about the dementia to appropriately counsel the patient and family members about the diagnosis and treatment plan.
In summary, Alzheimer's disease is, by definition, a type of dementia. However, a diagnosis of dementia does not always mean that the person with that diagnosis has Alzheimer's disease. Sometimes these distinctions are easy, and sometimes they are not.
To learn more about Alzheimer's and dementia diagnosis, treatment, and prevention, check out Alzheimer's Basics.
