“Is Alzheimer's diagnosed with a blood test?”

My father died of Alzheimer's disease so I feel for you here, and hope for the best.

To best diagnose Alzheimer's disease, the best test is a functional test of your brain, the neuropsychiatric exam. It is a 2-day test of concentration, memory, problem-solving and spacial dimension. It can distinguish between fine shades of the dementias versus brain injury. Your PCP can order it, and it is usually given by a technician, so that seeing a neurology consultation is also in order.

First of all, you need to understand that there are several classifications of Dementia ( It is a group of symptoms that affect your ability think or reason clearly) The most common one is 1. Reversible Dementias: here we add all Dementias that have a medical treatment, once we determine what is causing it. For instance Thyroid problems, can mimic dementia symptoms, once you treat the problem the dementia symptoms reverse. Another Example is Vitamin B12 Deficiency once you treat the deficiency the memory problems disappears. In this cases, yes; there are blood tests that can help defining the etiology of the Memory loss. The second group of Dementia is what we call Irreversible Dementias: where there is not cure for the disease. Of course there are medications that can slow down the progression of the disease but can not cure it. In this group is where Alzheimer's Disease falls. Alzheimer dementia is the most common form of dementia, accounting for up to 60-80% of cases. For the diagnosis os Alzheimer to be made it takes a long time and usually involves a series of tests including questionnaires and brain scans.

Best bet is to let a neurologist do other tests. Because of your youth, it may be something entirely different.