Dementia can be diagnosed with a battery of tests

Q: How is one screened for/diagnosed with Alzheimer's or other forms of dementia? What type of doctors does one see? What sorts of tests do they run? It runs in my family, and lately I've been forgetting conversations soon after they happen. But I don't know where to look for answers.

A: Your concern is understandable. The degeneration of the brain's ability to incorporate new information - and the loss of the hardwiring that controls our everyday tasks - affect not only an individual, but everyone who cares for that person as well.

Further, the genetic linkage is greatest for people with a parent or sibling who developed dementia prior to the age of 65. (The linkage grows progressively weaker with the family member's age of diagnosis, so much so that if the person was diagnosed after 85, one's own risk is no different than if there were no family history.)

Further, the rates of dementia are increasing in this country, with Alzheimer's dementia affecting 5.4 million people in the United States in 2016. Some of this may be due to our ability to diagnose the disease, but our increasing rates of risk factors - diabetes, obesity and lack of physical activity - play a role as well. The majority of people are diagnosed after the age of 65, with the overall incidence of dementia doubling every 10 years after the age of 60.

Diagnosis typically starts with your primary care doctor. While blood tests can pick up some non-Alzheimer's causes for memory loss, such as B12 deficiency, the standard screening exam is the Mini-Mental Status Examination (MMSE), a memory and writing test. That said, another test, the Montreal Cognitive Assessment (MoCA), has greater sensitivity in identifying losses in the abilities to use language and perform tasks - both common markers for encroaching dementia - so your doctor may use this as well.

These tests can effectively identify people who already have dementia, but they are less effective at identifying people in the early stages of memory loss or those who have memory loss but also have a higher level of brain function.

In these cases, much longer and more formal neuropsychological tests may be necessary. This testing is often done by a psychologist associated with a neurologist.

A neurologist may also order imaging tests of the brain. These tests can include an MRI, positron emission tomography (a PET scan) and possibly functional brain imaging that assesses areas of the brain with low activity. Although some findings might suggest Alzheimer's, these tests are used primarily to rule out other causes; they can't yield a definitive Alzheimer's diagnosis.

The potential to use cerebrospinal fluid biomarkers to help diagnose Alzheimer's disease is still in the investigational phase and unlikely to be used by a neurologist currently.

So start by talking to your primary care doctor about the change in your memory, how long it's been happening and whether it's rapidly getting worse.

Your doctor will likely conduct a standardized test for memory, along with blood work to rule out other causes of memory loss. If that suggests a problem, but no other physical cause, you should see a neurologist for more formal testing.

• Robert Ashley, M.D., is an internist and assistant professor of medicine at the University of California, Los Angeles. Send your questions to askthedoctors@mednet.ucla.edu.