No single test, such as a blood test, can be used to diagnose a frontotemporal disorder. A definitive diagnosis can be confirmed only by a genetic test in familial cases or a brain autopsy after a person dies. To diagnose  a probable frontotemporal disorder in a living person, a doctor—usually a neurologist, psychiatrist, or psychologist—will:
Different types of brain imaging may be used. A magnetic resonance imaging (MRI) scan shows changes in the size and shape of the brain, including the frontal and temporal lobes. It may reveal other potentially treatable causes of the person’s symptoms, such as a stroke or tumor. In the early stage of disease, the MRI may appear normal. In this case, other types of imaging, such as positron emission tomography (PET) or single photon emission computed tomography (SPECT), may be useful. PET and SPECT scans measure activity in the brain by monitoring blood flow, glucose usage, and oxygen usage. Other PET scans can help rule out a diagnosis of Alzheimer's.
Is it depression?
Ana’s husband was the first to notice a change in his 55-year-old wife’s personality. Normally active in her community, she became less interested in her volunteer activities. She wanted to stay home, did not initiate conversations, and went on her daily walks only if her husband suggested it. Ana’s family thought she might be depressed . A psychologist recognized that her cognition was impaired and referred her to a neurologist, who diagnosed bvFTD.
Frontotemporal disorders can be hard to diagnose because their symptoms —changes in personality and behavior and difficulties with speech and movement—are similar to those of other conditions. For example, bvFTD is sometimes misdiagnosed as a mood disorder, such as depression, or as a stroke, especially when there are speech or movement problems. To make matters more confusing, a person can have both a frontotemporal disorder and another type of dementia such as Alzheimer's disease . Also, since these disorders are rare, physicians may be unfamiliar with the relevant symptoms and signs.
Can’t find the right words
Ray, 60, was a small-town minister, a quiet intellectual, and a poet. He had always been thoughtful and well spoken, but over time his weekly sermons became halting and confused. He had trouble finding the right words and resorted to gestures. His family doctor thought that Ray had had a stroke . But when tests showed no stroke, she referred Ray to a university medical center, where specialists diagnosed logopenic PPA.
Getting the wrong diagnosis can be frustrating. Without knowing their true condition, people with frontotemporal disorders may not get appropriate treatment  to manage their symptoms. Families may not get the help they need. People lose valuable time needed to plan treatment and future care. The medical centers listed in Resources  are places where people with frontotemporal disorders can be diagnosed and treated.
Researchers are studying ways to diagnose frontotemporal disorders earlier and more accurately. One area of research involves biomarkers, such as proteins or other substances in the blood or cerebrospinal fluid, which can be used to measure the progress of disease or the effects of treatment. Also being studied are ways to improve brain imaging, including seeing the tau protein, and neuropsychological testing, which assesses learning, language, problem solving, memory, and other thinking skills.