How do we diagnose FTD disorders?

OVERVIEW

As the symptoms of Frontotemporal degeneration (FTD) often first appear in a person’s 50’s or 60’s and can include dramatic changes in behavior and personality, it is not unusual for an individual to be referred to multiple specialists, such as a psychiatrist, before an accurate diagnosis is made.

To assess for Frontotemporal degeneration, Dr. Grossman and his clinical team gather a detailed medical history and complete a thorough neurological examination. This evaluation may also include:

Neuropsychological examination to assess language, behavior, memory, executive and visual-spatial functions.
Neuroimaging such as an MRI (magnetic resonance imaging) to determine where and how extensively brain regions have atrophied.
Blood tests and lumbar puncture to rule out other diseases that can mimic FTD.

BLOOD TESTS AND LUMBAR PUNCTURE TO RULE OUT OTHER DISEASES THAT CAN MIMIC FTD. THE DIAGNOSIS OF FRONTOTEMPORAL DEGENERATION (FTD) GENERALLY INVOLVES:

Medical history and detailed neurological examination.
Neuropsychological examination to assess language, behavior, memory, executive and visual-spatial functions.
Neuroimaging to determine where and how extensively brain regions have atrophied. Some of these neuroimaging studies are: MRI (magnetic resonance imaging), PET (positron emission tomography), and SPECT (single photon emission computed tomography).
Blood tests and lumbar puncture to rule out diseases that can mimic FTD.

TESTS USED IN THE DIAGNOSIS OF FRONTOTEMPORAL DEGENERATION

At present, there is no single diagnostic test that can confirm or rule out a diagnosis of FTD. There are many potential factors that can contribute to changes in cognition, behavior and motor skills. With each test examining these factors, additional information about the patient is obtained that will lead to a more accurate diagnosis. This information can be used by the physician to recommend treatment.

Below is a list of some of the tests that may be encountered during a diagnostic work-up, and a brief description of each of these tests.

Neurological exam: A detailed examination of the entire nervous system, including physical and cognitive functioning. An initial evaluation usually takes about an hour and includes:

Obtaining past medical history.
Physical examination– evaluating motor function such as walking, balance, coordination, reflexes, strength, as well as vision and hearing.
Cognitive examination– evaluating memory, language, thinking, planning and organizational skills, visuospatial abilities, behavior and mood.

Neurology is a complex field, and there are different specialties even among neurologists; therefore, it is not uncommon for an individual to see more than one neurologist. It is important for an individual to be evaluated by a neurologist experienced with FTD and related neurodegenerative conditions.

Neuropsychological testing: Pencil-and-paper tests and interviews that evaluate cognition and mood in order to identify specific areas of strength and weakness. Weaknesses often reflect brain areas that have reduced functioning. Tests assess memory, concentration, visuospatial, problem-solving, basic math and language skills. These tests take several hours to administer and are interpreted by a neuropsychologist. They can differentiate depression from dementia, and can help in the diagnosis of specific types of dementia or brain disorders. For example, someone with Alzheimer’s disease will show significant deficits in tests of memory while someone with FTD can do fairly well with memory but have more difficulty on measures of language and social skills.

Routine blood work: Tests for specific chemicals, proteins, hormones and antibodies to detect conditions that can mimic FTD, such as thyroid disease, B12 deficiency, infections such as syphilis or HIV, dehydration, or cancer. These conditions are treated very differently, and some are curable.

Lumbar puncture (spinal tap): This test is used to collect and study cerebrospinal fluid (CSF), the fluid that surrounds the brain and spinal cord. Our bodies make about 500ml (approximately 16 ounces) of CSF each day, but there is space for only about 175 ml (6 ounces). Routine examination of CSF can identify conditions such as rare infections, inflammatory processes, and cancer that can mimic FTD. A lumbar puncture also can help assess the presence of normal pressure hydrocephalus. As the CSF flows around as it bathes the brain, it can pick up some of the misfolded proteins accumulating in the brain that are contributing to neurodegenerative conditions like FTD, and some of these can be measured. The lumbar puncture procedure involves inserting a thin needle into the lower area of the back beneath the spinal cord. It takes only a few minutes to collect the fluid. Patients rest for 1 hour following the procedure.

MRI (Magnetic Resonance Imaging): A non-invasive procedure that uses magnets and radio waves to create images of the brain and other organs. MRI is preferred to CT scan for most brain disorders, as it creates images from multiple angles and provides a detailed view of many brain structures not visible by CT scan. Atrophy or shrinkage of specific regions of the brain that might be suggestive of FTD can be identified by MRI. The procedure involves lying flat and still on a table for several minutes. The scanner makes loud thumping noises, but there is no pain or danger from the magnets. Sometimes contrast dyes are injected into the arm vein to enhance the images.

PET (Positron Emission Tomography): PET scanning takes a picture of brain functioning. A glucose PET scan takes a picture of the amount of glucose absorbed by neurons in specific brain regions. This is helpful because glucose is the main source of energy for neurons, and reduced glucose absorption in a specific brain area reflects reduced functioning of the neurons in that brain area. An amyloid PET scan takes a picture of the amount of amyloid in the brain. Amyloid is a misfolded protein that accumulates with age and may play a prominent role in Alzheimer’s disease. A positive amyloid PET scan thus is more consistent with Alzheimer’s disease than FTD.