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Frontal lobe dementia or frontotemporal dementia (FTD) represents a unique group of neurodegenerative disorders that account for approximately 10 percent of all cases of dementia and tend to occur in people between the ages of 45 and 64. The symptoms of each disorder can vary, depending on the part of the frontal or temporal lobes affected, but can include behavior and personality changes, language dysfunction, and motor skill impairment.
There are three main types of frontal lobe dementia or frontotemporal dementia, some of which are divided into subtypes:
- behavioral variant frontotemporal dementia (bvFTD)
- primary progressive aphasia (PPA)
- frontotemporal movement disorders
What Causes Frontal Lobe Dementia/Frontotemporal Dementia?
Scientists don’t know what causes the majority of cases of frontal lobe dementia. However, abnormal accumulations of proteins, either tau or TDP-43, have been found during autopsy in the brains of people who suffered from frontal lobe dementia.
Furthermore, a number of genes (including the tau or MAPT gene and the PGRN gene) linked to the abnormal production of these proteins have been identified and are responsible for the disease in the 15 to 40 percent of people who suffer from a hereditary form of it.
Symptoms of Frontal Lobe Dementia
Each type or subtype of frontal lobe dementia has specific symptoms and yet there can also be overlap between the different types, particularly as the disease progresses.
- Behavioral Variant Frontotemporal Dementia (bvFTD): BvFTD is the most common form of frontal lobe dementia and is characterized by changes in behavior, personality, and judgment. In particular, affected people tend to lose empathy and control of their conduct. As the condition progresses, language and motor skills may also be compromised. BvFTD was formerly called Pick’s disease after the German scientist who first identified abnormal collections or “Pick bodies” (we now know to be tau proteins) in the brains of affected individuals. Not everyone with bvFTD has these collections, however.
- Primary Progressive Aphasia (PPA): PPA represents the second most common form of frontal lobe dementia and is divided into three subtypes, all of which are characterized by disruptions in the ability to communicate with language, either written or spoken.
- Semantic PPA: People affected with this variant of PPA can speak fluid, grammatically correct sentences, which may not be relevant to the conversation they are in. They may also lose the ability to understand or recall words.
- Agrammatic PPA: This variant of PPA is characterized by nonfluent speech that may ultimately progress to the inability to speak at all.
- Logopenic PPA: Individuals suffering from this variant have no difficulty understanding language and no difficulty with grammar, but they have trouble finding the right words to use in conversation.
Frontotemporal Movement Disorders
There are four rare movement disorders considered to be part of the frontal lobe dementia/frontotemporal dementia spectrum:
- Corticobasal syndrome (CBS): People suffering from CBS have neurodegenerative changes in their brain that affect their ability to initiate movement despite having normal strength. This impairment is typically most notable in the hands and arms.
- Progressive supranuclear palsy (PSP): Patients with PSP develop problems with walking, posture, and upper body stiffness. A hallmark of the condition is difficulty with eye movements. Behavior issues can also occur as the disease progresses.
- Frontotemporal dementia with Parkinsonism: Patients suffering from this variant can experience both the behavior and language changes seen in frontal lobe dementia as well as the symptoms characteristic of Parkinson’s disease (muscle stiffness, balance impairment, etc). A hereditary form of this condition involves a mutation in the tau gene.
- Frontotemporal dementia with amyotrophic lateral sclerosis (FTD-ALS): This disorder is a combination of bvFTD and ALS (also known as Lou Gehrig’s disease). People suffering from this disease experience progressive muscle weakness, behavioral changes, and language impairment.
How Is Frontal Lobe Dementia Diagnosed?
Diagnosing this group of disorders can be difficult because the behavior and language changes can mimic psychiatric disorders and the movement impairments can mimic other degenerative neurologic conditions. Unless an individual has an inherited form of the disease and can be tested for one of the known mutations, the diagnosis is made by taking a detailed personal and medical history (requiring input from friends and family), performing a thorough physical exam, obtaining laboratory testing to rule out metabolic causes of dementia, and using imaging studies to identify abnormalities in the frontal or temporal lobes.
Magnetic resonance imaging (MRI) can reveal structural abnormalities and positron emission tomography (PET) or single photon emission computed tomography (SPECT) can evaluate activity, including glucose and oxygen usage, in these areas of the brain.
How Is Frontal Lobe Dementia Treated?
There is no specific treatment and no cure for any of the diseases that fall within the frontal lobe dementia spectrum. Treatment involves managing symptoms to the best extent possible. Here are five strategies commonly used:
- Antidepressants or antipsychotic medications: These meds have been used in some patients to manage behavioral symptoms.
- Alzheimer’s disease medications: Doctors have tried using these medications in some patients to manage their cognitive impairment.
- Speech therapy: Speech therapists who have experience with frontal lobe dementia can help identify tools and methods for communication as language impairment worsens.
- Occupational/physical therapy: These therapies can help patients deal with some of the rigidity and stiffness seen in the movement disorders. Therapists can also help identify assistance devices (e.g., walkers) that can help facilitate better balance.
- Parkinson’s disease medications: These drugs may be helpful in the short term for some patients suffering from frontotemporal dementia with Parkinson’s.
Assembling a team of specialists that includes doctors, therapists, nurses, and patient advocates is ultimately the most important factor in managing frontal lobe dementia for both the patient and their caregiver.
The editors at Duke Medicine’s Health News answer a common question about ALS:
Q: A dear friend has just been diagnosed with amyotrophic lateral sclerosis. Are there new treatments in recent years for the disease?
A: Amyotrophic lateral sclerosis (ALS), commonly known as Lou Gehrig’s disease (after the famous baseball player of the 1930s), is a disease of the nervous system that progressively weakens muscles, causing loss of physical function so you can no longer walk, talk, eat or breathe, and eventually resulting in death; most people die within three to five years of diagnosis, though some can live more than 10 years with the disease. Early symptoms include muscle cramps, muscle twitches, tight, stiff muscles, muscle weakness, slurred and nasal speech, and difficulty chewing or swallowing. To date, there is no cure for the disease, though some medications can slow its progression. In ALS, motor neurons in your brain and spinal cord break down and die, preventing your brain from sending messages to your muscles. This causes them to weaken, leading eventually to loss of control over their movements, and inhibiting activities of daily living. ALS is a heritable disease and frequently runs in families. It’s thought that genetic changes are associated with ALS. However, “sporadic” ALS is more common and the cause of 90 to 95 percent of all cases. There currently are two FDA-approved drugs, riluzole (Rilutek) and edaravone (Radicava), that slow progression of the disease, while physical therapy can help strengthen unaffected muscles. ALS usually afflicts people between ages 40 and 70, and the Centers for Disease Control and Prevention estimate that between 14,000 and 15,000 Americans have ALS.
Originally published in June 2016 and updated.
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