Causes and Symptoms
Frontotemporal dementias
(FTDs) are a group of disorders characterized by degeneration of the frontal and temporal lobes of the brain. These areas in the brain are responsible for language, behavior, and personality. Magnetic resonance imaging (MRI) of the brain can show shrinkage of the brain in these areas (frontal and/or temporal lobes). FTDs can show variable symptoms depending on which parts of the brain may be affected. Most individuals have either behavior changes or language disturbances as their main feature.
Behavior changes associated with FTDs include dramatic personality changes, toward either impulsive and disinhibited or apathetic and listless. Frequently, verbal and facial social cues are unrecognizable to affected individuals. Additional behaviors can include isolation, lack of empathy and sympathy, distractibility, loss of insight, dietary changes (sweet food preferences), neglect of personal hygiene, repetitive behaviors, and decreased motivation. Language changes in FTDs are of two main types: loss of ability to speak as a result of difficulty with word recall (primary progressive aphasia) or loss of ability to understand language (semantic dementia).
Frequently, family members bring affected individuals to medical attention because of these behavioral changes, which go unrecognized to the individual. The onset of FTD can be from age forty to seventy; therefore, individuals can be living with the disease many years before family members notice personality and behavior changes or behaviors begin to interfere with activities of daily living.
There are a few rare types of FTDs that involve movement disorders in addition to dementia. One type is FTD with motor neuron disease (MND). Classical MND is also called amyotrophic lateral sclerosis
(ALS) or Lou Gehrig’s disease. FTD can also be seen with symptoms of Parkinson’s disease. Movement disorder-related symptoms can include tremor, weakness, difficulty swallowing, and poor coordination.
People can be misdiagnosed with psychiatric problems, especially with the young age of onset seen in FTDs. Others can be misdiagnosed with Alzheimer’s disease because of the fact that it is much more commonly seen by physicians.
Men and women are affected equally by FTD. Family history is the greatest risk factor for FTDs, with approximately 50 percent of all FTD cases showing familial inheritance. Mutations in several genes have been shown to cause several types of FTDs. Genetic testing may be offered. Individuals with FTD symptoms will undergo a variety of tests to try to rule out other illnesses that may mimic the symptoms of FTD. These tests may include blood count, electrolytes, liver function, thyroid function, and kidney function. Also, images of the brain via magnetic resonance imaging (MRI) and computed tomography (CT) scanning may be obtained to rule out bleeding or tumors that can cause similar symptoms. Finally, neuropsychological testing may be used to help determine if there are language, memory, and/or reasoning deficits to aid in the diagnosis of FTD.
Treatment and Therapy
FTD is a degenerative disorder. There are no treatments to cure or slow the progression of the brain degeneration. The median duration of illness is six to eight years from onset to death, although the length of time can range from less than two years to more than ten years. Individuals with FTD-MND have a shorter survival time, with a median survival of only three years. Most therapy for individuals with FTDs focuses on managing the symptoms and behaviors seen in the disorder. Speech therapy can be helpful to learn new strategies to aid in verbal and written communication. Caregivers can help reduce behavior problems by avoiding behavior triggers (events or activities), anticipating needs, and maintaining a calm environment. Caregivers should focus on building a support network that includes social services, psychiatric care, support groups, respite care in adult care centers, and/or home health aids. Ultimately, individuals with FTDs will progress to require twenty-four-hour care, and nursing home care may be required. Many patients, if able, may wish to help family members with this planning ahead of time, making the transition for caregivers and family members easier knowing that the affected individual was part of the decision-making process.
Medications currently used to treat the behavioral symptoms of FTD include antidepressants and antipsychotics. These drugs have not shown great success. Therapeutic research related to the genetic causes of FTDs, however, has shown promise. For example, the microtubule-associated protein tau (MAPT) gene can be altered to cause toxic clumps and tangles of MAPT protein. These MAPT tangles are seen in several forms of FTDs. Therapies and drugs designed to prevent or fix the MAPT tangles are currently being designed and tested in animal models. Additional testing and validation will be needed before clinical trials begin in humans.
Perspective and Prospects
FTD was originally described by Arnold Pick in the 1890s. He published a case series of patients in which he described the behavioral and language variants now part of the clinical criteria of FTD. In 1926, two neuropathologists, K. Onari and Hugo Spatz, described the brain findings commonly seen in FTD, including shrinkage of the frontal and temporal lobes and Pick bodies. In the 1980s, the term “frontolobe dementia” and “frontotemporal dementia” were derived in a group of papers trying to define the clinical criteria of FTD and help differentiate the disorder from Alzheimer’s disease. The recent discovery of several mutated genes that can cause FTD symptoms has helped physicians and scientists define the disorder and will only lead to improved diagnosis and treatments for the future.
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