Fronto Temporal Lobar Degeneration
This section describes a group of dementias, known as Fronto Temporal Lobar Degeneration including Fronto Temporal Dementia, Progressive non-Fluent Aphasia, Semantic Dementia and Pick’s disease. It discusses their causes, diagnoses and symptoms.
What is Fronto Temporal Lobar Degeneration?
This is the name given to dementia when there is degeneration in one or both of the frontal or temporal lobes of the brain. Frontotemporal disorders are the result of damage to neurons (nerve cells) in parts of the brain called the frontal and temporal lobes. As neurons die in the frontal and temporal regions, these lobes shrink. Gradually, this damage causes difficulties in thinking and behaviors controlled by these parts of the brain.
People can live with frontotemporal disorders for 2 to 10 years, sometimes longer, but it is difficult to predict the time course for an individual patient. The disorders are progressive, meaning symptoms get worse over time. In the early stages, people have one type of symptom. As the disease progresses, other types of symptoms appear as more parts of the brain are affected.
The right and left frontal lobes govern mood, behaviour, judgement and self-control. Damage leads to alterations in personality and behaviour, changes in the way a person feels and expresses emotion and loss of judgement.
The right and left temporal lobes are involved in the organisation of sensory input such as what you hear or see. Damage may lead to difficulty placing words or pictures into categories. There is considerable difference in FTLD symptoms depending on which parts of the frontal and temporal lobes are affected. The three main subtypes or variants are:
- Fronto Temporal Dementia (FTD) is the most common subtype or Frontal Variant. It is mainly a disorder of behaviour. People with FTD may be disinhibited or apathetic
- Progressive non-Fluent Aphasia (PA), which was formerly known as Primary Progressive Aphasia (PPA). People with PA may lose the ability to speak or may begin to speak gibberish
- Semantic Dementia (SD) (Progressive Fluent Aphasia) is also known as the Temporal Variant. People with SD may lose the meaning of words and also may become preoccupied with a single activity. Although people with FTLD may be assessed as one of the three subtypes above, the disease will progress and people with FTLD are likely to develop signs and symptoms that are a mixture of two or three subtypes.
FTLD causes progressive and irreversible decline in a person’s abilities over a number of years.
What is Pick’s Disease?
Pick’s disease is a type of Fronto Temporal Lobar Degeneration, named after the German neurologist who first described it in 1892. Pick’s disease affects the frontal lobes, but in some cases can affect the temporal lobe of the brain. If the temporal lobe is damaged, memory is more likely to be affected.
What are the symptoms?
Early symptoms can affect behaviour, and sometimes language. People may show a change in their character and in their social behaviour. For example, they may show insensitivity when they have previously been very considerate of others. A person with FTLD may become obsessive and repeat the same action over and over again. Language problems often occur early in the disease and may range from limited speech to total loss of speech. Repeating phrases over and over, or echoing what others have said are also common symptoms. Instead of being able to find the right word to describe an object, a person with FTLD may give a description of it instead. For instance, instead of naming a watch, the person may refer to something you tell the time with.
Types of Frontotemporal Disorders
Frontotemporal disorders can be grouped into three types, defined by the earliest symptoms physicians identify when they examine patients.
- Progressive behavior/personality decline—characterized by changes in personality, behavior, emotions, and judgment (e.g., behavioral variant frontotemporal dementia).
- Progressive language decline—marked by early changes in language ability, including speaking, understanding, reading, and writing (e.g., primary progressive aphasia).
- Progressive motor decline—characterized by various difficulties with physical movement, including shaking, difficulty walking, frequent falls, and poor coordination.
It can be hard to know which of these disorders a person has because symptoms and the order in which they appear can vary widely from one person to the next. Also, the same symptoms can appear in different disorders. For example, language problems are most typical of primary progressive aphasia but can also appear in the course of behavioral variant frontotemporal dementia.
Who gets Frontal Lobe Dementia?
Frontal lobe dementia, including Pick’s disease, can affect both men and women. Although it can affect people at any age, it usually begins between 40 to 65 years of age.
How is Fronto Temporal Degeneration diagnosed?
There are several techniques such as brain scans, an electroencephalogram (EEG) and neuropsychological tests which can be used to make a probable diagnosis. These tests can help to determine whether the dementia is likely to be FTLD, or another disorder, such as Alzheimer’s disease. Like Alzheimer’s disease however, the diagnosis can only be confirmed after death by examination of the brain tissue.
What causes Fronto Temporal Lobar Degeneration?
About 50% of people with FTLD have a family history of the disease. Those who inherit it seem to have a mutation in the tau protein gene on chromosome 17, leading to abnormal tau protein being produced. Other risk factors are less well known.
How does the disease progress?
The course of FTLD is one of inevitable progressive deterioration. From the onset of the disease, life expectancy is two to fifteen years, with an average of six to twelve years. Death usually comes from another illness such as infection.
Is there treatment available?
Unfortunately, there is not yet a cure for FTLD, nor is there currently any treatment. However secondary symptoms, such as depression, can be helped by medication. Management lies in developing coping strategies. Knowing more about the disease and why the person is behaving as they are can in itself be an effective means of helping people to cope with the disease. Family members and carers can develop their own coping strategies, such as avoiding confrontation and working around obsessions, rather than trying to change the behaviour of those affected.