Physical aspects of Fronto-temporal lobar degeneration

Dr Anna Richardson, Consultant Neurologist

Talking about physical problems in frontotemporal dementia and semantic dementia may at first seem a rather surprising topic as it tends to be more people’s mental health rather than their physical health which is affected in these conditions. However, physical problems do become apparent in the later stages, as well as in rarer forms of the disease.

Brain functions and scientific terms

The term ‘frontotemporal lobar degeneration’ is an umbrella term for the unifying disease process which causes a number of disorders, such as frontotemporal dementia (FTD) and semantic dementia (SD). We know that different areas of the brain are responsible for different psychological functions. For example, the occipital lobe (at the back of your brain) processes visual information, the parietal lobes are responsible for spatial navigation, the temporal lobes (behind your ears) support language and memory functions, whereas the frontal lobes (at the front of your brain) are responsible for planning, strategic thinking and social judgement (see diagram).

Frontotemporal lobar degeneration is a brain disease which generally affects the front parts of the brain (the frontal and temporal lobes). In most people, FTLD affects either the frontal or the temporal lobes of the brain. If it affects mostly the frontal lobes, this gives rise to the syndrome of frontotemporal dementia (FTD), associated with personality and behavioural change. If the temporal lobes are mostly affected, people develop the syndrome of Semantic dementia, associated with a loss of understanding of the meaning of words and objects. In some cases, FTLD may affect both frontal and temporal lobes, and people will exhibit a mixture of both FTD and SD syndromes. In the following sections, we will use the term Frontotemporal lobar degeneration (FTLD) to talk about the disease in general. 

This is just a very brief recap of notions that are covered in more detail in other talks. If you want to refresh your memory or are interested in finding out more general information about FTD and SD, then please have a look at the following talks:

Physical problems secondary to behavioural disorder

People with FTD generally undergo a marked change in personality and behaviour for which they show little insight. In terms of behaviour, they generally fall into one of 2 types: disinhibited or apathetic. People with a ‘disinhibited’ type of behaviour are generally overactive and restless, tending to pace around a lot. People with an ‘apathetic’ behavioural change show a decrease in physical activity, will tend to sit or lie down for large parts of the day and are often quite difficult to persuade to go out. In both subtypes, people remain physically healthy. However, these behavioural changes may be misinterpreted as a physical problem. For example, a person’s loss of mobility due to their apathy and lack of motivation may be interpreted as a physical problem, even though, in reality, the person is fully able to walk. Some people may develop repetitive behaviours, such as repetitively rubbing their hands or legs. Again, this is not because their hands / legs are hurting them physically but is all part of their behavioural change.

Incontinence 
Incontinence can affect certain people with FTLD although it by no means affects everybody. Incontinence is not due to a physical or neurological problem but can arise as part of the behavioural change. For example, people who become very apathetic can exhibit a certain lack of self-care, and neglect their personal appearance. Incontinence may arise because they are no longer embarrassed of their personal appearance in public. Although incontinence in this case is not a physical problem, it can be helped by taking the same medication that is used to treat people with physical bladder problems.

Later stages of the disease - Parkinsonism

People in the late stages of FTLD generally experience some physical problems, such as stiffness and slowness. These are called ‘parkinsonism’ by clinicians, because they resemble in some way the symptoms seen in Parkinson’s disease. People with parkinsonism develop problems in the control of movement. Their movements become slower, their limbs stiffen (this can also affect the neck and trunk) and they sometimes develop a tremor (shaking) of the limbs (although this is less common in FTD).

Relatives generally notice that the person is walking more slowly, with a stooped posture or that their face is less expressive than before. These symptoms emerge in the later stages of the disease because the disease process is spreading deeper into the frontal lobes to parts of the brain that are responsible for the control of movement. Unfortunately, giving people the same medication used for Parkinson’s disease does not improve symptoms as both diseases have different mechanisms. 

The following problems are not seen in FTLD:

  • Epilepsy
  • Muscle jerks
  • Sudden changes in physical state: physical symptoms appear and develop gradually

FTDP-17

Most cases of FTLD are sporadic. Only a small number of cases are inherited and passed on through families. In these families (who carry the FTDP-17 gene), it is often common to see movement disorders associated with FTD, either in the same individual or in different members of the same family. Although small in number, these families have been extensively investigated by scientists who believe that unravelling the genetic basis of the disorder in these families may help us to understand the underlying basis of all forms of the disease, including sporadic ones. 

FTD-MND

Motor-neurone disease (MND) is a rare but well-known disease of the nervous system. Some rare FTLD patients may develop features of MND and present with prominent physical problems in addition to FTD or SD. Changes in physical capacity may be noticed by carers and can be confirmed through neurological examination and neurophysiological tests, where needles are inserted into the muscles to check how well the nerves in the muscles are working. In some cases, people develop MND first and then later acquire symptoms of FTD or SD.