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Semantic Dementia

Information for patients and carers

What is Semantic Dementia?
Semantic dementia refers to a progressive loss of the ability to remember the meaning of words, faces and objects, which results from shrinkage of the temporal lobes of the brain. 

What are the symptoms?

1. Language
The initial problem is often with words. Sufferers may have difficulty remembering the names for things and may use words incorrectly (e.g. saying “water” for ‘milk’; “dog” for ‘lion’). Sufferers may also have difficulty understanding what is said.

2. Recognition of faces and objects
It is common for sufferers to have difficulty recognising people whom they do not see regularly.  They may also develop difficulty in recognising things, for example, vegetables in the supermarket.

3. Memory
Sufferers do have a problem with memory, but it is particularly a certain type of memory: memory for what words mean, who faces represent, what objects signify.  This special type of memory is called ‘semantic memory’.  Memory in the sense of remembering to do things at the right time, remembering events and the way to the shops is often well preserved.

4. Personality and behaviour
Sufferers may become inflexible, self centred and less concerned for the feelings of others. They may become preoccupied with a few activities, adopt a fixed daily routine and like to do things at the same time each day. 

Can the sufferer alter his/her behaviour?
No.  Alterations in the sufferer’s behaviour are a direct result of damage to brain cells and are not under their conscious control.  Apparent selfishness or awkwardness is not the result of deliberate wilfulness.

Is the sufferer aware of what is happening to him/her?
The sufferer may have some awareness of difficulties leading to frustration and irritability.  However, usually they do not appreciate the extent of changes from his/her former self in the same way as is evident to the carer.  In many ways the burden of the illness is on the carer rather than the patient.

Are there any physical changes?
Sufferers typically remain physically well.  They may ‘slow up’ a little as the disease progresses.

Will the symptoms become worse?
The disease is progressive, so symptoms do worsen over time.  However, there is wide variation in the speed of progression.  Some people show little decline over the course of a year whereas others change more quickly.  Usually, monitoring a person’s progress over a year will give a good guide as to the likely future rate of progression.

Are there ways to help?
Encouragement of pursuits in which the sufferer is successful can help to boost confidence and maintain independence. 

Understanding is helped by doing.  Vocabulary relating to the sufferer’s daily life will be more meaningful than other vocabulary; objects that the patient uses will be recognised better than those which are not used; pursuits in which he/she is actively engaged will continue to be meaningful for longer than those in which the patient has no participation.  Encouraging and maintaining a variety of life experience will help to slow symptom progression.

The sufferer’s difficulty is in understanding individual word meaning.  It can help understanding if words are put into context: speaking in complete sentences is better than communicating in short phrases or by single words.

At what age are people affected?
The condition most commonly affects people between 50 and 65, but can occur in both younger and older people.  The greater prevalence in middle age is one factor that distinguishes this from other forms of dementia, such as Alzheimer’s disease, which occur most commonly in the elderly.

What is the cause? 
The disorder is a degenerative condition of the brain. This means that cells in certain parts of the brain gradually cease to function properly, which is why symptoms develop. The cause of this degeneration is at present not fully understood and is the key question for current research. However we know that this condition is not caused by external environmental or lifestyle factors, such as diet, occupational exposure or head injury. It can affect people from all walks of life and does not result from ‘over-use’ or ‘under-use’ of the brain.

Is semantic dementia inherited?
Most cases of semantic dementia occur ‘out of the blue’, and no other family members are affected. In a very small number of cases, the condition runs in the family and is passed on through the genes. Families with a genetic predisposition are generally already aware of this, as they know of other relatives who have developed similar symptoms. If you have queries or concerns please let us know. Our colleagues in the Genetics Department are happy to provide individual advice.

Is there any treatment?
There is currently no treatment for the underlying disease. However, there are some drugs available, which are designed to alleviate symptoms of the disease.

Why haven’t I heard of semantic dementia before?
In the past the general belief was that dementia sufferers all had the same disease, usually thought to be Alzheimer’s disease. It has only recently that distinct disorders like semantic dementia have been recognised.  Another difficulty is that people use different names to refer to the same condition, which can make finding information confusing. Semantic dementia is known to be related to frontotemporal dementia, leading some people to refer to semantic dementia as “the temporal variant of frontotemporal dementia”.  

Is there research into the condition?
Yes, certainly. The interest in this area of research increases each year. The aim is to understand the mechanisms that underlie this disorder, so that better treatments can be developed. Our department is an active contributor to research in FTD and other degenerative disorders. If you would like to find out more about the research carried out in our unit, please visit our website or ask when you attend the clinic.