Looking at Aphasia and Semantic Dementia

by Will Dance

Aphasia (sometimes known as dysphasia) is a condition that affects the brain and leads to the inability or impaired ability to both understand and produce speech due to progressive or sudden brain trauma or damage. Aphasia can be defined as a ‘communication disability’ and it is caused by the damage of the communication centres within the brain. The most common cause of aphasia is stroke (disturbance in the blood supply to the brain) but it is also caused by brain haemorrhages (an artery in the brain bursting and causing bleeding in the surrounding tissue, the bleeding kills brain cells) and brain tumours (a growth of cells in the brain that multiply uncontrollably). There is also a condition called Primary Progressive Aphasia although the cause of this is undecided. Sufferers of aphasia make errors in their speech and at times use the wrong sounds in a word, choose the wrong word or use words together incorrectly. Aphasia affects writing as well as speech. Many individuals with aphasia find it challenging to understand words and sentences they hear or read.

Aphasia affects different people differently. Some people cannot speak at all whereas some can speak; this ranging from use of only a few words to more complex sequences of words. Aphasia can also have an effect on a person’s capability to be able to read, write and also understand or use numbers. Aphasia is incredibly common in the UK, every 11 minutes three people have a stroke (http://www.ukconnect.org/about-aphasia.aspx). On average, a third of those people will have aphasia. In addition there are people who have aphasia due to other conditions (brain tumours or haemorrhages).

There are several types of aphasia, the diagnosis depends upon which area of the communications centre in the brain is most damaged.

‘Broca’s Aphasia’ (also referred to as non-fluent or expressive aphasia) is when a person speaks with short sentences due to not being able to find the words they need to form a complete sentence. These sentences often make sense but they require great effort to produce.

Another type of aphasia is ‘Wernicke’s aphasia’ (also referred to as fluent or receptive aphasia) is when a person speaks in long sentences that may not have meaning or may even make up words. The aphasic person is able to speak normally and use complex sentences, but the words they use do not make sense or they include non-existent words in their speech. A big implication of Wernicke’s aphasia is that many sufferers are often unaware their spoken language makes no sense and may become frustrated when other don’t understand them.

Global aphasia is when the aphasia is very severe, it causes a virtually total reduction of all areas of spoken and written language

Primary Progressive Aphasia is a different kind of aphasia which is characterised by the fact that improvement does not occur over time and rather it is progressive as opposed to being caused by an event such as a stroke. Primary progressive aphasia is degenerative meaning sufferers will continue to lose their ability to speak, read, write, and understand spoken language. It is not caused by stroke or head injury but typically starts as trouble with articulating words which progresses to a total inability to speak.



Semantic Dementia is a form of Primary Progressive Aphasia (PPA) charcterised by the loss of speech related abilities such as finding words when talking and also naming people, places and objects and also finding it hard understanding other people’s speech but whilst still being able to do other things the same. Semantic dementia is a language disorder in which sufferers demonstrate a progressive deterioration of word comprehension, especially nouns and recognizing objects while other cognitive abilities remain oddly intact.

The categorising feature of semantic dementia is difficulty in generating or recognising familiar words. For example, when a patient is presented with a picture of a ‘dog’, they can neither say what it is nor can do they recognise the word when it is told to them, the patient will usually characteristically ask “what is ‘dog’?” when told what the picture is. This happens for rare words first and then common nouns later on. Verbs usually aren’t affected.

The amount of stress the people who care (care givers) for those with semantic dementia are put under is often very great. People who have a relative with this illness often find themselves having to adapt to dealing with a new person because semantic dementia often causes changes in personality. It is very hard to talk with sufferers and to connect with as them as they often will only talk about subjects that interest them and these are often very arbitrary topics. Not being able to connect leads to much emotional stress.


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