Signs and symptoms of prion disease

Behavioural Symptoms

Often mood disturbance e.g. aggression or loss of interest and personality changes persist into the illness.  Anxiety and depression are fairly common features.  There may also be a lack of social judgement and disinhibition.  People may prefer to keep to familiar routines, changes in the regular daily pattern of events, or new faces may cause distress and anxiety.

Communication Problems

Speech tends to become slurred (dysarthria) and quiet and as a result speech may become hard to understand, making communication difficult.  There is often a reduction in the content of language, word finding difficulties and there may be repetition of words or sentences.  Eventually the person can become mute.  As the illness progresses the ability to read and write are gradually lost.  Problems may occur with understanding written material and with spelling and signing forms; the person may also have difficulty following instructions. 

Memory/Cognitive Deficits 

Problems develop with memory and thinking and there is often a general decline in intellect.  There may be forgetfulness of day to day events, often accompanied by disorientation and poor concentration or attention.  Everyday skills that we take for granted may be lost.  Typically the person affected will forget the day and date.  They may also start to forget how to carry out everyday skills, for example making a cup of tea.  In the latter stages of the disease the person may become increasingly unaware of their immediate environment and the people around them.

Movement Problems

Initially there may be a disturbance in balance and gait, leading to unsteadiness (ataxia).  Walking will therefore be affected and so extra care will have to be taken to try to prevent falls.  Involuntary rhythmic muscle contractions leading to jerky movements (myoclonus) and difficulties co-ordinating hand movements leading to apparent clumsiness.  Shakiness (tremor) and stiffness (rigidity) are often seen.  As movements become increasingly uncoordinated the individual will need help with carrying out their daily activities, for example, personal hygiene and use of the toilet.

Swallowing Problems

With the progression of the disease there may also be difficulty in swallowing.  There are a number of strategies, which may make swallowing easier and an assessment by a speech and language therapist can identify problems and give advice regarding strategies to help.

As swallowing becomes increasingly difficult in the later stages of the disease, it may be suggested that nutrition be supplemented with tube feeding.  This issue will require careful consideration and is rarely done in prion disease.  Relatives need support in making an informed decision.  A speech and language therapist, Macmillan nurse, dietician as well as your own GP may be able to offer advice.

Visual/Perceptual Problems

Visual problems include double vision and difficulty moving eyes to follow objects. Hallucinations are fairly common.  There may be a failure to understand and correctly interpret visual stimuli.  There may be misidentification of objects/people, whereby something/someone may not be recognised accurately. 

Some patients may suffer from what is known as cortical blindness, a condition in which an individual appears to be blind (although the eyes themselves are normal), due to damage in the visual processing and interpretation areas of the brain.

Seizures

Very occasionally a person may suffer from seizures in the later stages of the disease. Medication is available to help control seizures should they occur.