The symptoms of FTD dementia vary depending on which areas of the frontal and temporal lobes are damaged. A person may have one of three main types of FTD:
- behavioural variant FTD
- progressive non-fluent aphasia
- semantic dementia.
As with most forms of dementia, the symptoms can be very subtle at first, but they slowly get worse as the disease progresses.
Behavioural variant FTD
This is the most common type of FTD. Two thirds of people with FTD are diagnosed with this type. During the early stages, changes are seen in the person’s personality and behaviour.
A person with behavioural variant FTD may:
- lose their inhibitions – behave in socially inappropriate ways and act in an impulsive or rash manner. This could include making tactless or inappropriate comments about someone’s appearance
- lose interest in people and things (apathy) – lose motivation, but (unlike someone with depression) they are not sad
- lose sympathy or empathy – become less responsive to the needs of others and show less social interest or personal warmth. They may also show reduced humour or laugh at other people’s misfortunes. This can make the person appear selfish and unfeeling
- show repetitive, compulsive or ritualised behaviours – this can include repeated use of phrases or gestures, hoarding and obsessions with timekeeping. It may also include new interests, such as music or spirituality
- crave sweet, fatty foods or carbohydrates and forget table etiquette. They may also no longer know when to stop eating, drinking alcohol or smoking.
It is common for a person with behavioural variant FTD to struggle with planning, organising and making decisions. These difficulties may first appear at work or with managing finances.
In contrast to those with Alzheimer’s disease, people in the early stages of behavioural variant FTD tend not to have problems with day-to-day memory or with visuospatial skills (judging relationships and distances between objects). Someone with FTD may go walking without obvious purpose but, unlike a person with Alzheimer’s, will often find their way home without getting lost.
Recent research shows that FTD can also affect the sensitivity of people with dementia to physical or environmental stimulation such as temperature, sounds and even pain.
It is unusual for a person with behavioural variant FTD to be aware of the extent of their problems. Even early on, people generally lack control over their behaviour or insight into what is happening to them. Their symptoms are more often noticed by the people close to them.
Language variants of FTD
In the other two types of FTD, the early symptoms are difficulties with language that progressively get worse. These difficulties become apparent slowly, often over two or more years.
In progressive non-fluent aphasia, these problems are with speech – ‘aphasia’ means loss of language. Common early symptoms may include:
- slow, hesitant speech which may seem difficult to produce – a person may stutter before they can get the right word out, or may mispronounce it when they do
- errors in grammar – a person may have ‘telegraphic speech’, leaving out small link words such as ‘to’, ‘from’ or ‘the’
- impaired understanding of complex sentences, but not single words.
In semantic dementia, speech is fluent but people begin to lose their vocabulary and understanding of what objects are. Common early symptoms may include:
- asking the meaning of familiar words (eg, ‘What is “bread”?’)
- trouble finding the right word, leading to descriptions instead (eg ‘the thing for opening tins’), or use of less precise words (eg ‘animal’ instead of ‘cat’)
- difficulty recognising familiar people or common objects.
In the early stages of both language forms of FTD, other mental abilities (such as memory, visuospatial skills, planning and organising) tend to be unaffected.
The rate at which FTD progresses varies greatly, with life expectancy ranging from less than two years to 10 years or more. Research shows that on average, people live for about six to eight years after the start of symptoms but this varies widely
As FTD progresses, the differences between the three types become much less obvious. People with the behavioural variant tend to develop language problems as their condition progresses. They may eventually lose all speech, like a person with one of the language variants.
Similarly, over several years a person with a language variant of FTD (especially semantic dementia) will tend to develop the behavioural problems typical of behavioural variant FTD.
In the later stages of all types of FTD, more of the brain becomes damaged. As a result, the symptoms are often similar to those of the later stages of Alzheimer’s disease. The person may become less interested in people and things and have limited communication. They may become restless or agitated, or behave aggressively. At this late stage, they may no longer recognise friends and family, and are likely to need full-time care to meet their needs.
Overlapping motor disorders
About 10–20 per cent of people with FTD also develop a motor disorder, either before or after the start of dementia. A motor disorder is one that causes difficulties with movement. These motor disorders, which are generally uncommon but more likely in people with this form of dementia, are:
- motor neurone disease
- progressive supranuclear palsy
- corticobasal degeneration.
The symptoms of these three conditions are similar and can include twitching, stiffness, slow movements and loss of balance or co-ordination. In the later stages, they can often cause difficulties with swallowing. Progressive supranuclear palsy and corticobasal degeneration share some symptoms with Parkinson’s disease and are sometimes called ‘atypical parkinsonism’. For more information see rarer causes of dementia.
These motor disorders are all degenerative diseases of the nervous system, meaning that they will get worse over time. If a person has both FTD and motor neurone disease, they can deteriorate more quickly than someone with FTD alone. On average, a person with both conditions will live for two or three years after diagnosis.