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Frontotemporal Dementia

Information for clinicians

Introduction
Frontotemporal dementia (FTD) is the most common clinical manifestation of frontotemporal lobar degeneration, a non-Alzheimer circumscribed degeneration of the frontal and temporal lobes.

Demographics and epidemiology
FTD is the second most common degenerative dementia syndrome affecting those under the age of 65 years, accounting for approximately 20% of presenile dementia cases. Age at onset is typically 45-65 years but has been observed to occur in individuals as young as 21 and as old as 85. The disease occurs with equal frequency in males and females. The mean duration of illness is 8 years, ranging from 2-20 years.  

Behavioural changes
Alterations in personality and social conduct are the most salient clinical features of FTD and are pivotal to current diagnostic criteria. Changes in social conduct include socially inappropriate disinhibited behaviour, irritability and egocentricity. Patients become emotionally blunted with a loss of feeling for others. There is early loss of insight. Patients often become apathetic, showing loss of interest in previous hobbies and requiring prompting in self-care and activities of daily living. Some patients become restless and overactive. They may adopt rigid, stereotyped daily routines, becoming irritable if their routine is disturbed.

Changes in eating behaviour are also common. Patients may become gluttonous or develop food fads. A newly acquired preference for sweet foods is often observed.

Cognitive changes
FTD is associated with ‘frontal’ executive dysfunction. Patients show impaired planning, judgement, organisation, attention and mental flexibility. By contrast, primary instrumental abilities of language and visuo-spatial function are well preserved. Although relatives may report forgetfulness, this typically reflects poor attention and concentration rather than primary amnesia. In language, patients typically become economical in speech output and may display echolalia and repetitive verbal stereotypies, eventually becoming mute in late stages of the illness.

Physical changes
There is generally an absence of neurological signs in the early stages of the condition. However, primitive ‘grasp’ reflexes can sometimes be observed and are common in later stages. With progression of the disease, Parkinsonian signs of rigidity and akinesia may emerge. A small proportion of FTD patients develop motor neuron disease.

Genetics
Although the majority of FTD cases are sporadic, a positive family history is present in a proportion of patients. To date, mutations in tau and progranulin have been associated with familial FTD although further work on the penetrance of these mutations is necessary before genetic testing becomes clinically relevant.

Treatment and management
Clinical management of FTD poses some unique challenges. Unlike most patients with dementia, FTD patients are relatively youthful and physically fit. Nevertheless, services are most appropriately provided by psychiatric services for elderly people.

Currently, there exists no curative treatment for FTD. However, pharmacological treatments may alleviate some of the behavioural disturbances associated with the condition. Administration of selective serotonin reuptake inhibitors may reduce stereotypical, repetitive behaviours in some patients. In very behaviourally disturbed patients the use of anti-psychotic agents may be helpful.

Due to the profound behavioural disturbances associated with FTD the burden on carers and families is immense. Management is, therefore, generally focussed on supporting care-givers through psychiatric and voluntary services and provision of day and respite care, with most patients ultimately entering residential care.

Further reading

Neary D, Snowden J, Mann D. Frontotemporal dementia. Lancet Neurology, 2005; 4: 771-780

Neary D, Snowden JS, et al.  Frontotemporal lobar degeneration: a consensus on clinical diagnostic criteria.  Neurology, 1998; 51: 1546-1544. 

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