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Progressive Aphasia

Information for clinicians

Introduction
Progressive aphasia (PA) is a clinical manifestation of frontotemporal lobar degeneration, a non-Alzheimer circumscribed degeneration of the frontal and temporal lobes. In PA, cerebral atrophy primarily affects the left temporal lobe, but may also extend into the frontal and/or parietal lobes. The disorder is characterised by a progressive deterioration of symbolic communication.

Demographics and epidemiology
PA is a rare disorder and accounts for approximately 15% of cases of frontotemporal lobar degeneration. Age at onset is typically 50-65 years, although symptoms may also appear in later life. The disease occurs with equal frequency in males and females. The mean duration of illness is 8 years, ranging from 4 to 12 years.

Cognitive changes
The predominant characteristic of PA is a progressive disorder of communication. This typically affects the verbal domain although some patients may also exhibit problems in gestural communication. Speech is hesitant and stuttering, reflecting difficulties in word finding. Naming is profoundly impaired and there are frequent phonological paraphasias (e.g. ‘skeet’ for sheep) and transpositional errors (e.g. ‘aminal’ for animal). By contrast, comprehension of words is relatively preserved, at least in the early stages of the disease. Writing, reading and calculation may also become impaired. In the early phases, communication by gesture may remain relatively intact, offering patients an alternative to verbal expression. However, with progression of the disease, use of symbolic gestures deteriorates, so that communication by verbal, written or gestural means becomes increasingly problematic.

Behavioural changes
In the early stages, there are typically no severe alterations in personality. Patients may express frustration at the loss of their communication abilities, indicating preserved insight into their condition. However, as the disease progresses, certain behavioural changes reminiscent of those seen in FTD may emerge. Patients may become apathetic and show reduced insight into their condition. They lose concern and empathy for others and become increasingly self-centred and inflexible. These behavioural changes reflect the extension of pathology into the frontal lobes.

Physical changes
There is often an absence of neurological signs in the early stages of the condition. However, asymmetric rigidity and tremor may occur on the right side of the body, becoming more marked as the disease progresses.

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

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

Despite their profound problems in language and communication, patients typically remain functionally independent in the home, and can carry out activities of daily living.

Currently, there exists no curative treatment for PA. There is some evidence that speech therapy may help communication in the early stages. However, in the later stages, patients become increasingly reliant on their carers and family. Management is generally focused on supporting care-givers through psychiatric and voluntary services and provision of day and respite care.

Further reading

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

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