Thought & Speech

Aphasia

Aphasia is a disorder of language resulting from interference with specific areas of the brain responsible for producing or understanding speech. It is included alongside the primarily psychiatric speech disorders of this chapter because comparing the two helps clarify what is distinctive about disorders such as schizophasia, which can superficially resemble aphasia but arise from a different underlying process.

In clinical practice, aphasias have traditionally been grouped into three broad categories according to which aspect of language is chiefly affected: receptive aphasias, in which understanding is chiefly impaired; intermediate aphasias, which involve a more mixed or specific disturbance; and expressive aphasias, in which the production of speech is chiefly impaired.

Also known as

Dysphasia

An alternative name for the same category, sometimes used to indicate a partial rather than complete disturbance of language.

Recognition features

• A disturbance of language — understanding, production, or both — resulting from a specific, identifiable disturbance of brain function
• Distinct sub-types are associated with distinct patterns of brain lesion location
• The severity of the language disturbance is generally disproportionate to any accompanying general intellectual impairment
• May coexist with other neurological signs relevant to the underlying cause

Eliciting it at interview

• Assess spoken language across its different components: comprehension, spontaneous speech, repetition, naming, reading, and writing, since different aphasia sub-types affect these unevenly
• Take a careful neurological history and consider examination and imaging where an organic cause is suspected
• Distinguish carefully from psychiatric speech disorders such as schizophasia, which can resemble aphasia superficially but arise from a different underlying process

Distinguishing features

• Differs from schizophasia in generally having an identifiable neurological cause and a disproportionate impact on language specifically, as against broader thought disorganisation
• The specific pattern of language components affected (comprehension versus production, spontaneous speech versus naming) helps localise the underlying lesion and distinguish between sub-types
• Related conditions such as the agnosias, in which sensation is intact but recognition is impaired, are conceptually adjacent but distinct from aphasia itself

Common misconceptions

• That all disturbances of speech in a psychiatric patient reflect the underlying mental illness; aphasia has a specific neurological basis and should always be considered, particularly when the pattern or history suggests an organic cause
• That aphasia and schizophasia are simply different names for the same disturbance; despite superficial resemblance in some cases, they are generally understood to arise from different underlying processes

Related phenomena

Schizophasia · Receptive Aphasia · Intermediate Aphasia · Expressive Aphasia

Practice this

Following a confirmed left-hemisphere stroke, a patient has marked difficulty understanding spoken instructions and producing meaningful speech, while other aspects of his thinking and behaviour remain relatively coherent and organised. What general category of disturbance is this? · A patient with a confirmed brain tumour affecting the left temporal lobe has marked difficulty finding the right words in conversation, though her comprehension of what is said to her remains largely intact, and there are no other signs of broader psychiatric disturbance. Before revealing the answer: is this best classified as aphasia? · A patient's speech is severely disorganised and hard to follow. Before revealing the answer, decide what distinguishes schizophasia from aphasia. · You suspect a patient's speech disturbance may be aphasia rather than a primarily psychiatric speech disorder such as schizophasia. Which single line of enquiry would most usefully help clarify this? · A patient's language disturbance following a confirmed stroke is disproportionate to any accompanying disorganisation of his broader thinking. Why is this disproportion clinically significant?

Illustration

After a small stroke, a 70-year-old retired teacher who previously spoke fluently and in complex sentences now struggles noticeably with specific aspects of language while her general reasoning and memory for events remain otherwise clearly intact, prompting her family doctor to refer her for a focused neurological assessment rather than treating it as a general cognitive decline.

References

• Casey, P. & Kelly, B. (2019). Fish's Clinical Psychopathology, 4th ed. Ch. 4, 'Disorders of Thought and Speech'.