Aphasia Types: The Complete Classification Guide for SLPs

Aphasia is an acquired language disorder caused by damage to the language-dominant hemisphere — for roughly 95% of right-handed adults, the left hemisphere. It is not a disorder of intelligence, motor speech, or hearing. It is a breakdown in the ability to encode and decode language across modalities: speaking, understanding, reading, and writing. Every classic aphasia type is some combination of those four systems failing in a predictable pattern.

The three questions that classify any aphasia

The Boston classification system, which most coursework and exam items use, is built on three yes/no questions. Answer them in order and the type falls out.

1. Is speech fluent? Fluent means normal phrase length (5+ words), normal prosody, and effortless output — even if the content is empty or full of jargon. Nonfluent means short, halting, effortful, agrammatic output.
2. Is auditory comprehension intact? Can the person follow conversation and multi-step commands?
3. Is repetition intact? Can they repeat phrases like "no ifs, ands, or buts"?

The eight classic aphasia types

Broca's aphasia (nonfluent, comprehension good, repetition poor)

Lesion: left posterior inferior frontal gyrus (Brodmann 44/45). Output is effortful and telegraphic — content words survive, function words and grammatical markers drop out ("wife… store… car… broke"). Comprehension of conversational speech is relatively preserved, but syntactically complex sentences (reversible passives: "the boy was chased by the girl") break down. Awareness of the deficit is high, so depression and frustration are common. Frequently co-occurs with right hemiparesis and apraxia of speech.

Wernicke's aphasia (fluent, comprehension poor, repetition poor)

Lesion: left posterior superior temporal gyrus. Speech flows at normal or even press-of-speech rate with normal melody, but it is filled with paraphasias and neologisms and carries little information ("empty speech"). Auditory comprehension is severely impaired. Anosognosia — reduced awareness of the deficit — is characteristic and is a common exam discriminator versus Broca's. Motor findings are often absent, so these patients are sometimes misdiagnosed as confused or psychiatric.

Conduction aphasia (fluent, comprehension good, repetition disproportionately poor)

Classically attributed to arcuate fasciculus damage connecting temporal and frontal language zones. The signature is a repetition deficit far worse than expected from spontaneous speech, with frequent phonemic paraphasias and conspicuous self-correction — conduite d'approche ("telephone… teledone… telephone").

Global aphasia (nonfluent, comprehension poor, repetition poor)

Large left MCA territory lesion. All modalities severely impaired; output may be limited to stereotypic utterances or recurrent perseveration. Automatic speech — counting, singing, overlearned social phrases, profanity — can persist and is often the first functional entry point for treatment.

Anomic aphasia (fluent, comprehension good, repetition good)

Word-finding failure is the only prominent deficit. Speech is fluent but full of circumlocution and empty words ("the thing you use for the hair… for the head"). Anomic aphasia is the most common end point of recovery from other types and the mildest of the classic profiles.

The transcortical aphasias (repetition intact)

The distinguishing feature of all three transcortical types is spared repetition — the perisylvian language zone is intact and the lesion sits in the surrounding watershed territory.

• Transcortical motor: nonfluent, good comprehension, intact repetition. Looks like Broca's but the patient can repeat long sentences flawlessly. Often echolalic. Lesion anterior/superior to Broca's area.
• Transcortical sensory: fluent, poor comprehension, intact repetition. Looks like Wernicke's but repetition is spared, often with echolalia.
• Mixed transcortical (isolation of the speech area): nonfluent, poor comprehension, intact repetition. Essentially global aphasia with preserved repetition.

Paraphasias: know the difference

• Phonemic (literal): sound substitution — "tephelone" for telephone.
• Semantic (verbal): related word substitution — "fork" for spoon.
• Unrelated verbal: real word, no relationship — "cloud" for spoon.
• Neologism: a nonword — "flimber" for spoon. Neologistic jargon is a Wernicke's hallmark.

Primary progressive aphasia

PPA is neurodegenerative, not vascular, and language is the earliest and most prominent deficit. Three variants: nonfluent/agrammatic (effortful, agrammatic, often with apraxia of speech), semantic (fluent, anomic, impaired single word comprehension, surface dyslexia), and logopenic (word-retrieval pauses and impaired sentence repetition, frequently associated with Alzheimer's pathology). Management emphasizes compensatory strategies, communication partner training, and life participation, because the underlying disease progresses.

Assessment and treatment essentials

Standardized batteries include the Western Aphasia Battery-Revised (yields an Aphasia Quotient) and the Boston Diagnostic Aphasia Examination. Functional measures like the ASHA FACS or CADL-3 capture real-world communication. Evidence-based treatments to know: Melodic Intonation Therapy for nonfluent aphasia, Semantic Feature Analysis and Phonological Components Analysis for anomia, Response Elaboration Training and Verb Network Strengthening Treatment for sentence production, Constraint-Induced Language Therapy for intensive verbal output, and Supported Conversation for Adults with Aphasia for partner training.

How aphasia shows up on the exam

Items rarely ask "define Broca's aphasia." They give a short vignette — fluency, comprehension, repetition, awareness — and ask you to name the type, localize the lesion, or pick the appropriate treatment. Build the habit of scoring the three questions in your head before you read the answer choices. Practice this pattern with targeted aphasia questions.