Does aphasia affect intelligence?

No. Aphasia is strictly a language disorder. It affects the ability to communicate through words — speaking, understanding, reading, and writing — but does not impair intelligence, memory, personality, or the ability to think and reason.

Is aphasia the same as dementia?

No. Most aphasia is caused by stroke or brain injury and does not affect general cognition. Primary progressive aphasia (PPA) can be associated with frontotemporal dementia, but stroke-related aphasia — the most common form — does not involve broader cognitive decline.

8 Common Aphasia Myths — and What the Science Actually Says

Aphasia is more common than Parkinson's disease or multiple sclerosis, yet public understanding of the condition lags far behind. Misconceptions circulate in families, online communities, and sometimes even in clinical settings. These myths carry real costs: they lower expectations for recovery, reduce therapy intensity, and leave families ill-equipped to support their loved ones.

Here are the eight most common myths and what the evidence actually shows.

Myth 1: Aphasia affects intelligence

This is the most pervasive and most damaging myth. Aphasia affects language — the system of sounds, words, and grammar the brain uses to communicate. Intelligence, memory, personality, and the ability to think, reason, and understand the world are all intact.

A person with severe Wernicke's aphasia who cannot understand a spoken sentence still has their full cognitive capacity. A person with global aphasia who can produce only a single syllable still has their full inner life. The inability to express a thought in words is not the same as having no thought.

Myth 2: Aphasia only affects speaking

Aphasia is a full-language disorder. Depending on the type and severity, it can affect any or all of: speaking, understanding spoken language, reading, writing, and processing numbers. Some people with aphasia have preserved speech but cannot read; others can read but cannot write; others struggle with all four modalities simultaneously.

Myth 3: You should speak loudly to someone with aphasia

Aphasia does not affect hearing. Speaking more loudly does not help and can feel condescending. What does help is speaking more slowly, using shorter sentences, leaving more time for the person to respond, and supplementing speech with gesture and writing.

Myth 4: Aphasia is rare

The National Aphasia Association estimates that approximately 2 million Americans currently live with aphasia, with roughly 180,000 new cases each year. It is more common than Parkinson's disease, cerebral palsy, or muscular dystrophy. The perception of rarity partly reflects how little public attention aphasia receives compared to conditions with similar prevalence.

Myth 5: Aphasia is caused only by stroke

Stroke accounts for roughly 80% of aphasia cases and is by far the most common cause. But aphasia can also result from traumatic brain injury, brain tumours, infections affecting the brain, and progressive neurological diseases. Non-stroke aphasia often presents with different recovery trajectories and requires different treatment planning.

Myth 6: People with aphasia must also have physical disabilities

Stroke frequently affects both motor and language systems, which is why aphasia and hemiplegia often occur together. But they are separate effects of separate brain damage. Some people experience aphasia without any physical symptoms. Others have severe motor impairment with no language difficulty. The two conditions are correlated, not linked.

Myth 7: Aphasia recovery stops after one year

This myth originates from observations of spontaneous recovery — the biological healing process that largely completes within three to six months post-stroke. But spontaneous recovery and therapy-driven recovery are distinct processes.

The NIDCD states that some people continue to improve for years after stroke. Multiple randomised controlled trials have documented meaningful language gains in patients with chronic aphasia when therapy intensity is adequate. A case study in PubMed documents continued improvement in global aphasia 25 years post-onset.

The factor that predicts late-phase recovery is not time since stroke. It is therapy intensity.

Myth 8: Aphasia means someone cannot communicate at all

Communication is broader than speech. People with severe aphasia often retain significant ability to communicate through gesture, facial expression, drawing, writing individual letters or words, or pointing to pictures. The goal of speech therapy is not exclusively to restore spoken language — it is to maximise communication through whatever channels are most functional for each individual.

If you support someone with aphasia, our guide on how to talk to someone with aphasia covers practical strategies that make everyday communication easier for both parties.