Aphasia affects everyone differently, but most people will have difficulty expressing themselves or understanding things they hear or read.

If aphasia has been caused by a sudden brain injury, such as a stroke or severe head injury, symptoms usually develop straight after the injury.

In cases where there's gradual damage to the brain as a result of a condition that gets worse over time, such as dementia or a brain tumour, the symptoms may develop gradually.

Someone with expressive aphasia experiences difficulty communicating their thoughts, ideas and messages to others.

This may affect speech, writing, gestures or drawing, and causes problems with everyday tasks like using the telephone, writing an email, or speaking to family and friends.

People with expressive aphasia may have some of the following signs and symptoms:

• slow and halting speech – with difficulty constructing a sentence
• struggling to get certain words out – such as the names of objects, places or people
• only using basic nouns and verbs – for example, "want drink" or "go town today"
• spelling or grammatical errors
• using a wrong but related word – such as saying "chair" instead of "table"
• including nonsense words or their speech not making sense (speech-sound errors)

A person with receptive aphasia experiences difficulty understanding things they hear or read. They may also have difficulty interpreting gestures, drawings, numbers and pictures.

This can affect everyday activities such as reading an email, managing finances, having conversations, listening to the radio, or following TV programmes.

People with receptive aphasia may have some of the following signs and symptoms:

• difficulty understanding what people say
• difficulty understanding written words
• misinterpreting the meaning of words, gestures, pictures or drawings
• giving responses that may not make sense if they've misunderstood questions or comments
• not being aware of their difficulties with understanding, or their own speech errors

People with the most common types of dementia, such as Alzheimer's disease and vascular dementia, usually have a mild form of aphasia.

This often involves problems finding words and can affect names, even of people they know well.

It doesn't mean they don't recognise the person or don't know who they are, they just can't access the name or get mixed up.

Primary progressive aphasia

This is a rare type of dementia, where language is heavily affected. As it's a primary progressive condition, the symptoms get worse over time.

Usually, the first problem people with primary progressive aphasia (PPA) notice is difficulty finding the right word or remembering somebody's name.

The problems gradually get worse, and can include:

• speech becoming hesitant and difficult, and making mistakes with the sounds of words or grammar
• speech becoming slow with short, simple sentences
• forgetting the meaning of complicated words, and later also simple ones, making it more difficult for them to understand other people
• speech becoming more vague and the person having difficulty being specific or clarifying what they're saying
• becoming less likely to join in with or start conversations

A person with PPA may also experience other symptoms later in their illness, including:

• changes in their personality and behaviour
• difficulties with memory and thinking – similar to Alzheimer's disease
• difficulties with movement – similar to Parkinson's disease