Common causes of aphasia include strokes, traumatic brain injuries, complications from brain surgery, and progressive neurological diseases, such as dementia. Aphasia is a common side-effect of damage to the left-hemisphere of the brain, as this hemisphere is responsible for language production. Physical symptoms of aphasia often include weakness in the right-hand side of the body, since this area is controlled by the left-hemisphere. It is estimated that 1/3 of stroke victims are left with some form of aphasia, and over 250,000 people in Britain currently show signs of the condition. A common misconception is that people with impaired communication are of below average intelligence, but this is not the case for most people with aphasia. Evidence suggests many aphasia sufferers are able to think and process thoughts normally, despite having problems articulating said thoughts. There are two types of aphasia, with each affecting patients differently. Broca’s aphasia affects language production, meaning patients can comprehend language as normal, but struggle to produce speech themselves. Wernicke’s aphasia affects language comprehension, meaning sufferers can produce language as normal, but their utterances often make little sense, as they struggle to understand spoken interactions.