Aphasia and Brain damage
It may not be possible to understand and study the behavior of normal function of the brain by studying the patients with damaged capabilities because each patient may have different level of symptoms which may not completely reveal what is actually occurring with the brain cells. Research has also suggested that brain can get affected due to some other diseases which may be entirely not correlated with the neuro-linguistic capabilities of the individual.
Aphasia is a very peculiar type of disease which may render the capability of speaking and writing difficult for a patient. It is though argued that the patients with the Aphasia may be able to speak but their writing capability is greatly impaired. It is also important to understand that the patients with known symptoms of Aphasia may also face other diversified nature of impairments in their language development.
Phonological disorder and Aphasia
Phonological disorder is one of the most common associated problems with the patients of Aphasia as in agrammatism patients often lose control over their ability to speak grammatically correct language. Since Syntactic knowledge requires the brain to memorize certain words to effectively use them under a particular system therefore agrammatism may involve loss of syntactic knowledge and patients may suffer.
Patients with the history of Aphasia however, also lack the ability to memorize the pictures and words in their visual form therefore patients with agrammatism and loss of syntactic knowledge would behave in rather abnormal manner. Due to their inability to memorize and comprehend words and other forms of expression their overall inability for lexical and sublexical processing of spoken words. (Warms).
Warms, Tanya L. “Lexical and sublexical processing in aphasia.” Journal of Neurolinguistics 9.1 (1995): 1-7.