Non-verbal cognitive impairment and semantic-lexical disintegration in aphasia

Three non-verbal tests of "Symbolic Gesture Interpretation," "Conceptual Relationships" and "Drawing Objects from Memory" were administered to large groups of aphasics, normal controls and non-aphasic right and left brain-damaged patients, in order to check two alternative interpretations that have been advanced to explain the frequent association between aphasia and non-verbal cognitive disturbances. According to the first interpretation, the concomitance of linguistic and cognitive disorders could be due to the anatomical contiguity between language areas and cortical structures subserving cognitive functions. According to the second interpretation, the lack of a complete relationship between cognitive impairment and severity of aphasia could be due to the fact that only some components of the a phasic symptom-complex (namely, a breakdown of the semantic-lexical structures) are selectively linked to the disruption of non-verbal cognitive activities. Results of our research did not support the anatomical contiguity hypothesis, since we were unable to find patients suffering from a well-localized left-hemisphere lesion, showing a clear-cut cognitive impairment in the absence of aphasic disturbances. They showed, on the contrary, that an important relationship exists in aphasia between non-verbal cognitive disorders and disruption of the semantic-lexical level of integration of language, since in all the tasks administered to our patients the poorest scores were obtained by aphasic patients presenting evidence of a semantic-lexical impairment.