Cognitive deficit and aphasia – a challenging diagnosis

Abstract

O ne of the greatest challenges in cognitive neurology is to determine severity of cognitive impairment in patients with aphasia. Most of the cognitive evaluation is performed through language assessment; lesions causing aphasia can be spread in some different brain areas by committing different networks and, consequently, different cognitive domains. Otherwise, verbal based evaluations could show a false positive impairment.One of the vascular cognitive impairment (VCI) criteria classified it into vascular mild cognitive impairment and vascular dementia, based on functional impairment and number of evaluated cognitive domains. The neuropsychological evaluation must include memory, visuospatial, language, and executive domains 1 . The most recent diagnostic criteria divides VCI into mild cognitive disorder and dementia or major cognitive disorder; there is a recommendation to evaluate praxis-gnosis-body schema, and social cognition, besides previous cognitive domains 2 . In both of them there are no concerns about cognitive evaluation in aphasic patients, which could be unsuitable in most studies.Stud ies in tertiary outpatient clinics report a prevalence of vascular dementia between 24.9 and 32.25%; and among presenile dementia there was a prevalence of 36.9% 3,4,5. There are a few considerations regarding aphasia in these studies. In a prospective study, that have also included aphasics, frequency of VCI was 16.8% in 12-month follow-up 6 . In the majority of the studies, aphasic patients have shown poor performance in attention, executive functions, working memory, and short-term memory 7,8,9 . The study published in this number of Arq Neuropsiquiatr tries to fulfill a gap in this issue in Brazil, characterizing cognitive deficit in a sample of first-stroke patients. Bonini and Radanovic have evaluated 47 stroke patients without depression (non-aphasics: left hemisphere lesion: 17, right hemisphere lesion: 9; and 21 aphasics) with a comprehensive neuropsychological battery; functional activities and quality of life were measured, as well. Aphasics presented a poorer performance on digit span, verbal and visual memory, constructional praxis recall, clock design test, and phonemic verbal fluency. Quality of life was better in right hemisphere lesion and non-aphasic patients 10 . Aphasia severity correlated with scores in the Trail Making Test (TMT) part B, Digit Span forwards and backwards, and Gesture Praxis in this study. In another report, only attention was correlated with aphasia severity 9 .Although this study has limitations as a small number of patients with heterogeneous vascular lesions, it is needed to highlight the importance of the development of specific batteries for evaluating cognition in aphasic patients.Difficulties on interpretation of cognitive deficit in aphasics are relatively common, according to different lesioned topographies, involvement of cortical and subcortical areas, and white matter tracts, near common language areas 11 . More studies must be performed in Brazil to evaluate cogni...