Dimitrios Kasselimis

Short-term and working memory impairments in aphasia.

The aim of the present study is to investigate short-term memory and working memory deficits in aphasics in relation to the severity of their language impairment. Fifty-eight aphasic patients participated in this study. Based on language assessment, an aphasia score was calculated for each patient. Memory was assessed in two modalities, verbal and spatial. Mean scores for all memory tasks were lower than normal. Aphasia score was significantly correlated with performance on all memory tasks. Correlation coefficients for short-term memory and working memory were approximately of the same magnitude. According to our findings, severity of aphasia is related with both verbal and spatial memory deficits. Moreover, while aphasia score correlated with lower scores in both short-term memory and working memory tasks, the lack of substantial difference between corresponding correlation coefficients suggests a possible primary deficit in information retention rather than impairment in working memory.

Age, gender, and education effects on vocabulary measures in Greek

Background: Assessment of lexical/semantic knowledge—the ability to retrieve phonological, lexical, and general (semantic) information from long term memory—can be performed with a variety of tests varying in response requirements. Aims: The present study explores the impact of demographic variables on three such tests. Methods & Procedures: The Peabody Picture Vocabulary Test-Revised (PPVT-R), the Vocabulary subtest from the Wechsler Abbreviated Scale of Intelligence (WASI), and the Boston Naming Test (BNT) were used in a representative sample of 500 Greek community-dwelling adults aged 50–84 years. Outcomes & Results: Education effects were generally stronger than age effects, and were strongest on the WASI. Age effects (independent of educational level) were highest for the BNT and lowest for the WASI Vocabulary. Relationships among tests and also between each vocabulary test and an index of non-verbal intelligence are also discussed.

Are memory deficits dependent on the presence of aphasia in left brain damaged patients

While memory deficits in aphasia have been reported in several studies, it has been suggested that these deficits are not due to the presence of aphasia, but rather to the left hemisphere lesion per se. In order to investigate this hypothesis, we tested 64 aphasic and 15 non-aphasic patients with left brain damage on verbal and visuospatial span tasks. Analyses revealed lower than expected performance on all four primary memory tasks for the aphasic, but not for the non-aphasic group. Moreover, comparison of the three lesion-location groups (posterior, anterior, and global) did not reveal statistically significant differences. The present data show that aphasic patients demonstrate memory deficits, which are not specific to the verbal modality, and contradict the notion that primary memory impairment is not due to the presence of aphasia, but rather to a lesion in the left hemisphere per se. Overall our study suggests that verbal and visuospatial, primary memory deficits in patients with left hemisphere lesions are possibly dependent on the presence of aphasia, but not on lesion location or lesion size.

Age-Related Decline in Verbal Learning Is Moderated by Demographic Factors, Working Memory Capacity, and Presence of Amnestic Mild Cognitive Impairment

Age-related memory changes are highly varied and heterogeneous. The study examined the rate of decline in verbal episodic memory as a function of education level, auditory attention span and verbal working memory capacity, and diagnosis of amnestic mild cognitive impairment (a-MCI). Data were available on a community sample of 653 adults aged 17-86 years and 70 patients with a-MCI recruited from eight broad geographic areas in Greece and Cyprus. Measures of auditory attention span and working memory capacity (digits forward and backward) and verbal episodic memory (Auditory Verbal Learning Test [AVLT]) were used. Moderated mediation regressions on data from the community sample did not reveal significant effects of education level on the rate of age-related decline in AVLT indices. The presence of a-MCI was a significant moderator of the direct effect of Age on both immediate and delayed episodic memory indices. The rate of age-related decline in verbal episodic memory is normally mediated by working memory capacity. Moreover, in persons who display poor episodic memory capacity (a-MCI group), age-related memory decline is expected to advance more rapidly for those who also display relatively poor verbal working memory capacity.

Why is it difficult to predict language impairment and outcome in patients with aphasia after stroke

One of the most devastating consequences of stroke is aphasia. Communication problems after stroke can severely impair the patients quality of life and make even simple everyday tasks challenging. Despite intense research in the field of aphasiology, the type of language impairment has not yet been localized and correlated with brain damage, making it difficult to predict the language outcome for stroke patients with aphasia. Our primary objective is to present the available evidence that highlights the difficulties of predicting language impairment after stroke. The different levels of complexity involved in predicting the lesion site from language impairment and ultimately predicting the long-term outcome in stroke patients with aphasia were explored. Future directions and potential implications for research and clinical practice are highlighted.

Reading Fluency Estimates of Current Intellectual Function: Demographic Factors and Effects of Type of Stimuli

The study explores the potential clinical value of reading fluency measures in complementing demographic variables as indices of current intellectual capacity. IQ estimates (based on the PPVT-R, WASI Vocabulary and Block Design subtests) were obtained from a representative, non-clinical sample of 386 Greek adults aged 48–87 years along with two measures of reading efficiency (one involving relatively high-frequency words—WRE—and the second comprised of phonotactically matched pseudowords—PsWRE). Both reading measures (number of items read correctly in 45 s) accounted for significant portions of variability in demographically adjusted verbal and performance IQ indices. Reading measures provided IQ estimates which were significantly closer to those predicted by demographic variables alone in up to 22% of individuals with fewer than 7 (across all ages) or 13 years of formal education (in the 70–87 year age range). PsWRE scores slightly outperformed WRE scores in predicting a person’s estimated verbal or performance IQ. Results are discussed in the context of previous findings using reading accuracy measures for low-frequency words with exceptional spellings in less transparent orthographic systems such as English.

Effects of demographic variables and health status on brief vocabulary measures in Greek

Background: Assessment of lexical/semantic knowledge is essential on a number of diagnostic situations. Since more than one test is typically required, brief assessments would be useful as part of an extensive neuropsychological battery. Aims: The present study reports the effects of demographic variables and reported health status on performance on the short forms of three such tests adapted into Greek. Methods & Procedures: Tests used were PPVT-R, WASI Vocabulary subtest, and BNT. The sample consisted of 468 community-dwelling adults aged 50–84 years. Outcomes & Results: Short forms consisted of 32 items for the PPVT-R, 15 items for WASI Vocabulary, and 20 items for BNT. Correlation coefficients between full and short forms ranged between .95 and .97. Total rate of inconsistent classification of persons with very low scores (lower than 2 SD below the population mean) based on the short forms was less than 3%, highlighting adequate potential sensitivity for clinical purposes. The equivalence of the two versions of each test was further attested by similar patterns of relationships with demographic variables. Indices of internal consistency and test–retest reliability were very good for each of the three tests. Finally, the sensitivity of the short forms of each test for detecting lexical/semantic deterioration as a function of systemic diseases is discussed.

Verbal Comprehension Ability in Aphasia: Demographic and Lexical Knowledge Effects

Background. Assessment of sentence-level auditory comprehension can be performed with a variety of tests varying in response requirements. A brief and easy to administer measure, not requiring an overt verbal or a complex motor response, is essential in any test battery for aphasia. Objective. The present study examines the clinical utility of receptive language indices for individuals with aphasia based on the Comprehension of Instructions in Greek (CIG), a variant of the Token Test, and the Greek version of PPVT-R. Methods. Normative data from a large community sample of Greek adults aged 46–80 years was available on both measures. A word-level-independent measure of auditory comprehension was computed as the standard score difference between the two tests and used to compare patients with and without comprehension deficits as indicated by their Boston Diagnostic Aphasia Examination profile. Results and Conclusions. Indices of internal consistency and test-retest reliability were very good. Education and age effects on performance were significant, with the former being stronger. The potential clinical utility of differential ability indices (contrasting sentence- and word-level auditory comprehension tests) is discussed.

The unbridged gap between clinical diagnosis and contemporary research on aphasia: A short discussion on the validity and clinical utility of taxonomic categories

HIGHLIGHTSThis study assessed the validity and clinical utility of the traditional aphasia classification.The traditional lesion‐to‐syndrome correspondence was not confirmed for 63.5% of patients.We also noted that an important proportion aphasic patients remained unclassified.Overall, we suggest a deficit‐rather than a syndrome‐based approach. ABSTRACT Even if the traditional aphasia classification is continuously questioned by many scholars, it remains widely accepted among clinicians and included in textbooks as the gold standard. The present study aims to investigate the validity and clinical utility of this taxonomy. For this purpose, 65 left‐hemisphere stroke patients were assessed and classified with respect to aphasia type based on performance on a Greek adaptation of the Boston Diagnostic Aphasia Examination. MRI and/or CT scans were obtained for each patient and lesions were identified and coded according to location. Results indicate that 26.5% of the aphasic profiles remained unclassified. More importantly, we failed to confirm the traditional lesion‐to‐syndrome correspondence for 63.5% of patients. Overall, our findings elucidate crucial vulnerabilities of the neo‐associationist classification, and further support a deficit‐rather than a syndrome‐based approach. The issue of unclassifiable patients is also discussed.

The dichotomous view on IFG lesion and non-fluent aphasia

A lesion in inferior frontal gyrus (IFG) is traditionally considered to be crucial for the occurrence of non-fluent aphasia. However, recent studies question the axiomatic causality between a lesion in this area and the expected non-fluent aphasic syndrome. The aim of the present study is to investigate the relationship between IFG lesions and non-fluent aphasia. To address this question, we present radiological and neuropsychological data of 49 chronic aphasic patients. Lesions were identified based on CT and/or MRI scans. Aphasia was assessed using the Boston Diagnostic Aphasia Examination-short form. Analysis indicated a statistically significant association between IFG lesion and non-fluent aphasic disturbances. Nevertheless, a large proportion of our patients did not confirm the traditional prediction, namely that non-fluent patients’ lesions would include the inferior frontal gyrus and the opposite would be true for fluent patients. Our results stress the importance of taking into account the size of particular estimates when conducting group analyses. We also argue in favor of examining individual data in clinical practice, and further suggest that the traditional lesion to syndrome correspondence seems to be oversimplified and should be thoroughly revisited.