NORMATIVE DATA FOR FOUR NEUROPSYCHOLOGICAL TESTS IN A SAMPLE OF ADULTS WHO ARE ILLITERATE AND FROM LATIN AMERICA

NORMATIVE DATA FOR FOUR NEUROPSYCHOLOGICAL TESTS IN A SAMPLE OF ADULTS WHO ARE ILLITERATE AND FROM LATIN AMERICA By Alejandra Morlett Paredes, B.A., M.S. A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at Virginia Commonwealth University Virginia Commonwealth University, 2017 Director: Rosalie Corona, Ph.D. Associate Professor Department of Psychology Neuropsychological tests are standardized tasks used to measure psychological functioning that is associated with a particular brain structure. These tests often are used in diagnosing a cognitive deficiency resulting from brain injuries. Currently there are a limited number of studies that have focused on standardization of neuropsychological tests in Latin America. Therefore, the vast majority of cognitive tests used in the evaluation of patients with brain damage have no normative parameters adjusted to the cultural characteristics of Latinos and Latinas. As a result, neuropsychological diagnoses among this population may be inadequate, and evaluation of rehabilitation program effectiveness limited. The importance of culturally appropriate indices of neurological tests cannot be overstated; of all the problems presented by individuals with brain injuries, cognitive disorders are the leading source of disability for adequate work, family and social reintegration among this group. There is an urgent need to standardize neuropsychological tests in Latin America, among Latinos in the US and any other regions where neuropsychological test have not been standardized. An important population subgroup in Latin America severely lacking in norms for many neuropsychological tests are those deemed illiterate or unable to read or write. In Latin America, this group comprises approximately 31 million people over the age of 15. The living conditions and lifestyles of this vulnerable population can lead to more accidents and personal injury resulting in brain damage. Thus, this group is likely to experience neuropsychological trauma and is in need of appropriate diagnosis and treatment. The present dissertation focused on the standardization and validation of four widely used neuropsychological tests: the Rey–Osterrieth Complex Figure, the Wisconsin Card Sorting Test-Modified, the Semantic Verbal Fluency, and the Hopkins Verbal Learning Test-Revised. The results show that there was no multicollinearity between the predictor variables in the final models according to the tolerance and VIF values. Second, the majority of tests indicated homoscedasticity, except for the ROCF Memory and the M-WCST Correct Categories, for these tests the residual standard deviation (SDe) was estimated in each of the predictive scores quartiles in order to compensate for the lack of homoscedasticity in the model and to have greater precision in the generation of normative data. On the other hand the majority of the tests did not show a normal distribution (except for the M-WCST Total Errors, Animals, Fruits and the HVLT-R total recall), thus an empirical distribution function was used for the transformation of zi to percentile. Finally, influential values were not found in the final models of all tests. The final multiple linear regression models for the ROCF showed an effect of age for both the memory and copy tasks, showing a linear decline, as participants get older. However, the variables sex was only shown to be significant for the ROCF Copy, where older men had higher scores than older women. Regarding the M-WCST, the final multiple linear regression models revealed only an effect of age, for both Correct Categories and Total Errors, showing a linear decline of correct categories and an increase of errors, as subjects get older. It is important to note the final model for M-WCST Perseverations was not significant, thus normative data for this portion of the test was not developed. The Animals and Fruits categories of the semantic verbal fluency test had an effect of quadratic age, meaning a curvilinear increase in scores was observed up to approximately 50 years of age. A linear decline was only seen for the Professions category, where older people obtained lower scores than younger individuals. In addition, only the Fruits category showed an effect of sex, where women scored higher on this test than men. The final multiple linear regression models for the HVLT-R revealed a predictive effect of the variable age, for Total Recall, Delayed Recall and Recognition scores, showing a linear decline, as people get older. However, only the Total Recall scores showed a predictive effect for quadratic age, meaning a curvilinear increase in scores was observed up to approximately 50 years of age. Developing normative data for individuals who are illiterate will allow neuropsychologists to have a more accurate comparison when attempting to diagnose cognitive deficits among this group in Latin America. This dissertation is unique, as no other studies have looked at the normative data and standardization of neuropsychological tests within this population in Latin America.