The role of acculturation in neuropsychological functioning has been realized with a variety of diverse populations, including individuals with schizophrenia (Chen, Lam, Chen, & Nguyen, 1996; Karno & Jenkins, 1993), AIDS patients (Maj et al., 1993, 1994a, 1994b), and dementia (Jacobs et al., 1997; Loewen-stein, Rubert, Arguelles, & Duara, 1995; Mahurin, Espino, & Hollifield, 1992). Of these, dementias have probably received the most attention and, thus, might reveal the most critical aspects of culture and educational attainment in individuals of a minority status.
The effects of culture on neuropsychological function has basically focused on Hispanics. This ethnic group is expected to reflect anywhere between 33 and 38% of the population of the United States growth projected to occur between 1990 and the year 2020 (Campbell, 1994). In fact, between 1979 and 1980, Hispanics over the age of 65 grew by over 75% (Cuellar, 1990). Initial studies tended to focus on the use of screening measures for this population (Glosser et al., 1993; Loewenstein, Arguelles, Barker, & Duara, 1993; Mahurin et al., 1992; Taussig, Henderson, & Mack, 1992). A common finding across studies is that Hispanic elderly perform at a lower level on most screening measures. Further, this effect is more pronounced when the individual is either nonacculturated or of low educational attainment. Further, these authors suggest that possibly the use of nonverbal tests might be of greater value, and they intuitively have less cultural weight attached to them. In addition, others have recommended that analysis of neuropsychological dysfunction be based on more functional tests, such as observation of actual behavior in a home setting (Loewenstein, Ardila, Roselli, Hayden & Eisdorfer, 1992; Loewenstein et al., 1995).
In some studies, acculturation has been controlled statistically. However, other problems arise. For example, sample selections have not allowed for adequate generalization. One illustration of this is the use of Hispanics as a unified or cohesive ethnic group when Hispanics reflect a heterogeneous population. Indeed in attempting to establish proverbs for a Spanish translation of the WISC, a panel of experts from different countries of Latin America, consensus could not be reached over a proverb that was universal to all different Hispanic groups. To compensate for these problems, Jacobs et al. (1997) de signed a study that controlled most of these confounds. Of the 14 measures used, Hispanic elderly scored poorer on 5 of the 14 measures. Surprisingly, most of these measures were nonverbal (i.e., Identities and Oddities, Benton Visual Retention Test matching (BVRT), and recognition. After obtaining these findings, the authors then grouped individuals according to three different acculturation groups. Acculturation was measured according to ease or fluidity of the English language. The three groups include adapted Hispanics (those that spoke good or very good English), a second group that was not acculturated (spoke little or no English), and a group that were native English speakers. The three groups were equal in terms of age and educational attainment. The results indicated that no differences were found between either the acculturated Hispanics or the English speakers. However, differences were noted between the non-acculturated Hispanics and the English speakers. Based on these findings, Jacobs's team is now exploring whether elderly Hispanics have different processing capabilities on geometric figures since that is the foundation of the BVRT.
Ostrovski-Solis et al. (1998) have chosen not to control but to manipulate educational attainment in neuropsychological test situations. She and her colleagues have found that educational level and acculturation has a negatively accelerated curve that eventually stabilizes or plateaus. Some neuropsychological tests, such as comprehension of language or verbal fluidity, are affected by as little as one to 2 years of formal education. Various hypotheses have been proposed by Ostrovski-Solis and colleagues, including the limited number of occasions that illiterate individuals come in contact with tests, the lack of familiarity with test protocol and performance (e.g., time), and, most likely, that education affects cerebral organization.
An excellent example of this type of study is found with the previously described WHO studies on AIDS patients (Maj et al., 1993,1994a, 1994b). One of the more interesting results is found when comparing asymptotic HIV-1 zero-positive and HIV-1-zero-negative controls in Kinshaha and Sao Paolo. These two groups, as compared to the other locations, perform worse, regardless of HIV status of their counterparts. In another instance, Maj et al. (1994b) reported that in Kinshasa and Nairobi, decreased functioning on neuropsychological tests was only evident in individuals with a very limited (versus high levels) of education. Maj et al. (1994b) have hypothesized that high levels of education augment a "cerebral reserve" potentiating cerebral circuits and synaptic connections. In addition, low educational attainment appears highly correlated with the prevalence of other medical problems including, but not limited to, infectious diseases and malnutrition as well as with morbidity. In other words, illiteracy, again, appears to equate, in one fashion or another, with brain dysfunction.
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