Historically, the insula was considered primary gustatory cortex. Now it is known to play a more comprehensive role in the processing of sensory information, including acting as primary cortex for interoceptive information, including autonomic nervous system mediated changes. As such, it is critical for emotional feeling in accord with the James-Lange theory, a role previously ascribed to the limbic system. Neuroimaged abnormal grey matter volumes or activity levels in the insula have been associated with schizophrenia, eating disorders, anxiety and mood disorders, conduct disorder, autism, addiction, and chronic pain. The significance of these abnormal activity patterns remains theoretical. Neuropsychological studies have linked dominant insula injury with various symptoms of aphasia, but its exact role in language processing remains uncertain as most cases involve lesions that extend into perisylvian language zones. Functional neuroimaging studies have found insula hyper-activations, typically in conjunction with anterior cingulate cortex, for all manner of experimental tasks including those involving perception, intentional action, and consciousness. Such neuroimaged activity is unlikely to be task-specific, but rather reflective of generic changes in autonomic activity in response to salience, homeostatic incongruence, or cognitive challenge.

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Bilingualism has been reported to delay the age of retrospective report of first symptom in dementia. This study determined if the age of clinically diagnosed Alzheimer's disease and vascular dementia occurred later for bilingual than monolingual, immigrant and U.S. born, Hispanic Americans. It involved a secondary analysis of the subset of 81 bi/monolingual dementia cases identified at yearly follow-up (1998 through 2008) using neuropsychological test results and objective diagnostic criteria from the Sacramento Area Latino Study on Aging that involved a random sampling of community dwelling Hispanic Americans (N = 1789). Age of dementia diagnosis was analyzed in a 2 × 2 (bi/monolingualism × immigrant/U.S. born) ANOVA that space revealed both main effects and the interaction were non-significant. Mean age of dementia diagnosis was descriptively (but not significantly) higher in the monolingual (M = 81.10 years) than the bilingual (M = 79.31) group. Overall, bilingual dementia cases were significantly better educated than monolinguals, but U.S. born bilinguals and monolinguals did not differ significantly in education. Delays in dementia symptomatology pertaining to bilingualism are less likely to be found in studies: (a) that use age of clinical diagnosis vs. retrospective report of first dementia symptom as the dependent variable; and (b) involve clinical cases derived from community samples rather than referrals to specialist memory clinics.

Recent studies in the United States indicate that some neurologically intact minority groupings perform well below White Americans on neuropsychological tests. This has sparked the production of race-norms, especially for African Americans, that seek to reduce false positive rates (i.e., neurologically intact individuals misdiagnosed with cognitive impairment) in neuropsychological assessments. There are problems with this enterprise including: possible justification for inferior/superior treatment of different racial groupings; unknown effects on false negative rates (i.e., cognitive deficit misdiagnosed as normal); the overlooking of factors possibly responsible for group racial differences (e.g., acculturation); non-scientific and non-operational definitions of race/ethnic groupings; and an impossibly large number of potential race/ethnic groupings for which to generate race-norms. An alternative approach is to use a single set of combined race/ethnic norms and estimate preexisting neuropsychological skill levels by using individual comparison standards. This alternative has been poorly researched, a situation that needs correcting.

Problems associated with the use of culture and ethnicity as independent variables in neuropsychological assessment research are reviewed. Culture and ethnicity are complex multidimensional constructs that have defied operational definition. There are no clear criteria for separating cultural and ethnic groups. Cognitive differences between culture and ethnic groups encourage speculations of cultural or ethnic superiority and race-norming. An alternative approach is to focus upon measurable psychological variables that differ between cultural and ethnic groups and potentially impact neuropsychological test scores. To illustrate, research with Hispanic Americans is reviewed to show that English language fluency, length of residence within the United States, years of education, and persistence of poverty all impact test performance.