Perceived Discrimination, Nativity, and Cognitive Performance in a Multi-ethnic Study of Older Adults: Findings from the Kaiser Healthy Aging and Diverse Life Experiences (KHANDLE) Study

BACKGROUND

Despite growing research on the association between discrimination and disparities in cognitive aging, an evidence gap remains on how the association varies by racial/ethnic group. This study evaluates the associations of experiences of discrimination with cognitive function and whether these associations varied by race/ethnicity and nativity.

METHODS

Using the Kaiser Healthy Aging and Diverse Life Experiences (KHANDLE) cohort (N=1,712) with approximately equal groups of Black, White, Latino, and Asian community-dwelling older adults aged 65 years and older, we evaluated the associations between self-reported experiences of everyday and major lifetime discrimination with overall cognitive performance and domain-specific cognition (verbal episodic memory, semantic memory and executive functioning) across race/ethnicity and nativity. Linear regression models examined the cross-sectional association between self-reported experiences of everyday and major lifetime discrimination with z-standardized coefficients for cognition. We tested for effect modification by race and nativity. All models controlled for age, sex and education.

RESULTS

Among KHANDLE participants (mean age: 76 years; standard deviation: 6.8), everyday discrimination was not associated with cognitive scores. Major lifetime discrimination was associated with better average cognitive scores among Black participants but not among other racial/ethnic groups. Major lifetime discrimination was associated with better average cognitive scores among US-born but not among non-US born individuals.

CONCLUSION

Our findings do not imply that discrimination improves cognition, but rather suggest that future research should include more detailed measures on discrimination and unfair treatment that could help disentangle the extent to which relationships are causal or reflect some other underlying factor.

Comparison of spectroscopic techniques for the determination of Kjeldahl and ammoniacal nitrogen content of farmyard manure

The feasibility of determining the nitrogen content of farmyard manure using infrared spectroscopy was investigated. Fifteen samples each of cattle, pig, and turkey manure were analyzed by three infrared techniques: Fourier transform mid-infrared (MIR), using attenuated total reflection (ATR); near-infrared reflectance (NIR-R); and near-infrared optothermal photoacoustic (NIR-OT). The near-infrared measurements were made at wavelengths determined respectively by four (NIR-OT) and five (NIR-R) band-pass filters. The total nitrogen (using the Kjeldahl method) and volatile (ammoniacal) nitrogen contents of all samples were measured by wet chemistry. Internally cross-validated (ICV) partial least-squares (PLS) regression was then used to obtain calibrations for the nitrogen content. The data sets obtained by each technique were treated separately. Within these sets, data from each manure type were treated both separately and combined: the best predictive ability was obtained by combining data from all three manure types. From the combined data set, the residual standard deviations and correlation coefficients for the ICV-predicted versus actual Kjeldahl nitrogen content were, respectively, 6772 mg/kg dry wt, 0.862 (MIR); 9434 mg/kg dry wt, 0.771 (NIR-OT); and 8943 mg/kg dry wt, 0.865 (NIR-R). For the ammoniacal nitrogen content, the residual standard deviations and correlation coefficients were 3869 mg/kg dry wt, 0.899 (MIR); 6079 mg/kg dry wt, 0.820 (NIR-OT); and 3498 mg/kg dry wt, 0.961 (NIR-R).

A rapid whole-blood immunoassay system

A new immunoassay system has been developed which allows the detection of circulating antigens, antibodies or drugs in whole blood without specialized personnel or equipment. This is achieved by the use of bispecific reagents, which comprise specific antibodies or antigens that are coupled to a non-agglutinating antierythrocyte antibody. Within two minutes, these reagents cause specific agglutination of a patient's own red cells in samples that contain the relevant analyte. Levels of low molecular weight haptens also can be measured by the use of an indirect, agglutination-inhibition assay. This simple immunoassay method would fulfil the needs of many physicians and Third-World countries and also has mass-screening and veterinary applications.

Genetic observations on the taxon Anopheles (Cellia) pharoensis Theobald (Diptera: Culicidae)

A photomap of the ovarian polytene chromosomes from Anopheles pharoensis is presented. The arrangement shown is that found in populations from Zululand, South Africa, and represents the arbitrary standard for the taxon. Two X-chromosome arrangements exist in samples from allopatric natural populations. Crosses between females homozygous for the inverted arrangement, Xa, and males carrying the standard arrangement, X+a, give F1 males that are sterile. Females from this cross, and both males and females from the reciprocal cross, are fertile. The simplest hypothesis is that the two X-chromosome arrangements mark two species within the taxon An. pharoensis Theobald. The practical implications are briefly discussed.

Fenitrothion (OMS 43) resistance in the taxon Anopheles culicifacies Giles

Two colonies of the taxon Anopheles culicifacies Giles (one from Maharashtra State and one from Gujarat State, India) produced 28 and 64% mortality rates, respectively, on 1% fenitrothion for 2 hours. Six-hour exposures were required to achieve mortalities of greater than or equal to 96% in both colonies.

Unidirectional hybrid male sterility from crosses between species A and species B of the taxon Anopheles (Cellia) culicifacies Giles

Crosses between species A females and species B males of the taxon Anopheles culicifacies give F1 males with undeveloped testes, reduced vasa deferentia, and apparently normal accessory glands. F1 males from the reciprocal cross, and F1 hybrid females from both reciprocal crosses are fertile, though their fertility is less than that of either parental species

Chromosomal evidence for sibling species of the malaria vector Anopheles (Cellia) culicifacies Giles

The ovarian polytene chromosomes of adult Anopheles culicifacies from natural populations in Pakistan, India and Sri Lanka, and from four laboratory colonies (one from Pakistan and three from India) are compared with the published cytological map for this taxon. Two types of X-chromosome exist. One of these is identical with the published map; the other differs by two inversions. No autosome arm rearrangements are detected. A photomap is presented which documents the X-chromosome inversions. Both types of Xs are found in a natural population near New Delhi in the apparent absence of heterozygotes. This is interpreted as evidence for biologically distinct species within the taxon An. culicifacies Giles. The formal taxonomic and practical implications are briefly discussed.

Laboratory evidence for mate recognition behaviour in a member of the Culex pipiens Complex (Diptera : Culicidae)

Assortative mating between the mosquito taxon Culex pipiens variety molestus and both Culex fatigans and C. globocoxitus is examined in laboratory choice experiments by use of alcohol dehydrogenase allozymes, detected by gel electrophoresis, as genetic markers. Complete positive assortative mating results when molestus males are present with both sexes of either C. fatigans or C. globocoxitus. This is interpreted as due to the operation of different systems of mate recognition. The existence of mate recognition systems governing the complete positive assortative mating which results when either C. fatigans or C. globocoxitus males are present with both sexes of molestus is masked by the effects of differential development. Mate recognition behaviour in molestus females is inferred, however, from the discrimination against molestus males by C. fatigans and C. globocoxitus females. A consequence of the different behaviours responsible for mate recognition is the prediction that molestus can coexist in nature with other members of the C. pipiens group of species with which it is interfertile in artificial crosses. This argues for the reinstatement of molestus as a full species.