David R Williams

Harvard Medical School, Boston, Massachusetts, United States

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Publications (484)1418.79 Total impact

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    ABSTRACT: Sinusoidal rectification (i.e., desinusoiding) is necessary for scanning imaging systems and is typically achieved by calculating a rectification transform from a calibration image such as a regular grid. This approach is susceptible to error due to electronic or mechanical instability that can alter the phase of the imaging window with respect to the calibration transform. Here, we show a calibration-free rectification method implemented from live video of a scanning light ophthalmoscope (SLO) with or without adaptive optics (AO). This approach, which capitalizes on positional differences in the images obtained in the forward and backward scan directions, dynamically keeps the imaging window in phase with the motion of the sinusoidal resonant scanner, preventing errors from signal drift over time. A benefit of this approach is that it allows the light power across the field-of-view (FOV) to be modulated inversely to achieve uniform irradiance on the retina, a feature desirable for functional imaging methods and light safety in SLOs.
    Optics letters. 01/2015; 40(1):85-88.
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    ABSTRACT: Background Previous research suggests that many people receiving mental health treatment do not meet criteria for a mental disorder but are rather 'the worried well'. Aims To examine the association of past-year mental health treatment with DSM-IV disorders. Method The World Health Organization's World Mental Health (WMH) Surveys interviewed community samples of adults in 23 countries (n = 62 305) about DSM-IV disorders and treatment in the past 12 months for problems with emotions, alcohol or drugs. Results Roughly half (52%) of people who received treatment met criteria for a past-year DSM-IV disorder, an additional 18% for a lifetime disorder and an additional 13% for other indicators of need (multiple subthreshold disorders, recent stressors or suicidal behaviours). Dose-response associations were found between number of indicators of need and treatment. Conclusions The vast majority of treatment in the WMH countries goes to patients with mental disorders or other problems expected to benefit from treatment.
    The British journal of psychiatry: the journal of mental science 11/2014; · 6.62 Impact Factor
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    ABSTRACT: IMPORTANCE: The inverse social gradient in mental disorders is a well-established research finding with important implications for causal models and policy. This research has used traditional objective social status (OSS) measures, such as educational level, income, and occupation. Recently, subjective social status (SSS) measurement has been advocated to capture the perception of relative social status, but to our knowledge, there have been no studies of associations between SSS and mental disorders. OBJECTIVES: To estimate associations of SSS with DSM-IV mental disorders in multiple countries and to investigate whether the associations persist after comprehensive adjustment of OSS. DESIGN, SETTING, AND PARTICIPANTS: Face-to-face cross-sectional household surveys of community-dwelling adults in 18 countries in Asia, South Pacific, the Americas, Europe, and the Middle East (N = 56 085). Subjective social status was assessed with a self-anchoring scale reflecting respondent evaluations of their place in the social hierarchies of their countries in terms of income, educational level, and occupation. Scores on the 1 to 10 SSS scale were categorized into 4 categories: low (scores 1-3), low-mid (scores 4-5), high-mid (scores 6-7), and high (scores 8-10). Objective social status was assessed with a wide range of fine-grained objective indicators of income, educational level, and occupation. MAIN OUTCOMES AND MEASURES: The Composite International Diagnostic Interview assessed the 12-month prevalence of 16 DSM-IV mood, anxiety, and impulse control disorders. RESULTS: The weighted mean survey response rate was 75.2% (range, 55.1%-97.2%). Graded inverse associations were found between SSS and all 16 mental disorders. Gross odds ratios (lowest vs highest SSS categories) in the range of 1.8 to 9.0 were attenuated but remained significant for all 16 disorders (odds ratio, 1.4-4.9) after adjusting for OSS indicators. This pattern of inverse association between SSS and mental disorders was significant in 14 of 18 individual countries, and in low-, middle-, and high-income country groups but was significantly stronger in high- vs lower-income countries. CONCLUSIONS AND RELEVANCE: Significant inverse associations between SSS and numerous DSM-IV mental disorders exist across a wide range of countries even after comprehensive adjustment for OSS. Although it is unclear whether these associations are the result of social selection, social causation, or both, these results document clearly that research relying exclusively on standard OSS measures underestimates the steepness of the social gradient in mental disorders.
    JAMA Psychiatry 10/2014; · 12.01 Impact Factor
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    ABSTRACT: Purpose: Advances in retinal imaging have led to the discovery of long-lasting retinal changes, including disruption of the retinal pigment epithelium (RPE) caused by light exposures below published safety limits. To investigate the functional consequences of RPE disruption, we combined adaptive optics ophthalmoscopy with retinal densitometry. Methods: A modified adaptive optics scanning light ophthalmoscope (AOSLO) measured the apparent density and regeneration rate of rhodopsin in two macaques before and after 4 different 568 nm retinal radiant exposures (RREs, 400 - 3200 J/cm2). OCT was used to measure the optical path length through the photoreceptor outer segments before and after RPE disruption. Results: All tested RREs caused visible RPE disruption. Apparent rhodopsin density was significantly reduced following 1600 J/cm2 (p = 0.01) and 3200 J/cm2 (p = 0.007) exposures. No significant change in apparent density was observed in response to 800 J/cm2. Surprisingly, exposure to 400 J/cm2 showed a significant increase in apparent density (p = 0.047). Rhodopsin recovery rate was not significantly affected by these RREs. OCT measurements showed a significant decrease in the optical path length through the photoreceptor outer segments for RREs above 800 J/cm2 (p < 0.001). Conclusions: At higher RREs, optical path length through the outer segments was reduced. However, the rate of photopigment regeneration was unchanged. While some ambiguity remains as to the correlation between measured reflectivity and absolute rhodopsin density; at the lowest RREs, RPE disruption appears not to be accompanied by a loss of apparent rhodopsin density, which would have been indicative of functional loss.
    Investigative ophthalmology & visual science. 10/2014;
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    ABSTRACT: Purpose: Retinal densitometry provides objective information about retinal function. But, a number of factors, including retinal reflectance changes that are not directly related to photopigment depletion, complicate its interpretation. We explore these factors and suggest a method to minimize their impact. Methods: An adaptive optics scanning light ophthalmoscope (AOSLO) was used to measure changes in photoreceptor reflectance in monkeys before and after photopigment bleaching with 514 nm light. Reflectance measurements at 514 nm and 794 nm were recorded simultaneously. Several methods of normalization to extract the apparent optical density of the photopigment were compared. Results: We identified stimulus-related fluctuations in 794 nm reflectance that are not associated with photopigment absorptance and occur in both rods and cones. These changes had a magnitude approaching those associated directly with pigment depletion, precluding the use of infrared reflectance for normalization. We used a spatial normalization method instead, which avoided the fluctuations in the near infrared, as well as a confocal AOSLO designed to minimize light from layers other than the receptors. However, these methods produced a surprisingly low estimate of the apparent rhodopsin density (Animal 1: 0.073 ± 0.006, Animal 2: 0.032 ± 0.003). Conclusions: These results confirm earlier observations that changes in photopigment absorption are not the only source of retinal reflectance change during dark adaptation. It appears that the stray light that has historically reduced the apparent density of cone photopigment in retinal densitometry arises predominantly from layers near the photoreceptors themselves. Despite these complications, this method provides a valuable, objective measure of retinal function.
    Investigative ophthalmology & visual science. 10/2014;
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    ABSTRACT: To assess potential contributors to high injury rates and smoking prevalence among construction workers, we investigated the association of safety climate with personal protective equipment use, and smoking behaviors.
    Journal of occupational and environmental medicine / American College of Occupational and Environmental Medicine 10/2014; 56(10):1082-1087. · 1.88 Impact Factor
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    ABSTRACT: Eye motion is a major impediment to the efficient acquisition of high resolution retinal images with the adaptive optics (AO) scanning light ophthalmoscope (AOSLO). Here we demonstrate a solution to this problem by implementing both optical stabilization and digital image registration in an AOSLO. We replaced the slow scanning mirror with a two-axis tip/tilt mirror for the dual functions of slow scanning and optical stabilization. Closed-loop optical stabilization reduced the amplitude of eye-movement related-image motion by a factor of 10–15. The residual RMS error after optical stabilization alone was on the order of the size of foveal cones: ~1.66–2.56 μm or ~0.34–0.53 arcmin with typical fixational eye motion for normal observers. The full implementation, with real-time digital image registration, corrected the residual eye motion after optical stabilization with an accuracy of ~0.20–0.25 μm or ~0.04–0.05 arcmin RMS, which to our knowledge is more accurate than any method previously reported.
    Biomedical Optics Express 09/2014; 5(9). · 3.18 Impact Factor
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    ABSTRACT: Despite higher rates of prostate cancer-related mortality and later stage of prostate cancer diagnosis, Black/African American men are significantly less likely than non-Hispanic White men to use early detection screening tools, like prostate-specific antigen (PSA) testing for prostate cancer. Lower screening rates may be due, in part, to controversy over the value of prostate cancer screenings as part of routine preventive care for men, but Black men represent a high-risk group for prostate cancer that may still benefit from PSA testing. Exploring the role of social factors that might be associated with PSA testing can increase knowledge of what might promote screening behaviors for prostate cancer and other health conditions for which Black men are at high risk. Using multilevel logistic regression, this study analyzed self-report lifetime use of PSA test for 829 Black men older than 45 years across 381 Philadelphia census tracts. This study included individual demographic and aggregated social capital data from the Public Health Management Corporation's 2004, 2006, and 2008 waves of the Community Health Database, and sociodemographic characteristics from the 2000 U.S. Census. Each unit increase in community participation was associated with a 3 to 3.5 times greater likelihood of having had a PSA test (odds ratio = 3.35). Findings suggest that structural forms of social capital may play a role in screening behaviors for Black men in Philadelphia. A better understanding of the mechanism underlying the link between social capital and screening behaviors can inform how researchers and interventionists develop tools to promote screening for those who need it.
    American journal of men's health 08/2014; · 1.15 Impact Factor
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    ABSTRACT: Both mental and physical disorders can result in role limitation, such as 'days out of role', which have an important impact on national productivity losses. This paper analyses data from the South African Stress and Health Study (SASH) on the association of both mental and physical disorders with days out of role.
    Social Psychiatry and Psychiatric Epidemiology 08/2014; · 2.86 Impact Factor
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    ABSTRACT: Purpose To examine whether allostatic load (AL), a measure of cumulative physiologic dysregulation across biological systems, was associated with sleep apnea, insomnia, and other sleep disturbances. Methods Data from the National Health and Nutrition Examination Survey 2005-2008 were used. AL was measured using nine biomarkers representing cardiovascular, inflammatory, and metabolic system functioning. A total of 7,726 US adults aged 18 years and older were included in this study. Results The prevalence of high AL (AL score ≥3) was the highest among African Americans (25.2%), followed by Hispanic Americans (21.0%), Whites (18.8%), and other racial/ethnic group (16.5%). After adjustment for sociodemographic and lifestyle factors and depression status, high AL was significantly associated with sleep apnea (odds ratio (OR)=1.49, 95% confidence interval (CI): 1.14-1.95), snoring (1.65, 95% CI: 1.41-1.93), snorting/stop breathing (OR=1.62, 95% CI: 1.25-2.10), prolonged sleep latency (OR=1.33, 95% CI: 1.13-1.56), short sleep duration (<6 hours) (OR=1.29, 95% CI: 1.04-1.61), and diagnosed sleep disorder (OR=1.85, 95% CI: 1.53-2.24). There was no clear evidence that observed associations varied by sociodemographic characteristics or depression status. Conclusions This study suggests significant associations of high AL with sleep apnea, sleep apnea symptoms, insomnia component, short sleep duration, and diagnosed sleep disorder among US adults.
    Annals of Epidemiology 08/2014; · 2.48 Impact Factor
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    ABSTRACT: Purpose: Noninvasive two-photon imaging of a living mammallian eye can reveal details of molecular processes in the retina and retinal pigmented epithelium (RPE). Retinyl esters and all-trans-retinal condensation products are two types of retinoid fluorophores present in the retina and RPE. We compared the content of these two types of retinoids in mouse, monkey, and human eyes to validate the potential of two-photon imaging for monitoring retinoid changes in human eyes. Methods: Two-photon microscopy (TPM) was used to visualize the retina in excised retina from monkey eyes. Retinoid composition and content in human and monkey eyes were quantified by high performance liquid chromatography (HPLC) and mass spectrometry (MS). Results: Clear images of inner and outer segments of rods and cones were obtained in primate eyes at different eccentricities. Fluorescence spectra from outer segments revealed a maximum emission at 480 nm indicative of retinols and their esters. In cynomolgus monkey and human retinal extracts, retinyl esters existed predominantly in the 11-cis configuration along with notable levels of 11-cis-retinol, a characteristic of cone-enriched retinas. Average amounts of A2E in primate and human eyes were 160 pmol/eye and 225 pmol/eye, respectively. Conclusions: Our data show that human retina contains sufficient amounts of retinoids for two-photon excitation imaging. Greater amounts of 11-cis-retinyl esters relative to rodent retinas contribute to fluorescence signal from both monkey and human eyes. These observations indicate that TPM imaging found effective in mice can also be used to track early age- and disease-related changes in human retina.
    Investigative ophthalmology & visual science. 06/2014;
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    ABSTRACT: Two-photon excitation microscopy can image retinal molecular processes in vivo. Intrinsically fluorescent retinyl esters in subcellular structures called retinosomes are an integral part of the visual chromophore regeneration pathway. Fluorescent condensation products of all-trans-retinal accumulate in the eye with age and are also associated with age-related macular degeneration (AMD). Here, we report repetitive, dynamic imaging of these compounds in live mice through the pupil of the eye. By leveraging advanced adaptive optics, we developed a data acquisition algorithm that permitted the identification of retinosomes and condensation products in the retinal pigment epithelium by their characteristic localization, spectral properties and absence in genetically modified or drug-treated mice. This imaging approach has the potential to detect early molecular changes in retinoid metabolism that trigger light- and AMD-induced retinal defects and to assess the effectiveness of treatments for these conditions.
    Nature Medicine 06/2014; · 22.86 Impact Factor
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    ABSTRACT: Objective. To examine racial-ethnic differences in the endorsement and attribution of psychotic-like symptoms in a nationally representative sample of African-Americans, Asians, Caribbean Blacks, and Latinos living in the USA. Design. Data were drawn from a total of 979 respondents who endorsed psychotic-like symptoms as part of the National Latino and Asian American Study (NLAAS) and the National Survey of American Life (NSAL). We use a mixed qualitative and quantitative analytical approach to examine sociodemographic and ethnic variations in the prevalence and attributions of hallucinations and other psychotic-like symptoms in the NLAAS and NSAL. The lifetime presence of psychotic-like symptoms was assessed using the World Health Organization Composite International Diagnostic Interview (WMH-CIDI) psychotic symptom screener. We used logistic regression models to examine the probability of endorsing the four most frequently occurring thematic categories for psychotic-like experiences by race/ethnicity (n > 100). We used qualitative methods to explore common themes from participant responses to open ended questions on their attributions for psychotic-like symptoms. Results. African-Americans were significantly less likely to endorse visual hallucinations compared to Caribbean Blacks (73.7% and 89.3%, p < .001), but they endorsed auditory hallucinations symptoms more than Caribbean Blacks (43.1% and 25.7, p < .05). Endorsing delusions of reference and thought insertion/withdrawal were more prevalent for Latinos than for African-Americans (11% and 4.7%, p < .05; 6.3% and 2.7%, p < .05, respectively). Attribution themes included: supernatural, ghosts/unidentified beings, death and dying, spirituality or religiosity, premonitions, familial and other. Respondents differed by race/ethnicity in the attributions given to psychotic like symptoms. Conclusion. Findings suggest that variations exist by race/ethnicity in both psychotic-like symptom endorsement and in self-reported attributions/understandings for these symptoms on a psychosis screening instrument. Ethnic/racial differences could result from culturally sanctioned beliefs and idioms of distress that deserve more attention in conducting culturally informed and responsive screening, assessment and treatment.
    Ethnicity & health. 06/2014;
  • Ronica N. Rooks, Yanmei Xu, David R. Williams
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    ABSTRACT: We examined the relationship between neighborhood environment (e.g., objective neighborhood socioeconomic status [SES] and subjective neighborhood perceptions) and waist-hip ratio (WHR) or central obesity using logistic regression and content analysis of respondents’ narratives on housing unfair treatment in the YES Health pilot study. Multivariate results showed significant relationships between low SES White, low SES Black, and middle SES Black versus middle SES White neighborhoods and total-sample and women's obesity, in almost all neighborhood perception models. Significant relationships included: disliking neighborhood and total-sample obesity; neighborhood informal monitoring/surveillance and total-sample and women's obesity; social participation and total-sample and women's obesity; and perceptions of families and total-sample and women's obesity. Qualitative results partially corroborate our quantitative results that low SES neighborhood adults were more likely to experience neighborhood disorders and safety issues. Our findings highlight examining objective and subjective neighborhood environments related to central obesity, suggesting specific health targets for neighborhood intervention programs.
    Journal of Social Issues 06/2014; 70(2). · 1.96 Impact Factor
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    ABSTRACT: Although Black-white differences in depression are well documented, vigilant coping style as an explanation for the observed inequalities in depression is less understood. Using data from 718 adults in the Exploring Health Disparities in Integrated Communities (EHDIC) Study, we estimated logistic regression models to examine the cross sectional relationship between race, vigilant coping style, and depression. After controlling for demographic variables, white adults were more likely to report depression than Black adults. Moreover, when accounting for coping style, the Black-white difference in depression widened. This association persisted even with the addition of the covariates. While high rates of depression among whites compared with Blacks are well documented, the degree of the differences appears to be greater than previously reported once vigilance is accounted for. This finding suggests that if it were not for the high prevalence of vigilant coping in blacks, the well-documented black advantage regarding depression compared to whites would likely be even greater.
    Journal of Social Issues 06/2014; 70(2):241-255. · 1.96 Impact Factor
  • David R Williams, Akshay A Shah
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    ABSTRACT: Studies describe the total synthesis of (+)-ileabethoxazole (1) using a Stille cross-coupling reaction of propargylic stannanes with 5-iodo-1,3-oxazoles to produce 1,1-disubstituted allenes (11). An iron-mediated [2+2+1] carbocyclization yields a novel cyclopentenone for elaboration to 1. Site-selective palladium insertion reactions allow for regiocontrolled substitutions of the heterocycle. Asymmetric copper hydride reductions are examined, and strategies for the formation of the central aromatic ring are discussed.
    Journal of the American Chemical Society 05/2014; · 10.68 Impact Factor
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    ABSTRACT: Purpose Many retinal imaging instruments utilize infrared wavelengths to reduce the risk of light damage. However, we have discovered that exposure to infrared illumination causes a long-lasting reduction in infrared autofluorescence (IRAF). We have characterized the dependence of this effect on radiant exposure and investigated its origin. Methods A scanning laser ophthalmoscope was used to obtain IRAF images from two macaques before and after exposure to 790 nm light (15-450 J/cm2). Exposures were performed with either raster-scanning or uniform illumination. IRAF images were also obtained in two humans exposed to 790 nm light in a separate study. Humans were assessed with direct ophthalmoscopy, Goldmann visual fields, multifocal ERG, and photopic microperimetry to determine whether these measures revealed any effects in the exposed location. Results A significant decrease in IRAF after exposure to infrared light was seen in both monkeys and humans. In monkeys, the magnitude of this reduction increased with retinal radiant exposure. Partial recovery was seen at one month with full recovery within 21 months. Consistent with a photochemical origin, IRAF decreases caused by either raster-scanning or uniform illumination were not significantly different. We were unable to detect any effect of the light exposure with any measure other than IRAF imaging. We cannot exclude the possibility that changes could be detected with more sensitive tests or longer follow-up. Conclusions This long lasting effect of infrared illumination in both humans and monkeys occurs at exposure levels 4-5 times below current safety limits. The photochemical basis for this phenomenon remains unknown.
    Investigative ophthalmology & visual science. 05/2014;
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    ABSTRACT: The fovea dominates primate vision, and its anatomy and perceptual abilities are well studied, but its physiology has been little explored because of limitations of current physiological methods. In this study, we adapted a novel in vivo imaging method, originally developed in mouse retina, to explore foveal physiology in the macaque, which permits the repeated imaging of the functional response of many retinal ganglion cells (RGCs) simultaneously. A genetically encoded calcium indicator, G-CaMP5, was inserted into foveal RGCs, followed by calcium imaging of the displacement of foveal RGCs from their receptive fields, and their intensity-response functions. The spatial offset of foveal RGCs from their cone inputs makes this method especially appropriate for fovea by permitting imaging of RGC responses without excessive light adaptation of cones. This new method will permit the tracking of visual development, progression of retinal disease, or therapeutic interventions, such as insertion of visual prostheses.
    Journal of Neuroscience 05/2014; 34(19):6596-605. · 6.91 Impact Factor
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    ABSTRACT: Objective Analyses test the hypothesis that aspects of social relationships (quantity of ties, social support and social strain) are associated with differences in levels of biological risk across multiple major physiological regulatory systems and consequently overall multi-systems risk (i.e., allostatic load [AL]). Methods Data are from the Coronary Artery Risk Development in Young Adults (CARDIA) study - a bi-ethnic, prospective, multi-center epidemiological study, initiated in 1985-86 to track the development of cardiovascular risk in young adulthood (N = 5,115). At the year 15 follow-up when participants were between 32-45 years of age, additional social and biological data were collected; biological data used to assess AL were collected at the Oakland, CA and Chicago, IL sites (N = 844). Results Social strains were most strongly and positively related to overall AL (Cohen's d = .79 for highest vs. lowest quartile), and to each of its component biological subsystems, independent of social ties and support as well as sociodemographics and health behaviors. Social ties and emotional support were also negatively related to AL (Cohen's d = .33 and d = .44 for lowest vs. highest quartiles of ties and support, respectively) though controls for social strains reduced these associations to non-significance. Social support and social strain were more strongly related to overall AL than to any of its component subscales while social ties were less strongly related to AL and to its component subscales. There was no evidence that effects differed by sex, age or ethnicity. Conclusions Findings focus attention on the particularly strong relationship between social strains and profiles of biological risk and support the cumulative impact of social factors on biological risks, showing larger effects for cumulative AL than for any of the individual biological systems.
    Psychoneuroendocrinology 05/2014; · 5.59 Impact Factor
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    ABSTRACT: Despite a long history of discrimination and persisting racial disparities in smoking prevalence, little research exists on the relationship between discrimination and smoking in South Africa. This analysis examined chronic (day-to-day) and acute (lifetime) experiences of racial and non-racial (eg, age, gender or physical appearance) discrimination and smoking status among respondents to the South Africa Stress and Health study. Logistic regression models were constructed using SAS-Callable SUDAAN. Both chronic racial discrimination (RR=1.45, 95% CI 1.14 to 1.85) and chronic non-racial discrimination (RR=1.69, 95% CI 1.37 to 2.08) predicted a higher risk of smoking, but neither type of acute discrimination did. Total (sum of racial and non-racial) chronic discrimination (RR=1.46, 95% CI 1.20 to 1.78) and total acute discrimination (RR=1.28, 95% CI 1.01 to 1.60) predicted a higher risk of current smoking. Racial and non-racial discrimination may be related to South African adults' smoking behaviour, but this relationship likely varies by the timing and frequency of these experiences. Future research should use longitudinal data to identify the temporal ordering of the relationships studied, include areas outside of South Africa to increase generalisability and consider the implications of these findings for smoking cessation approaches in South Africa.
    Tobacco control 04/2014; · 3.85 Impact Factor

Publication Stats

13k Citations
1,418.79 Total Impact Points


  • 2007–2014
    • Harvard Medical School
      • • Department of Medicine
      • • Department of Health Care Policy
      Boston, Massachusetts, United States
    • Kaiser Permanente
      Oakland, California, United States
    • Buskerud and Vestfold University College
      Tønsberg, Vestfold county, Norway
    • Wayne State University
      • Institute of Gerontology
      Detroit, MI, United States
  • 1993–2014
    • Indiana University Bloomington
      • Department of Chemistry
      Bloomington, Indiana, United States
  • 1985–2014
    • University of Rochester
      • • Institute of Optics
      • • Flaum Eye Institute
      • • Center for Visual Science
      • • Department of Electrical and Computer Engineering
      Rochester, New York, United States
  • 1977–2014
    • Harvard University
      • • Department of Society, Human Development, and Health
      • • Department of Psychology
      Cambridge, Massachusetts, United States
  • 2013
    • University of Haifa
      H̱efa, Haifa District, Israel
    • Massachusetts Department of Public Health
      Boston, Massachusetts, United States
  • 2011–2013
    • University of California, Berkeley
      • School of Optometry
      Berkeley, California, United States
    • Oakland University
      • Department of Health Sciences
      Rochester, MI, United States
    • Robert Wood Johnson Foundation
      Princeton, New Jersey, United States
  • 2008–2013
    • Yale University
      • Center for Interdisciplinary Research on AIDS (CIRA)
      New Haven, CT, United States
    • Idenix Pharmaceuticals, Inc.
      Cambridge, Massachusetts, United States
    • University of Colorado at Boulder
      • Institute of Behavioral Science (IBS)
      Boulder, CO, United States
    • University of Groningen
      • Department of Psychiatry
      Groningen, Province of Groningen, Netherlands
    • University of California, Davis
      Davis, California, United States
    • University of Wisconsin, Madison
      • Department of Population Health Sciences
      Madison, MS, United States
  • 1995–2013
    • University of Michigan
      • • Department of Epidemiology
      • • School of Social Work
      • • Institute for Social Research
      • • Department of Psychiatry
      • • Department of Sociology
      Ann Arbor, MI, United States
  • 2012
    • Jackson State University
      • School of Health Sciences
      Jackson, Mississippi, United States
    • Universitair Psychiatrisch Centrum KU Leuven
      Cortenberg, Flanders, Belgium
    • Boston Children's Hospital
      • Division of General Pediatrics
      Boston, MA, United States
    • University of Toronto
      Toronto, Ontario, Canada
    • University of South Carolina
      • Department of Epidemiology & Biostatistics
      Columbia, SC, United States
    • Luther College
      Decorah, Iowa, United States
  • 2008–2012
    • University of Cape Town
      • • Centre for Higher Education Development
      • • Department of Psychiatry and Mental Health
      Cape Town, Province of the Western Cape, South Africa
  • 2002–2012
    • George Washington University
      • Department of Psychology
      Washington, Washington, D.C., United States
    • University of Michigan-Dearborn
      Dearborn, Michigan, United States
    • University of Houston
      • College of Optometry
      Houston, TX, United States
    • Northwestern University
      Evanston, Illinois, United States
    • University of California, San Francisco
      • Veterans Affairs Medical Center
      San Francisco, CA, United States
  • 2010–2011
    • Groote Schuur Hospital
      Kaapstad, Western Cape, South Africa
    • University of Arkansas at Little Rock
      Little Rock, Arkansas, United States
    • Instituto Nacional de Psiquiatría
      Ciudad de México, The Federal District, Mexico
    • Yale-New Haven Hospital
      New Haven, Connecticut, United States
    • Ministry of Health (Israel)
      Yerushalayim, Jerusalem District, Israel
    • KU Leuven
      • Division of Psychiatry
      Leuven, VLG, Belgium
  • 2007–2011
    • Brigham and Women's Hospital
      • • Department of Medicine
      • • Division of General Internal Medicine and Primary Care
      Boston, MA, United States
  • 2009–2010
    • Stellenbosch University
      • Department of Psychiatry
      Stellenbosch, Province of the Western Cape, South Africa
    • Medical College of Wisconsin
      • Department of Ophthalmology
      Milwaukee, WI, United States
    • Union College
      New York City, New York, United States
    • University of Limpopo
      Pietersburg, Limpopo, South Africa
    • DePaul University
      Chicago, Illinois, United States
  • 2005–2010
    • Columbia University
      New York City, New York, United States
    • University of Kentucky
      Lexington, Kentucky, United States
    • Princeton University
      Princeton, New Jersey, United States
  • 2005–2009
    • University of Mississippi Medical Center
      • School of Medicine
      Jackson, MS, United States
  • 2004
    • Fundação Oswaldo Cruz
      Rio de Janeiro, Rio de Janeiro, Brazil
    • University of California, Santa Cruz
      • Center for Adaptive Optics
      Santa Cruz, CA, United States
  • 2003–2004
    • University of Murcia
      • Departamento de Física
      Murcia, Murcia, Spain
  • 2001–2004
    • University of Texas at Austin
      • Center for Population Research
      Texas City, TX, United States
  • 2000–2003
    • University of Pittsburgh
      • Department of Chemistry
      Pittsburgh, Pennsylvania, United States
  • 1998
    • Concordia University–Ann Arbor
      Ann Arbor, Michigan, United States