GENETICS AND HEALTH INEQUALITIES Johan Mackenbach Dept. of Public Health Erasmus MC
OUTLINE Socioeconomic inequalities in health in Europe: patterns and trends Explanations for socioeconomic inequalities in health: conventional wisdom Contribution of genetic factors: tentative hypotheses
SELF- REPORTED MORBIDITY BY EDUCATIONAL LEVEL
MORTALITY BY OCCUPATIONAL CLASS
CAUSES OF DEATH BY OCCUPATIONAL CLASS
TREND IN PERCEIVED GENERAL HEALTH BY INCOME LEVEL, MEN 25-69 YEARS 70 60 prevalence rate per 100 50 40 30 20 10 Germany lowest quintile Germany highest quintile England lowest quintile England highest quintile Netherlands lowest quintile Netherlands highest quintile 0 1980s period 1990s
TREND IN MORTALITY BY OCCUPATIONAL CLASS, MEN 30-59 YEARS 9 8 mortality rate per 1000 7 6 5 4 3 Finland manual Finland non-manual England manual England non-manual Sweden manual Sweden non-manual 2 1980-85 1990-1994 period
REVERSAL OF IHD MORTALITY BY SES Number of studies by association with socioeconomic status Consist Negative Unclear Consist positive Ischemic Heart Disease <1966 >1966 6 25 7 6 5 -
EXPLANATIONS OF HEALTH INEQUALITIES Selection and causation Material/psychosocial/behavior Life-course perspective
Selection and causation Socioeconomic status causation Health selection
Chronic conditions and downward social mobility (Odds Ratios x 100) 160 140 120 100 80 60 40 20 0 Down class Up class Out empl Into empl No chron cond Chron cond
Material/psychosocial/behavior Material factors Socioeconomic status Health behavior Health Psychosocial factors
180 160 140 120 100 80 60 40 20 0 Mortality (Relative Risk x 100) All causes CVD Cancer Other High edu 2 3 Low edu
Inequalities in smoking (age-adjusted %) 60 50 40 30 20 High educ 2 3 Low educ 10 0 Current Former Never
Inequalities in mortality: adjustment for mat/behavior 180 160 140 120 100 80 60 40 20 0 Confounders Behaviour Material Both High educ 2 3 Low educ
SMOKING BY EDUCATIONAL LEVEL
EDUCATIONAL RR S FOR LUNG CANCER MORTALITY IN NORWAY 4 3.5 3 2.5 2 1.5 1 0.5 40-49 50-59 60-69 70-79 80-89 0 Men Women
EDUCATIONAL RR S FOR LUNG CANCER MORTALITY IN MADRID 1.4 1.2 1 0.8 0.6 0.4 40-49 50-59 60-69 70-79 80-89 0.2 0 Men Women
PROPORTION OF EXCESS TOTAL DEATHS DUE TO SMOKING, MEN AND WOMEN 40-89 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0-0.1-0.2-0.3 Eng Nor Den Fin Bel Swi Aus Tur Bar Mad Men Women
Life-course perspective Childhood Adulthood Old age Socioeconomic status Socioeconomic status Socioeconomic status Intermediary factors Intermediary factors Intermediary factors Health Health Health
Father s social class, psychological attributes, and self-assessed health 250 200 150 100 50 High 2 Self-empl 4 Low 0 Confounders Psychological
ROLE OF GENOTYPE: CONSIDERATIONS (1) Genotype will play a role in explanation of socioeconomic inequalities in health: IF socioeconomic status is associated with a particular genotype, AND IF that genotype is associated with health, either directly or indirectly
ROLE OF GENOTYPE: CONSIDERATIONS (2) Socioeconomic status will be associated with genotype: IF genotype determines inter- or intragenerational social mobility (No need to assume intergenerational transmission of social class adherence)
INTERGENERATIONAL SOCIAL MOBILITY: SON S VS. FATHER S OCCUPATIONAL CLASS, NETHERLANDS, 1977 45 40 35 30 25 20 15 10 5 0 Intergen. social mobility Down Same Up
ROLE OF GENOTYPE: CONSIDERATIONS (2) Direct genetic risk factors for disease are unlikely to play more than incidental role, because: Disease-specific inequalities are variable across time, even within a generation, and Disease-specific inequalities are variable between populations
ROLE OF GENOTYPE: CONSIDERATIONS (3) However, genetic factors acting indirectly and generically might be more important, particularly factors that act as: determinants of health-related behavior AND determinants of social mobility such as cognitive ability (e.g. intelligence) and personality characteristics (e.g. neuroticism)
AVAILABLE EVIDENCE: INTELLIGENCE Intelligence is complex trait, multiple genes involved, far from elucidated Twin studies suggest heritability of 0.60 to 0.80 -- interpretation remains contested Intelligence is associated with educational achievement and health behavior Few studies on role of intelligence in health inequalities -- potentially important
FATHER S OCCUPATIONAL CLASS AND ADOLESCENT S SMOKING: CONTRIBUTION OF INTELLIGENCE 2.5 2 1.5 1 0.5 High 2 3 4 Low 0 Confounders Plus intelligence
AVAILABLE EVIDENCE: NEUROTICISM Neuroticism is complex trait, multiple genes involved, far from elucidated Twin studies suggest heritability of 0.20 to 0.40 -- interpretation remains contested Neuroticism is associated with social class and health outcomes Studies suggest role of neuroticism in inequalities in self-reported health
NEUROTICISM AND SELF- REPORTED HEALTH 8 7 6 5 4 3 2 1 0 Self-assessed health NHP-mobility Low 2 3 4 High
Hypothetical pathways Material and psychosocial factors Socioeconomic status Health behavior Health Intelligence Personality Genotype
CONCLUSIONS Explanations for socioeconomic inequalities in health correctly emphasize environmental factors Nevertheless, a role for genetic factors cannot be excluded, particularly in cognitive ability and personality Further research should be encouraged, but with a view to optimizing interventions