Childhood IQ in relation to obesity and weight gain in adult life: the National Child Development (1958) Study

Psychomotor coordination and intelligence in childhood and health in adulthood--testing the system integrity hypothesis

OBJECTIVES

To examine associations between intelligence and psychomotor coordination in childhood and risk of psychological distress, poorer self-rated health, and obesity in adulthood. To investigate whether psychomotor coordination as a potential marker of the construct "system integrity" explains associations between intelligence and these outcomes.

METHODS

Participants were members of two British national birth cohorts: the 1958 National Child Development Survey (n = 6147) and the 1970 British Cohort Study (n = 6475). They took tests of psychomotor coordination and intelligence at age 10 to 11 years and reported on their health when in their early 30s.

RESULTS

For a standard deviation increase in psychomotor coordination score, sex-adjusted odds ratios (95% CI) for the 1958 and 1970 cohorts, respectively, were 0.79 (0.72-0.87) and 0.83 (0.77-0.89) for psychological distress, 0.79 (0.73-0.85) and 0.85 (0.78-0.91) for fair/poor self-rated health, and 0.81 (0.75-0.88) and 0.85 (0.78-0.92) for obesity. These associations were independent of childhood intelligence and most remained significant after adjustment for other covariates. Higher intelligence quotient was associated with a reduced risk of psychological distress, fair/poor self-rated health, and obesity in adulthood. These associations were not explained by potential confounding factors or by psychomotor coordination in childhood.

CONCLUSION

Having better psychomotor coordination in childhood seems protective for some aspects of health in adulthood. Examination of the role played by other markers of the efficiency of the central nervous system may help reveal the extent to which system integrity underlies the link between intelligence and health.

Aging, vascular risk, and cognition: blood glucose, pulse pressure, and cognitive performance in healthy adults

Advanced age is associated with decline in many areas of cognition as well as increased frequency of vascular disease. Well-described risk factors for vascular disease, such as diabetes and arterial hypertension, have been linked to cognitive deficits beyond those associated with aging. To examine whether vascular health indices such as fasting blood glucose levels and arterial pulse pressure can predict subtle deficits in age-sensitive abilities, the authors studied 104 healthy adults (ages 18 to 78) without diagnoses of diabetes or hypertension. Whereas results revealed a classic pattern of age-related differences in cognition, preprandial blood glucose level and pulse pressure independently and differentially affected cognitive performance. High-normal blood glucose levels were associated with decreased delayed associative memory, reduced accuracy of working memory processing among women, and slower working memory processing among men. Elevated pulse pressure was associated with slower perceptual-motor processing. Results suggest that blood glucose levels and pulse pressure may be sensitive indicators of cognitive status in healthy adults; however, longitudinal research is needed to determine whether such relatively mild elevations in this select group predict age-related cognitive declines.

IQ in early adulthood, socioeconomic position, and unintentional injury mortality by middle age: a cohort study of more than 1 million Swedish men

The authors evaluated the little-examined association between intelligence (IQ) and injury mortality and, for the first known time, explored the extent to which IQ might explain established socioeconomic inequalities in injury mortality. A nationwide cohort of 1,116,442 Swedish men who underwent IQ testing at about 18 years of age was followed for mortality experience for an average of 22.6 years. In age-adjusted analyses in which IQ scores were classified into 4 groups, relative to the highest scoring category, the hazard ratio in the lowest was elevated for all injury types: poisonings (hazard ratio (HR) = 5.82, 95% confidence interval (CI): 4.25, 7.97), fire (HR = 4.39, 95% CI: 2.51, 7.77), falls (HR = 3.17, 95% CI: 2.19, 4.59), drowning (HR = 3.16, 95% CI: 1.85, 5.39), and road injury (HR = 2.17, 95% CI: 1.91, 2.47). Dose-response effects across the full IQ range were evident (P-trend < 0.001). Control for potential covariates, including socioeconomic position, had little impact on these gradients. When socioeconomic disadvantage—indexed by parental and subject's own occupational social class—was the exposure of interest, IQ explained a sizable portion (19%–86%) of the relation with injury mortality. These findings suggest that IQ may have an important role both in the etiology of injuries and in explaining socioeconomic inequalities in injury mortality.

Does executive function explain the IQ-mortality association? Evidence from the Canadian study on health and aging

OBJECTIVE

To assess the robustness of the association between intelligence quotient (IQ) and mortality in older adults and to examine whether or not the association can be explained by more specific cognitive processes, including individual differences in executive functioning.

METHODS

We examined the associations among Full Scale IQ, individual IQ subtest scores, and 10-year mortality among older community-dwelling, adult participants in the Canadian Study of Health and Aging, who were verified as disease and cognitive-impairment free at baseline via comprehensive medical and neurological evaluation (n = 516). Survival analysis including Cox proportional hazards regression models were used to examine mortality risk as a function of Full Scale IQ and its specific subcomponents.

RESULTS

An inverse association was found between IQ and mortality, but this did not survive adjustment for demographics and education. The association between IQ and mortality seemed to be predominantly accounted for by performance on one specific IQ subtest that taps executive processes (i.e., Digit Symbol (DS)). Performance on this subtest uniquely and robustly predicted mortality in both unadjusted and adjusted models, such that a 1-standard deviation difference in performance was associated with a 28% change in risk of mortality over the 10-year follow-up interval in adjusted models.

CONCLUSIONS

The association between IQ and mortality in older adults may be predominantly attributable to individual differences in DS performance.

Physical control and coordination in childhood and adult obesity: Longitudinal Birth Cohort Study

OBJECTIVE

To identify whether measures of childhood physical control and coordination as markers of neurological function are associated with obesity in adults.

DESIGN

Longitudinal birth cohort study.

SETTING

National child development study in Great Britain.

PARTICIPANTS

11,042 people born during one week in 1958.

MAIN OUTCOME MEASURE

Obesity at age 33 years defined as body mass index >or=30.

RESULTS

Among 7990 cohort members at age 7 years, teachers reported that poor hand control, poor coordination, and clumsiness "certainly applied" more often among those who would be obese adults, producing adjusted odds ratios of 1.57 (95% confidence interval 1.13 to 2.20; P=0.008) for poor hand control, 2.30 (1.52 to 3.46; P<0.001) for poor coordination, and 3.91 (2.61 to 5.87; P<0.001) for clumsiness. Among 6875 participants who had doctor administered assessments with continuous scores at age 11 years, poorer function was associated with later obesity, indicated by adjusted odds ratios (change in risk per unit increase in score) of 0.88 (0.81 to 0.96; P=0.003) for copying designs, 0.84 (0.78 to 0.91; P<0.001) for marking squares, and 1.14 (1.06 to 1.24; P<0.001) for picking up matches (a higher score indicates poor function in this test). Further adjustment for contemporaneous body mass index at age 7 or 11 years did not eliminate statistical significance for any of the associations.

CONCLUSION

Some aspects of poorer neurological function associated with adult obesity may have their origins in childhood.

IQ in late adolescence/early adulthood, risk factors in middle age and later all-cause mortality in men: the Vietnam Experience Study

OBJECTIVE

To examine the role of potential mediating factors in explaining the IQ-mortality relation.

DESIGN, SETTING AND PARTICIPANTS

A total of 4316 male former Vietnam-era US army personnel with IQ test results at entry into the service in late adolescence/early adulthood in the 1960/1970s (mean age at entry 20.4 years) participated in a telephone survey and medical examination in middle age (mean age 38.3 years) in 1985-6. They were then followed up for mortality experience for 15 years.

MAIN RESULTS

In age-adjusted analyses, higher IQ scores were associated with reduced rates of total mortality (hazard ratio (HR)(per SD increase in IQ) 0.71; 95% CI 0.63 to 0.81). This relation did not appear to be heavily confounded by early socioeconomic position or ethnicity. The impact of adjusting for some potentially mediating risk indices measured in middle age on the IQ-mortality relation (marital status, alcohol consumption, systolic and diastolic blood pressure, pulse rate, blood glucose, body mass index, psychiatric and somatic illness at medical examination) was negligible (<10% attenuation in risk). Controlling for others (cigarette smoking, lung function) had a modest impact (10-17%). Education (0.79; 0.69 to 0.92), occupational prestige (0.77; 0.68 to 0.88) and income (0.86; 0.75 to 0.98) yielded the greatest attenuation in the IQ-mortality gradient (21-52%); after their collective adjustment, the IQ-mortality link was effectively eliminated (0.92; 0.79 to 1.07).

CONCLUSIONS

In this cohort, socioeconomic position in middle age might lie on the pathway linking earlier IQ with later mortality risk but might also partly act as a surrogate for cognitive ability.

The predictive value of different socio-economic indicators for overweight in nine European countries

OBJECTIVES

To assess which socio-economic indicator best predicts overweight in the European Union: educational attainment, occupational class or household income.

SETTING

The prevalence of overweight is strongly related to socio-economic position. The relative importance of different socio-economic dimensions is uncertain, and might vary between countries.

DESIGN AND SUBJECTS

Cross-sectional self-report data of the European Community Household Panel were obtained from nine countries (n 52,855; age 25-64 years). Uni- and multivariate regression analyses were employed to predict overweight (BMI >or= 25 kg/m2) in relationship to socio-economic indicators. Occupational class was measured using the new European Socioeconomic Classification.

RESULTS

Large socio-economic differences in overweight were observed in all countries, especially for women. For both sexes, a low educational attainment was the strongest predictor of overweight. After controlling for education, overweight was negatively related to household income in women, but positively in men. Similar patterns were found for occupational class. For women, but not for men, educational inequalities in overweight were generally greater in Southern European countries. A similar pattern of inequalities in overweight was observed for all ages between 25 and 64 years.

CONCLUSIONS

Across Europe, overweight was more strongly and more consistently related to educational attainment than to occupational class or household income. People with lower educational attainment should be a specific target group for programmes and policies that aim to prevent overweight.

Locus of control at age 10 years and health outcomes and behaviors at age 30 years: the 1970 British Cohort Study

OBJECTIVE

To examine the relationship between locus of control at age 10 years and self-reported health outcomes (overweight, obesity, psychological distress, health, and hypertension) and health behaviors (smoking and physical activity) at age 30, controlling for sex, childhood IQ, educational attainment, earnings, and socioeconomic position.

METHODS

Participants were members of the 1970 British Cohort Study, a national birth cohort. At age 10, 11,563 children took tests to measure locus of control and IQ. At age 30, 7551 men and women (65%) were interviewed about their health and completed a questionnaire about psychiatric morbidity.

RESULTS

Men and women with a more internal locus of control score in childhood had a reduced risk of obesity (odds ratio, 95% CI, for a SD increase in locus of control, 0.86, 0.78-0.95), overweight (0.87, 0.82-0.93), fair or poor self-rated health (0.89, 0.81-0.97), and psychological distress (0.86, 0.76-0.95). Women with a more internal locus of control had a reduced risk of high blood pressure (0.84, 0.76-0.92). Associations between childhood IQ and risk of obesity and overweight were weakened by adjustment for internal locus of control.

CONCLUSION

Having a stronger sense of control over one's own life in childhood seems to be a protective factor for some aspects of health in adult life. Sense of control provides predictive power beyond contemporaneously assessed IQ and may partially mediate the association between higher IQ in childhood and later risk of obesity and overweight.

A life course of adiposity and dementia

Adiposity, commonly measured as body mass index (BMI), may influence or be influenced by brain structures and functions involved in dementia processes. Adipose tissue changes in degree and intensity over the lifespan, and has been shown to influence brain development in relationship to early and late measures of cognitive function, intelligence, and disorders of cognition such as dementia. A lower BMI is associated with prevalent dementia, potentially due to underlying brain pathologies and correspondingly greater rates of BMI or weight decline observed during the years immediately preceding clinical dementia onset. However, high BMI during mid-life or at least approximately 5-10 years preceding clinical dementia onset may increase risk. The interplay of adiposity and the brain occurring over the course of the lifespan will be discussed in relationship to developmental origins, mid-life sequelae, disruptions in brain structure and function, and late-life changes in cognition and dementia. Characterizing the life course of adiposity among those who do and do not become demented enhances understanding of biological underpinnings relevant for understanding the etiologies of both dementia and obesity and their co-existence.

Pre-morbid intelligence, the metabolic syndrome and mortality: the Vietnam Experience Study

AIMS/HYPOTHESIS

We examined the relationship between pre-morbid intelligence quotient (IQ) and the metabolic syndrome, and assessed the role of the metabolic syndrome as a mediating factor in the association of IQ with total and cardiovascular disease (CVD) mortality.

METHODS

In this cohort study, 4,157 men with IQ test results from late adolescence or early adulthood [mean age (range) 20.4 (16-30) years] attended a clinical examination in middle-age [38.3 (31-46) years] at which the components of the metabolic syndrome were measured. They were then followed for 15 years to assess mortality.

RESULTS

In age-adjusted analyses, IQ was significantly inversely related to four of the five individual components comprising the metabolic syndrome: hypertension, high BMI, high triglycerides and high blood glucose, but not low HDL-cholesterol. After controlling for a range of covariates that included socioeconomic position, higher IQ scores were associated with a reduced prevalence of the metabolic syndrome itself (odds ratio(1 SD increase in IQ) 0.87, 95% CI 0.78-0.98). Structural equation modelling revealed that education was not a mediator of the relationship between IQ and the metabolic syndrome. The metabolic syndrome partially mediated the relationship between IQ and CVD but not that between IQ and total mortality.

CONCLUSIONS/INTERPRETATION

In this cohort, higher scores on a pre-morbid IQ test were associated with a lower prevalence of the metabolic syndrome and most of its components. The metabolic syndrome was a mediating variable in the IQ-CVD relationship.

Mental ability across childhood in relation to risk factors for premature mortality in adult life: the 1970 British Cohort Study

OBJECTIVE

To examine the relation of scores on tests of mental ability across childhood with established risk factors for premature mortality at the age of 30 years.

METHODS

A prospective cohort study based on members of the British Cohort Study born in Great Britain in 1970 who had complete data on IQ scores at five (N = 8203) or 10 (N = 8171) years of age and risk factors at age 30 years.

RESULTS

In sex-adjusted analyses, higher IQ score at age 10 years was associated with a reduced prevalence of current smoking (OR(per 1 SD advantage in IQ) 0.84; 95% CI 0.80, 0.88), overweight (0.88; 0.84, 0.92), obesity (0.84; 0.79, 0.92), and hypertension (0.90; 0.83, 0.98), and an increased likelihood of having given up smoking by the age of 30 years (1.25; 1.18, 1.24). These gradients were attenuated after adjustment for markers of socioeconomic circumstances across the life course, particularly education. There was no apparent relationship between IQ and diabetes. Essentially the same pattern of association was evident when the predictive value of IQ scores at five years of age was examined.

CONCLUSIONS

The mental ability-risk factor gradients reported in the present study may offer some insights into the apparent link between low pre-adult mental ability and premature mortality.

Body mass index and neuropsychological function in healthy children and adolescents

Elevated body mass index (BMI) is associated with adverse neurocognitive outcome in adults, including reduced neuropsychological test performance. It is unknown whether this relationship also exists in children and adolescents. A total of 478 children and adolescents (age 6-19) without significant medical or psychiatric history provided demographic information and completed a computerized cognitive test battery. Participants were categorized using clinical criteria into underweight, normal weight, at risk for overweight and overweight groups based on age and gender. Partial correlation and MANCOVA analyses adjusting for age and intellectual function found no relationship between BMI and cognitive test performance in the full sample. However, analyses performed separately by gender showed that underweight females exhibited poorer memory performance than other female BMI groups. These findings suggest that elevated BMI is not associated with cognitive function in healthy children and adolescents, though underweight might be a risk factor for reduced memory performance in females. Further work is needed to clarify the inconsistent findings between adults and minors.

To what extent does IQ 'explain' socio-economic variations in function?

Background

The aims of this study were to examine the extent to which higher intellectual abilities protect higher socio-economic groups from functional decline and to examine whether the contribution of intellectual abilities is independent of childhood deprivation and low birth weight and other socio-economic and developmental factors in early life.

Methods

The Maastricht Aging Study (MAAS) is a prospective cohort study based upon participants in a registration network of general practices in The Netherlands. Information was available on 1211 men and women, 24 – 81 years old, who were without cognitive impairment at baseline (1993 – 1995), who ever had a paid job, and who participated in the six-year follow-up. Main outcomes were longitudinal decline in important components of quality of life and successful aging, i.e., self-reported physical, affective, and cognitive functioning.

Results

Persons with a low occupational level at baseline showed more functional decline than persons with a high occupational level. Socio-economic and developmental factors from early life hardly contributed to the adult socio-economic differences in functional decline. Intellectual abilities, however, took into account more than one third of the association between adult socio-economic status and functional decline. The contribution of the intellectual abilities was independent of the early life factors.

Conclusion

Rather than developmental and socio-economic characteristics of early life, the findings substantiate the importance of intellectual abilities for functional decline and their contribution – as potential, but neglected confounders – to socio-economic differences in functioning, successful aging, and quality of life. The higher intellectual abilities in the higher socio-economic status groups may also underlie the higher prevalences of mastery, self-efficacy and efficient coping styles in these groups.

The association between cognitive ability measured at ages 18-20 and coronary heart disease in middle age among men: a prospective study using the Swedish 1969 conscription cohort

An association between childhood cognitive ability measured with IQ-tests and coronary heart disease (CHD) incidence has been reported recently. It is not clear from those studies to what extent the increased relative risk associated with lower cognitive ability may be explained by CHD risk factors. This study aims to investigate the association between cognitive ability measured at age 18-20 and incidence of CHD, acute myocardial infarction (AMI), and stroke among middle aged men adjusting for risk factors for CHD over the life course. Data on cognitive ability, and other risk factors for CHD (height, parental cardiovascular diseases (CVD) mortality, blood pressure, smoking, risky use of alcohol, BMI), were collected from 49,321 men, born in 1949-51, at conscription for compulsory military training in 1969/70 in Sweden. Information on socioeconomic factors in childhood (socioeconomic position and crowded housing) and adulthood (education, socioeconomic position, and income), as well as information on mortality and morbidity, was collected through national registers. Cognitive ability showed an inverse and graded association with CHD incidence. Adjustment for indicators of poor childhood circumstances, behavioural factors measured in late adolescence, and adult social circumstances strongly attenuated the increased risks of CHD and AMI. The contribution from adult social circumstances, after adjustment from all other factors, was very small. After adjustment for all risk factors no significantly increased relative risk was seen for stroke incidence. After adjustment for risk factors over the life course, the risk of CHD and AMI associated with cognitive ability decreased substantially, and was of borderline significance. Given the results from this study it is unlikely that cognitive ability is a risk factor on its own for CHD, AMI and stroke among men below 54 years of age.

IQ in early adulthood and later cancer risk: cohort study of one million Swedish men

BACKGROUND

While several studies have reported an inverse relation between IQ and total mortality rates, little is known about the association, if any, between IQ and disease-specific outcomes, particularly cancer.

METHODS

A cohort of 959,540 Swedish men who underwent IQ testing at military conscription at around 19 years of age, and who were followed for incident cancer. Hazards ratios for the relation between IQ and 20 cancer outcomes were computed using Cox regression.

RESULTS

During an average of 19.5 years of follow-up, there were 10 273 new cancer cases. IQ showed few associations with the cancer end points studied. There was a suggestion that IQ was positively associated with lung cancer, and inversely related to stomach, oesophageal and liver malignancies, although effects were modest. The only robust gradient was found for IQ in relation to skin cancer (HRper one standard deviation advantage in IQ; 95% confidence interval 1.18; 1.13, 1.24; P value for trend across categories: <0.01), which was attenuated but retained statistical significance after adjustment for indices of socioeconomic position across the life course.

CONCLUSIONS

In this large cohort of Swedish men followed into middle age, IQ was related to very few of the cancer outcomes under investigation. This indicates that the recent observation that low IQ is related to increased mortality rates may not be generated by an IQ-cancer gradient. Given that the present analyses are among the first to examine these associations, replication is required.

Childhood IQ in relation to risk factors for premature mortality in middle-aged persons: the Aberdeen Children of the 1950s study

OBJECTIVE

A series of studies have shown an association between high childhood IQ scores and reduced rates of total mortality in adulthood. Several mechanisms have been advanced to explain these relationships, including mediation via established risk factors. This study examines the association between childhood IQ and a range of established physiological and behavioural risk factors for premature mortality in adulthood.

DESIGN, SETTING AND PARTICIPANTS

In 1962, 12,150 children took part in a school-based survey when their IQ scores were extracted from educational records. When re-surveyed forty years later (n = 7183; 63.7% response), they self-reported information on risk factors for premature mortality (smoking, heavy alcohol consumption, obesity, height, hypertension and diabetes).

MAIN RESULTS

In sex-adjusted analyses based on an analytical sample of 5340 (2687 women), higher childhood IQ scores were associated with a decreased prevalence of ever having smoked regularly in adulthood (OR(per SD increase in IQ) (95% CI): 0.77 (0.73 to 0.81)), heavy alcohol consumption (0.89 (0.84 to 0.94)), obesity (0.78 (0.72 to 0.83)) and overweight (0.86 (0.81 to 0.91)). Higher IQ scores were similarly related to a reduced prevalence of short stature and higher rates of smoking cessation in smokers; effects that were stronger in women (p value for interaction: < or =0.04). Adjusting for indicators of early and, particularly, later-life socioeconomic circumstances led to heavy attenuation of these gradients with statistical significance at conventional levels lost in most analyses.

CONCLUSIONS

The IQ-risk factor gradients reported may offer some insights into the apparent link between high pre-adult IQ and reduced mortality rates.

Premorbid (early life) IQ and later mortality risk: systematic review

PURPOSE

Studies of middle-aged and particularly older-aged adults found that those with higher scores on tests of IQ (cognitive function) had lower rates of later mortality. Interpretation of such findings potentially is hampered by the problem of reverse causality: such somatic diseases as diabetes or hypertension, common in older adults, can decrease cognitive function. Studies that provide extended follow-up of the health experience of individuals who had their (premorbid) IQ assessed in childhood and/or early adulthood minimize this concern. The purpose of the present report is to systematically locate, evaluate, and interpret the findings of all such studies.

METHODS

We systematically identified individual-level studies linking premorbid IQ with later mortality by using four approaches: search of electronic databases (MEDLINE, EMBASE, and PSYCHINFO); scrutiny of the reference sections of identified reports; search of our own files; and contact with researchers in the field. Study quality was assessed by using predefined criteria.

RESULTS

Nine cohort studies met the inclusion criteria. Overall, study quality was moderate. All reports showed an inverse IQ-mortality relation; i.e., higher IQ scores were associated with decreased mortality risk. The nature of this relation (i.e., dose-response or threshold) and whether it differs by sex was unclear. The IQ-mortality association did not appear to be explained by reverse causality or selection bias. Confounding by other early-life factors also did not seem to explain the association, although some studies were not well characterized in this regard. Adult socioeconomic position appeared to mediate the IQ-mortality association in some studies, but this was not a universal finding.

CONCLUSIONS

In all studies, higher IQ in the first two decades of life was related to lower rates of total mortality in middle to late adulthood. Some plausible mechanistic pathways exist, but further examination is required. The precise nature of the IQ-mortality relation (particularly in ethnic minorities and women) and the link between IQ and disease-specific outcomes also warrants further research.

Childhood IQ and life course socioeconomic position in relation to alcohol induced hangovers in adulthood: the Aberdeen children of the 1950s study

OBJECTIVE

To examine the association between scores on IQ tests in childhood and alcohol induced hangovers in middle aged men and women.

DESIGN, SETTING, AND PARTICIPANTS

A cohort of 12 150 people born in Aberdeen (Scotland) who took part in a school based survey in 1962 when IQ test scores were extracted from educational records. Between 2000 and 2003, 7184 (64%) responded to questionnaire inquiries regarding drinking behaviour.

MAIN OUTCOME MEASURES

Self reported hangovers attributable to alcohol consumption on two or more occasions per month.

RESULTS

Higher IQ scores at 11 years of age were associated with a lower prevalence of hangovers in middle age (OR(per one SD advantage in IQ score); 95% CI: 0.80; 0.72, 0.89). This relation was little affected by adjustment for childhood indicators of socioeconomic position (0.82; 0.74, 0.91) but was considerably attenuated after control for adult variables (fully adjusted model: 0.89; 0.79, 1.01).

CONCLUSIONS

Higher childhood IQ was related to a lower prevalence of alcohol induced hangovers in middle aged men and women. The IQ-hangover effect may at least partially explain the link between early life IQ and adult mortality. This being the first study to examine this relation, more evidence is required.

Adiposity indices and dementia

Indicators of adiposity, such as body-mass index (BMI), may be markers for changes in energy metabolism that influence dementia risk, progression, and ultimately death. Cross-sectional studies show that people with dementia have a lower BMI than those without dementia, which is potentially due to a greater rate of BMI decline occurring during the years immediately preceding dementia onset. However, a high BMI can also increase the risk for dementia when measured before clinical dementia onset, which might be due to vascular disorders or bioactive hormonal compounds that are secreted by adipose tissue. In this personal view, I consider how dementia is associated with BMI by looking at the role of BMI and obesity syndromes, mechanisms associated with adiposity, and the potential for hypothalamic dysregulation during the life course. Understanding the life course of adiposity by use of common surrogate measures, such as BMI, among those who do and do not develop dementia is relevant for understanding the causes of dementia and for shaping possible treatment options.