Previous studies have examined associations of cardiometabolic factors with depression and cognition separately.

To determine if depressive symptoms mediate the association between cardiometabolic factors and cognitive decline in two community studies.

Data for the analyses were drawn from the Rotterdam Study, the Netherlands (n = 2940) and the Whitehall II study, UK (n = 4469).

Mediation analyses suggested a direct association between cardiometabolic factors and cognitive decline and an indirect association through depression: poorer cardiometabolic status at time 1 was associated with a higher level of depressive symptoms at time 2 (standardised regression coefficient 0.07 and 0.06, respectively), which, in turn, was associated with greater cognitive decline between time 2 and time 3 (standardised regression coefficient of −0.15 and −0.41, respectively).

Evidence from two independent cohort studies suggest an association between cardiometabolic dysregulation and cognitive decline and that depressive symptoms tend to precede this decline.

None.

The relationship between the duration of depressive symptoms and mortality remains poorly understood.

To examine whether the duration of depressive symptoms is associated with mortality risk.

Data (n = 9560) came from the English Longitudinal Study of Ageing (ELSA). We assessed depressive symptom duration as the sum of examinations with an eight-item Center for Epidemiologic Studies Depression Scale score of ⩾3; we ascertained mortality from linking our data to a national register.

Relative to those participants who never reported symptoms, the age- and gender-adjusted hazard ratios for elevated depressive symptoms over 1, 2, 3 and 4 examinations were 1.41 (95% CI 1.15–1.74), 1.80 (95% CI 1.44–2.26), 1.97 (95% CI 1.57–2.47) and 2.48 (95% CI 1.90–3.23), respectively (P for trend <0.001). This graded association can be explained largely by differences in physical activity, cognitive function, functional impairments and physical illness.

In this cohort of older adults, the duration of depressive symptoms was associated with mortality in a dose–response manner.

The contribution of education and intelligence to resilience against age-related cognitive decline is not clear, particularly in the presence of ‘normal for age’ minor brain abnormalities.

Participants (n = 208, mean age 69.2 years, s.d. = 5.4) in the Whitehall II imaging substudy attended for neuropsychological testing and multisequence 3T brain magnetic resonance imaging. Images were independently rated by three trained clinicians for global and hippocampal atrophy, periventricular and deep white matter changes.

Although none of the participants qualified for a clinical diagnosis of dementia, a screen for cognitive impairment (Montreal Cognitive Assessment (MoCA) <26) was abnormal in 22%. Hippocampal atrophy, in contrast to other brain measures, was associated with a reduced MoCA score even after controlling for age, gender, socioeconomic status, years of education and premorbid IQ. Premorbid IQ and socioeconomic status were associated with resilience in the presence of hippocampal atrophy.

Independent contributions from a priori risk (age, hippocampal atrophy) and resilience (premorbid function, socioeconomic status) combine to predict measured cognitive impairment.

Hypertension is associated with an increased risk of dementia and depression with uncertain longitudinal associations with brain structure.

To examine lifetime blood pressure as a predictor of brain structure in old age.

A total of 190 participants (mean age 69.3 years) from the Whitehall II study were screened for hypertension six times (1985–2013). In 2012–2013, participants had a 3T-magnetic resonance imaging (MRI) brain scan. Data from the MRI were analysed using automated and visual measures of global atrophy, hippocampal atrophy and white matter hyperintensities.

Longitudinally, higher mean arterial pressure predicted increased automated white matter hyperintensities (P<0.002). Cross-sectionally, hypertensive participants had increased automated white matter hyperintensities and visually rated deep white matter hyperintensities. There was no significant association with global or hippocampal atrophy.

Long-term exposure to high blood pressure predicts hyperintensities, particularly in deep white matter. The greatest changes are seen in those with severe forms of hypertension, suggesting a dose–response pattern.

That risk factors measured in middle age may not fully explain future dementia risk implicates exposures acting earlier in life. Height may capture early-life illness, adversity, nutrition and psychosocial stress.

To investigate the little-explored association between height and dementia death.

Individual participant meta-analysis using 18 prospective general population cohort studies with identical methodologies (1994–2008; n = 181 800).

Mean follow-up of 9.8 years gave rise to 426 and 667 dementia deaths in men and women respectively. The mean heights were 174.4cm (s.d. = 7.3) for men and 161.0cm (s.d. = 6.8) for women. In analyses taking into account multiple covariates, increasing height was related to lower rates of death from dementia in a dose–response pattern (P⩽0.01 for trend). There was evidence of a differential effect by gender (P = 0.016 for interaction). Thus, the association observed in men (hazard ratio per s.d. decrease in height 1.24, 95% CI 1.11–1.39) was markedly stronger than that apparent in women (HR = 1.13, 95% CI 1.03–1.24).

Early-life circumstances, indexed by adult height, may influence later dementia risk.

Identifying modifiable risk factors for cognitive decline may inform prevention of dementia.

To examine the combined impact of cigarette smoking and heavy alcohol consumption on cognitive decline from midlife.

Prospective cohort study (Whitehall II cohort) with three clinical examinations in 1997/99, 2002/04 and 2007/09. Participants were 6473 adults (72% men), mean age 55.76 years (s.d. = 6.02) in 1997/99. Four cognitive tests, assessed three times over 10 years, combined into a global z-score (mean 0, s.d. = 1).

Age-related decline in the global cognitive score was faster in individuals who were smoking heavy drinkers than in non-smoking moderate alcohol drinkers (reference group). The interaction term (P = 0.04) suggested that the combined effects of smoking and alcohol consumption were greater than their individual effects. Adjusting for age, gender, education and chronic diseases, 10-year decline in global cognition was −0.42 z-scores (95% Cl −0.45 to −0.39) for the reference group. In individuals who were heavy alcohol drinkers who also smoked the decline was −0.57 z-scores (95% Cl −0.67 to −0.48); 36% faster than the reference group.

Individuals who were smokers who drank alcohol heavily had a 36% faster cognitive decline, equivalent to an age-effect of 2 extra years over 10-year follow-up, compared with individuals who were non-smoking moderate drinkers.

Life-course socioeconomic factors may have a role in dementia aetiology but there is a current paucity of studies. Meta-analyses of individual participant data would considerably strengthen this evidence base.

To examine the association between socioeconomic status in early life and adulthood with later dementia death.

Individual participant meta-analysis of 11 prospective cohort studies (1994–2004, n = 86508).

Leaving full-time education at an earlier age was associated with an increased risk of dementia death in women (fully adjusted hazard ratio (HR) for age ⩽14 v. age ⩾16: HR = 1.76, 95% Cl 1.23–2.53) but not men. Occupational social class was not statistically significantly associated with dementia death in men or women.

Lower educational attainment in women was associated with an increased risk of dementia-related death independently of common risk behaviours and comorbidities.

Inequality in health and treatment of disease across socioeconomic status groups is a major public health issue.

To examine differences in socioeconomic status in common mental disorders and use of psychotherapy provided by the public and private sector in the UK between 1991 and 2009.

During these years, 28 054 men and women responded to annual surveys by the nationally representative, population-based British Household Panel Survey (on average 7 measurements per participant; 207 545 person-observations). In each year, common mental disorders were assessed with the self-reported 12-item General Health Questionnaire and socioeconomic status was assessed on the basis of household income, occupational status and education.

Higher socioeconomic status was associated with lower odds of common mental disorder (highest v. lowest household income quintile odds ratio (OR) 0.88, 95% CI 0.82–0.94) and of being treated by publicly provided psychotherapy (OR = 0.43, 95% CI 0.34–0.55), but higher odds of being a client of private psychotherapy (OR = 3.33, 95% CI 2.36–4.71). The status difference in publicly provided psychotherapy treatment was more pronounced at the end of follow-up (OR = 0.36, 95% CI 0.23–0.56, in 2005–2009) than at the beginning of the follow-up period (OR =0.96, 95% CI 0.66–1.39, in 1991–1994; time interaction P<0.001). The findings for occupational status and education were similar to those for household income.

The use of publicly provided psychotherapy has improved between 1991 and 2009 among those with low socioeconomic status, although social inequalities in common mental disorders remain.

Patient overcrowding and violent assaults by patients are two major problems in psychiatric healthcare. However, evidence of an association between overcrowding and aggressive behaviour among patients is mixed and limited to small-scale studies.

This study examined the association between ward overcrowding and violent physical assaults in acute-care psychiatric in-patient hospital wards.

Longitudinal study using ward-level monthly records of bed occupancy and staff reports of the timing of violent acts during a 5-month period in 90 in-patient wards in 13 acute psychiatric hospitals in Finland. In total 1098 employees (physicians, ward head nurses, registered nurses, licensed practical nurses) participated in the study. The outcome measure was staff reports of the timing of physical assaults on both themselves and ward property.

We found that 46% of hospital staff were working in overcrowded wards, as indicated by >10 percentage units of excess bed occupancy, whereas only 30% of hospital personnel were working in a ward with no excess occupancy. An excess bed occupancy rate of >10 percentage units at the time of an event was associated with violent assaults towards employees (odds ratio (OR) = 1.72, 95% CI 1.05–2.80; OR = 3.04, 95% CI 1.51–6.13 in adult wards) after adjustment for confounding factors. No association was found with assaults on ward property (OR = 1.06, 95% CI 0.75–1.50).

These findings suggest that patient overcrowding is highly prevalent in psychiatric hospitals and, importantly, may increase the risk of violence directed at staff.

Studies of diet and depression have focused primarily on individual nutrients.

To examine the association between dietary patterns and depression using an overall diet approach.

Analyses were carried on data from 3486 participants (26.2% women, mean age 55.6 years) from the Whitehall II prospective cohort, in which two dietary patterns were identified: ‘whole food’ (heavily loaded by vegetables, fruits and fish) and ‘processed food’ (heavily loaded by sweetened desserts, fried food, processed meat, refined grains and high-fat dairy products). Self-reported depression was assessed 5 years later using the Center for Epidemiologic Studies – Depression (CES–D) scale.

After adjusting for potential confounders, participants in the highest tertile of the whole food pattern had lower odds of CES–D depression (OR = 0.74, 95% CI 0.56–0.99) than those in the lowest tertile. In contrast, high consumption of processed food was associated with an increased odds of CES–D depression (OR = 1.58, 95% CI 1.11–2.23).

In middle-aged participants, a processed food dietary pattern is a risk factor for CES–D depression 5 years later, whereas a whole food pattern is protective.

Prospective data on the association between common mental disorders and obesity are scarce, and the impact of ageing on this association is poorly understood.

To examine the association between common mental disorders and obesity (body mass index 30 kg/m2) across the adult life course.

The participants, 6820 men and 3346 women, aged 35–55 were screened four times during a 19-year follow-up (the Whitehall II study). Each screening included measurements of mental disorders (the General Health Questionnaire), weight and height.

The excess risk of obesity in the presence of mental disorders increased with age (P = 0.004). The estimated proportion of people who were obese was 5.7% at age 40 both in the presence and absence of mental disorders, but the corresponding figures were 34.6% and 27.1% at age 70. The excess risk did not vary by gender or according to ethnic group or socioeconomic position.

The association between common mental disorders and obesity becomes stronger at older ages.