Environmental risk factors for dementia are poorly understood. Aluminium and fluorine in drinking water have been linked with dementia but uncertainties remain about this relationship.

In the largest longitudinal study in this context, we set out to explore the individual effect of aluminium and fluoride in drinking water on dementia risk and, as fluorine can increase absorption of aluminium, we also examine any synergistic influence on dementia.

We used Cox models to investigate the association between mean aluminium and fluoride levels in drinking water at their residential location (collected 2005–2012 by the Drinking Water Quality Regulator for Scotland) with dementia in members of the Scottish Mental Survey 1932 cohort who were alive in 2005.

A total of 1972 out of 6990 individuals developed dementia by the linkage date in 2012. Dementia risk was raised with increasing mean aluminium levels in women (hazard ratio per s.d. increase 1.09, 95% CI 1.03–1.15, P < 0.001) and men (1.12, 95% CI 1.03–1.21, P = 0.004). A dose-response pattern of association was observed between mean fluoride levels and dementia in women (1.34, 95% CI 1.28–1.41, P < 0.001) and men (1.30, 95% CI 1.22–1.39, P < 0.001), with dementia risk more than doubled in the highest quartile compared with the lowest. There was no statistical interaction between aluminium and fluoride levels in relation with dementia.

Higher levels of aluminium and fluoride were related to dementia risk in a population of men and women who consumed relatively low drinking-water levels of both.

People with dementia are extremely vulnerable in hospital and unscheduled admissions should be avoided if possible.

To identify any predictors of general hospital admission in people with dementia in a well-characterised national prospective cohort study.

A cohort of 730 persons with dementia was drawn from the Scottish Dementia Research Interest Register (47.8% female; mean age 76.3 years, s.d. = 8.2, range 50–94), with a mean follow-up period of 1.2 years.

In the age- and gender-adjusted multivariable model (n = 681; 251 admitted), Neuropsychiatric Inventory score (hazard ratio per s.d. disadvantage 1.21, 95% CI 1.08–1.36) was identified as an independent predictor of admission to hospital.

Neuropsychiatric symptoms in dementia, measured using the Neuropsychiatric Inventory, predict non-psychiatric hospital admission of people with dementia. Further studies are merited to test whether interventions to reduce such symptoms might reduce unscheduled admissions to acute hospitals.

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.

There are several scales used to detect apathy in disease populations. Since apathy is a prevalent symptom in many neurodegenerative diseases, this is an especially important context in which to identify and compare scales.

To provide an overview of apathy scales validated in generic and specific neurodegenerative disease populations, compare validation studies’ methodological quality and the psychometric properties of the validated apathy scales.

A systematic review of literature was conducted of articles published between 1980 and 2013. The final articles selected for review were rated on methodological quality and the psychometric properties of the scales used were interpreted.

Sixteen articles validating apathy scales were included in the review, five in a generic neurodegenerative sample and eleven in specific neurodegenerative samples. The methodological quality of specific studies varied from poor to excellent. The highest quality, which had psychometrically favorable scales, were the dementia apathy interview and rating (DAIR) and the apathy evaluation scale-clinical version (AES-C) in Alzheimer's disease and the Lille apathy rating scale (LARS) in Parkinson's disease. Generic neurodegenerative disease validation studies were of average methodological quality and yielded inconsistent psychometric properties.

Several instruments can be recommended for use in some specific neurodegenerative diseases. Other instruments should either be validated or developed to assess apathy in more generic populations.

We examined the associations between serum cholesterol measures, statin use, and cognitive function measured in childhood and in old age. The possibility that lifelong (trait) cognitive ability accounts for any cross-sectional associations between cholesterol and cognitive performance in older age, seen in observational studies, has not been tested to date.

Participants were 1,043 men and women from the Lothian Birth Cohort 1936 Study, most of whom had participated in a nationwide IQ-type test in childhood (Scottish Mental Survey of 1947), and were followed up at about age 70 years. Serum cholesterol measures included total cholesterol (TC), high-density lipoprotein cholesterol (HDL-C), triglycerides, and cholesterol:HDL cholesterol ratio. Cognitive outcome measures were age 70 IQ (using the same test as at age 11 years), general cognitive ability (g), processing speed, memory, and verbal ability.

Higher TC, higher HDL-C, and lower triglycerides were associated with higher age 70 cognitive scores in most cognitive domains. These relationships were no longer significant after covarying for childhood IQ, with the exception a markedly attenuated association between TC and processing speed, and triglycerides and age 70 IQ. In the fully adjusted model, all conventionally significant (p < 0.05) effects were removed. Childhood IQ predicted statin use in old age. Statin users had lower g, processing speed, and verbal ability scores at age 70 years after covarying for childhood IQ, but significance was lost after adjusting for TC levels.

These results suggest that serum cholesterol and cognitive function are associated in older age via the lifelong stable trait of intelligence. Potential mechanisms, including lifestyle factors, are discussed.

Reports of attitudes to aging from older people themselves are scarce. Which life course factors predict differences in these attitudes is unknown.

We investigated life course influences on attitudes to aging in healthy, community-dwelling people in the UK. Participants in the Lothian Birth Cohort 1936 completed a self-report questionnaire (Attitudes to Aging Questionnaire, AAQ) at around age 75 (n = 792, 51.4% male). Demographic, social, physical, cognitive, and personality/mood predictors were assessed, around age 70. Cognitive ability data were available at age 11.

Generally positive attitudes were reported in all three domains: low Psychosocial Loss, high Physical Change, and high Psychological Growth. Hierarchical multiple regression found that demographic, cognitive, and physical variables each explained a relatively small proportion of the variance in attitudes to aging, with the addition of personality/mood variables contributing most significantly. Predictors of attitudes to Psychosocial Loss were high neuroticism; low extraversion, openness, agreeableness, and conscientiousness; high anxiety and depression; and more physical disability. Predictors of attitudes to Physical Change were: high extraversion, openness, agreeableness, and conscientiousness; female sex; social class; and less physical disability. Personality predictors of attitudes to Psychological Growth were similar. In contrast, less affluent environment, living alone, lower vocabulary scores, and slower walking speed predicted more positive attitudes in this domain.

Older people's attitudes to aging are generally positive. The main predictors of attitude are personality traits. Influencing social circumstances, physical well-being, or mood may result in more positive attitudes. Alternatively, interventions to influence attitudes may have a positive impact on associated physical and affective changes.

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.

Evidence from observational studies to date suggests that healthy dietary patterns are associated with better cognitive performance in later life. We examined the extent to which childhood intelligence quotient (IQ) and socioeconomic status account for this association.

Analyses were carried out on 882 participants in the Lothian Birth Cohort 1936 Study. Four dietary patterns were extracted using principal components analysis of a food frequency questionnaire, namely “Mediterranean-style,” “health aware,” “traditional,” and “sweet foods.” Cognitive function was assessed at the age of 70 years, including general (g) cognitive ability, processing speed, memory, and verbal ability.

Before adjustment for childhood IQ and socioeconomic status, the “Mediterranean-style” dietary pattern was associated with significantly better cognitive performance (effect size as partial eta-square (ηp2) range = 0.005 to 0.055), and the “traditional” dietary pattern was associated with poorer performance on all cognitive domains measured in old age (ηp2 = 0.009 to 0.103). After adjustment for childhood IQ (measured at the age of 11 years) and socioeconomic status, statistical significance was lost for most associations, with the exception of verbal ability and the “Mediterranean-style” pattern (National Adult Reading Test (NART) ηp2 = 0.006 and Wechsler Test of Adult Reading (WTAR) ηp2 = 0.013), and the “traditional” pattern (NART ηp2 = 0.035 and WTAR ηp2 = 0.027).

Our results suggest a pattern of reverse causation or confounding; a higher childhood cognitive ability (and adult socioeconomic status) predicts adherence to a “healthy” diet and better cognitive performance in old age. Our models show no direct link between diet and cognitive performance in old age; instead they are related via the lifelong-stable trait of intelligence.

We related geographical variation of ‘probable’ presenile Alzheimer's disease (AD PSD) to exposures to possible risk factors for AD PSD and vascular dementia (VaD) and to geographical differences in survival times after presentation with AD PSD.

We found that an ecological measure of socio-economic deprivation was related to VaD but not to AD PSD. Among men with AD PSD and VaD, specific occupations conveyed no altered risk but having fathers who were coal miners was associated with AD PSD and VaD in offspring. Increased paternal age was associated with AD PSD but only in men. These factors acted independently of one another and did not distinguish between geographical areas of high and low incidence.

The length of survival after presentation with AD PSD distinguished between these areas, and when migration between these areas was taken into account, a plausible multifactorial model of the harmful effects of environment emerged, which acted independently of risk factors acting earlier in life.