Find below a selection of research results from the projects on data from SNAC-K.
Lifestyle behaviors and longevity
Maintaining a healthy lifestyle and a rich social networkwas positively associated with survival even among people aged 75 years and older. People who reported being physically active lived 2 years longer than those who did not. Nonsmokers who were physically and mentally active and had a good social network (low risk profile) lived about 5 years longer than those who smoked, were inactive, and had a poor social network (high risk profile). These associations were also found in individuals aged 85 years and older and those with chronic diseases (Rizzuto et al, BMJ 2012).
Genetic influences in aging
Recently, researchers have suggested that there is a relationship between telomere length and longevity such that longer telomeres are associated with an increased life span. We have examined the role of a gene (hTERT) that is involved in the modulation of the human telomerase on longevity in 2 cohorts of older adults—Kungsholmen project and SNAC-K. We found an association between the -1327T/C polymorphism of the hTERT gene and survival in women aged 75+. Female T/T carriers lived 2-3 years longer than the C/C carriers. This effect was not present in men or in younger people aged 60–72 years (Kalpouzos G et al., J Gerontol A Biol Sci Med Sci 2014).
Temporal trends in functional dependence and survival
We compared prevalence, incidence, and mortality associated with ADL disability during the 1990s and 2000s. Both prevalence and incidence of disability remained stable during the last decades in this urban Swedish population, with a trend towards a slow decline. Mortality remained steady among disabled persons but decreased among persons without disability, suggesting that increased life expectancy in the last decades may be essentially driven by longer lives of functionally independent people (Angleman et al, J Gerontol A Biol Sci Med Sci 2014).
Cognition and brain aging
Exploring the individual differences in cognitive changes in healthy aging, we found that age differences in cognitive performance at baseline in SNAC-K are most pronounced for processing speed and episodic memory performance. In addition, single genetic polymorphisms can only explain small portions of the individual differences in these cognitive abilities in old age (Laukka et al, Psychol Aging 2013).
Mental disorders in aging
Moderate/severe unipolar depression was associated with poorer performance on several cognitive tasks, whereas mild depression was associated only with poorer performance in processing speed. No association between depression and short-term memory, general knowledge, or spatial ability was observed. Increasing age, use of pharmacological treatments that may affect cognitive performance, and incipient dementia did not exacerbate the depression-related cognitive deficits (Pantzar et al, Psychol Med 2013).
The effect of diabetes on aging
Genetic association studies suggest that variation in the HHEX–IDE gene region may underlie the relationship between diabetes and dementia. In collaboration with the department of Medical Epidemiology and Biostatistics (MEB), KI, we tested this hypothesis in 2 cohorts of elderly people (Kungsholmen Project and SNAC-K) and found that in both cohorts, the AA genotype interacts with diabetes to multiply the risk of dementia and AD among elderly Swedish people (Xu et al, accepted in PLOS Medicine). Vascular burden undermines brain integrity. In our exploration of the factors that contribute to loss of brain integrity in aging, we found that old age, genetic susceptibility (e.g. APOE ε4), and increased burden of vascular risk factors (e.g. hypertension, diabetes) are associated with brain pathology. Specifically, we showed that the aggregation of heavy alcohol consumption, hypertension, diabetes, and current smoking is detrimental to white-matter integrity, and that this effect is more pronounced among APOE ε4 carriers (Wang et al, Neurology 2015).
Secular trends in dementia occurrence from the 1980s through the 2000s
Data from the Kungsholmen Project and the SNAC-K study showed that the prevalence of dementia was stable between 1987−89 and 2001−04 in central Stockholm, Sweden, whereas the survival of patients with dementia increased. These results suggest that incidence of dementia may have decreased over the last 2 decades in this region (Qiu et al, Neurology 2013).
Effect of negative life events on brain volume
Previous research suggested that psychosocial stress exacerbates the risk for dementia, but because of variations in stress measures and study populations, the results of earlier studies have been inconsistent. In collaboration with the department of MEB, KI, we examined the relationship between negative events experienced throughout the entire lifespan and hippocampal and amygdala volumes in older adults. The results suggest that the effect of negative life events on the brain depends on the time when the events occurred, with the strongest effects observed during the critical time periods of early and late life (Gerritsen et al, Psychol Med 2014).
Air pollution and mortality
In the multicenter European Study of Cohorts for Air Pollution Effects (ESCAPE), researchers investigated the association between natural-cause mortality and long-term exposure to several air pollutants. Data from 22 European cohort studies created a total study population of 367,251. The findings support the hypothesis that there is an association between long-term exposure to ambient particulate matter air pollution and mortality, even at concentrations below the existing European Union limit values (Beelen et al., Lancet 2014).