Cognitive impairment and sleep problems are among the most common health issues in older people. The extent to which they affect life expectancy has not yet been fully established. Research is also investigating whether and how air pollutants, noise and extreme temperatures can damage the brain. An urban lifestyle – including a lack of physical activity, stress, social isolation or environmental pollution – may also play a role. The German National Cohort (NAKO) helps to better understand these links and to find ways to detect dementia earlier and prevent it more effectively.
Germany is undergoing demographic change. The proportion of people aged over 60 is rising steadily, as is the incidence of dementia syndromes. What is the state of mental health in Germany? At the International NAKO Conference in Munich, a keynote presentation and six poster presentations addressed the question of how internal and external factors influence mental health. Cognitive decline in old age is considered a relevant marker of dementia.
Interactions between sleep and cognition
Restful sleep is of fundamental importance for brain health. Epidemiological studies show that almost half of older people are affected by sleep disorders. Cognitive impairments, ranging from mild deficits to dementia, are also widespread in old age. Sleep disorders can accelerate cognitive decline and have a negative impact on survival.
Despite extensive research, there are still gaps in our understanding: sleep and cognitive performance have mostly been studied in isolation, and much of the evidence comes from non-European populations. Furthermore, only a few studies have examined how sleep and cognition change over time as people age. Sociodemographic factors and comorbidities have often been given insufficient consideration.
Jayanta K. Bora and his team from the Centre for Neurodegenerative Diseases (DZNE) in Bonn and the Institute of Sociology and Demography at the University of Rostock investigated the interactions between cognitive function and sleep patterns in older people in Germany (aged 60–74) in a prospective NAKO analysis. Hypothesis: Cognition and sleep patterns influence all-cause mortality in older adults both independently and in combination. Jayanta K. Bora presented the findings in his lecture entitled ‘The Interplay Between Cognitive Function and Sleep Patterns in Relation to Mortality Among Older Adults in Germany: Evidence from NAKO Data’.
Independent, concurrently occurring risk markers
54,998 of the 205,415 NAKO participants from 2014 to 2019 were included in the analysis. Data were available for these participants from interviews, questionnaires, physical examinations and biological samples. Cognitive function was assessed using two tests measuring verbal memory and the ability to control thought and action (executive function); sleep behaviour was assessed across nine domains. The researchers took into account socio-demographic characteristics, as well as information on lifestyle and health status, as further influencing factors. In their model analyses, they investigated the association between cognitive function and sleep patterns and mortality – both separately and in combination.
The ten-year survival rate among people with poor executive function was similarly low to that of people with sleep problems: it stood at 96 per cent for those without severe impairment and at 88 per cent for those with severe impairment. When other influencing factors were taken into account, the risk of death was roughly twice as high for those with severe difficulties in these cognitive abilities and for those with sleep problems that interfere with daily life during the day.
The risk of death was particularly strongly linked to having several co-existing conditions. Snoring and breathing pauses during sleep, by contrast, played hardly any role. Both short sleep duration (less than seven hours) and long sleep duration (more than nine hours) were associated with a higher risk of death. A lower risk was observed in women and in people who were physically fit and of normal weight. A higher risk was associated with being underweight, smoking, unemployment and the loss of a partner.
The authors conclude: “According to the current study, in people aged between 60 and 74, both declining cognitive function and sleep problems were each independently associated with life expectancy. Neither factor, on its own, had any effect on the association between the other. Therefore, both factors – cognitive impairment and sleep disorders – should be considered independently of one another.“
Identifying factors contributing to cognitive decline
Another study involving 70,000 NAKO participants (aged 19–74, 2014–2019, with follow-ups in 2020 and 2022; Wang Y. et al.) investigated the effects of the environment on mental health. The results identified nitrogen dioxide (NO₂), air temperature, the number of hot days and population density as risk factors. Relative humidity, ‘greenness’ and precipitation were found to be protective factors.
The interactions between the environment, urbanisation and neurocognitive functions were the subject of a study involving 25,677 NAKO participants (Ogurtsova K. et al.). Prolonged exposure to fine particulate matter in the air and traffic noise was associated with poorer cognitive function. The degree of urbanisation also played a key role: although environmental pollution was significantly lower in rural areas, poorer cognitive function was observed there than in cities.
How do air temperatures affect cognitive function? A NAKO study (186,250 participants; Nikolaou N. et al.) found that falling temperatures are negatively associated with cognitive function. This applies in particular to younger (<45 years) and older participants (>65 years), as well as residents of urban areas.
Another NAKO study analysed the effects of air pollutants on cognition (115,920 NAKO participants, aged 45–74; Li Q. et al.). Long-term exposure to fine particulate matter (PM2.5, PM10) was associated with impairments in memory and executive function. This suggests that air quality management contributes to the cognitive health of the population, particularly amongst older people.
Autor: Eberhard J. Wormer
Event: International NAKO Conference 2026
Website: www.nako.de/conference
Scientific Board: Dr. Marie-Theres Huemer, Prof. Dr. Wolfgang Lieb, Prof. Dr. Annette Peters, Prof. Dr. Tobias Pischon, Prof. Dr. Tamara Schikowski
Date: 03.09.2026–04.09.2026
Location: Kongresszentrum Helmholtz Munich, Ingolstädter Landstr. 1, D-85764 Neuherberg
Host: Helmholtz Munich
Organization: NAKO e.V.
Contact: conference@nako.de