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- Titova, Olga E.
(author)
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Metabolic Health and Cognitive Function : The Roles of Lifestyle and Shift Work
- 2019
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Doctoral thesis (other academic/artistic)abstract
- The risk of cognitive impairment and metabolic disturbances increases during aging. Healthy lifestyle habits, such as a regular intake of fatty fish and adherence to the Mediterranean diet (MeDi), have been shown to slow age-related cognitive decline and decrease the risk of metabolic disturbances. Conversely, poor lifestyle habits including habitual short sleep duration as well as irregular work schedules (e.g. night shift work) have been correlated with lower cognitive performance and increased risk of having metabolic syndrome (MetS). However evidence is not conclusive regarding the above mentioned associations. The aim of this thesis was to investigate associations of diet, sleep, and shift work with metabolic health or cognitive performance in two Swedish cohorts.In Paper I and II we examined whether the dietary intake of omega-3 fatty acids and adherence to MeDi were related to measures of brain health in elderly subjects. To this aim, we used scores from the 7-minute cognitive screening test (7MS) and brain volume determined by magnetic resonance imaging. In Paper I, self-reported dietary intake of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) at age 70 was positively associated with cognitive performance and global gray matter volume at age 75. In Paper II, the fully-adjusted main analysis revealed that the MeDi score was not linked to measures of brain health. However, low intake of the MeDi component meat and meat products was associated with better performance on the 7MS and larger total brain volume.Paper III and IV included subjects aged 45-75 years. In Paper III we demonstrated that current and recent former shift workers (including shifts outside traditional working hours during the past 5 years at the time of the survey) performed worse on the trail making test (TMT) than non-shift workers. The TMT is a test evaluating executive cognitive function, and the performance on this test decreases with age. In Paper IV, sleep duration, sleep disturbances, and sleep-disordered breathing were all linked to an increased prevalence of MetS. Some of the observed associations were age-specific. For example, whereas both short and long sleep durations were linked to a higher prevalence of MetS in younger individuals (<65 years), only long sleep duration did so in the older participants. Collectively, the findings of this thesis suggest that maintaining healthy dietary habits, having high-quality sleep, and following a regular work schedule may be recommended strategies to mitigate age-related morbidities.
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| 2. |
- van Egmond, Lieve T., 1992-
(author)
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The psycho-metabolic consequences of sleep loss in people
- 2023
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Doctoral thesis (other academic/artistic)abstract
- Night work is vital for maintaining our 24/7 society; however, in the long run, it may have adverse health consequences like obesity and Alzheimer’s disease. By performing one of the most extensive experimental in-laboratory studies to date, I sought to investigate how sleep deprivation impacts important features like how a person responds to others and how well a person can sustain attention and wakefulness during simulated night work. To this end, in Paper I, I used eye tracking to show that young adults were less visually attentive to faces after sleep deprivation, irrespective of the displayed emotion. Additionally, participants rated faces as less trustworthy and attractive after the nocturnal vigil. In conclusion, the observed effects suggest that night work may impact emotional regulation. Whether the change in face processing increases the odds of negative affect and social withdrawal remains unclear.Using the same cohort in Paper II, I found that women and people with obesity struggled more with overnight wakefulness (measured by questionnaires, vigilance, and electroencephalography) than men and people with normal weight, respectively. Strikingly, these groups also exhibited increased blood levels of brain health biomarkers following total sleep loss. These results indicate that a person’s biological sex and weight status may moderate to which extent night work adversely affects brain health and occupational performance.Sleep deprivation drives the development of obesity. However, whether similar mechanisms accounting for this weight-promoting effect of sleep loss apply to people who already have obesity is not well researched. Additionally, most experimental studies focused on the effects of acute sleep loss on the energy balance in men. With these gaps in mind, using the above-described cohort, Paper III focused on three prominent endocrine regulators of energy balance, namely leptin, known to promote satiety, and the hunger-promoting hormones ghrelin and adiponectin. Overall, I observed that lower blood leptin concentrations followed one night of total sleep deprivation while those of ghrelin and adiponectin increased. In addition, post-hoc analyses suggested some sex- and weight-specific differences in the hormonal response to sleep loss. For example, leptin dropped to a greater extent in women. These sex- and weight-specific differences must be replicated in larger studies.While acute sleep loss may predispose humans to gain weight, what we eat can influence our sleep. At age 70, 970 participants from the Uppsala Longitudinal Study of Adult Men (ULSAM) filled out a seven-day food diary and questionnaires surveying for possible sleep problems. Thus, in Paper IV, I investigated whether healthy dietary habits were associated with lower odds of suffering from subjective sleep disturbances. Contrary to my hypothesis, neither the Mediterranean diet nor the Healthy Diet Indicator (based on WHO recommendations) was associated with sleep outcomes. Thus, more controlled interventional studies are needed to systematically evaluate how dietary habits may influence sleep in older men.
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