Risk of Sleep Problems in Middle-Aged and Older Adults Experiencing Bodily Pains: Serial Multiple Mediation Estimates of Emotional Distress and Activity Limitations

OBJECTIVES

Pain is increasingly becoming common among middle-aged and older adults. While research on the association between pain characteristics and sleep problems (SP) is limited in low- and middle-income countries, the underlying mechanisms of the association are poorly understood. This study examines the association of bodily pain intensity and pain interference with SP and investigates the mediating role of activity limitation and emotional distress in this association.

METHODS

We analyzed population-based data, including 1,201 individuals aged ≥50 (mean [SD] age 66.14 [11.85] years) from the 2016-2018 AgeHeaPsyWel-HeaSeeB study in Ghana. Multiple OLS regressions and serial multiple mediation modeling using bootstrapping analyses examined direct and indirect effects from pain to SP through activity limitation and emotional distress.

RESULTS

Regressions demonstrated that pain intensity and interference were significantly associated with higher levels of activity limitation, emotional distress, and SP (range: β = 0.049-0.658). Bootstrapping analysis showed that activity limitation and emotional distress serially mediated the relationship between pain intensity and SP (total effect: β = 0.264, Bootstrap 95% confidence interval [CI] = 0.165-0.362; direct effect: (β = 0.107, Bootstrap 95% CI = 0.005-0.210; total indirect effect: β = 0.156, Bootstrap 95% CI = 0.005-0.210) accounting for ∼59%. Activity limitation and emotional distress mediated pain interference and SP association (total effect: β = 0.404, Bootstrap 95% CI = 0.318-0.490; direct effect: β = 0.292, Bootstrap 95% CI = 0.201-0.384; and total indirect effect: β = 0.112, Bootstrap 95% CI = 0.069-0.156) yielding ∼28%.

CONCLUSION

Our data suggest that activity limitation and emotional distress may convey stress-related risks of pain on SP. Future research should evaluate if activity limitation and emotional distress could be effective targets to reduce the effect of pain on sleep in later-life.

PIXE ANALYSIS OF ATMOSPHERIC AEROSOLS IN THE CITY OF BUENOS AIRES

Lead pollution present in atmospheric aerosols in the city of Buenos Aires was measured in 1989, using Heavy Ion PIXE. Since then, environmental conditions have changed significantly. The usage of unleaded gasoline was introduced, and the utilisation of compressed natural gas as car fuel has increased. Recently, a new sampling campaign of atmospheric aerosols has started, partly in collaboration with the Greenpeace Foundation. The present studies reveal that lead pollution in Buenos Aires has significantly decreased since 1989. The concentrations of other elements are determined as well.

Metabolic alterations without metal accumulation in the ovary of adult Bufo arenarum females, observed after long-term exposure to Zn(2+), followed by toxicity to embryos

Long-term exposure of aquatic organisms to metals, even those considered micronutrients, may affect their metabolism and produce sublethal effects. We evaluated the effects of long-term exposure of adult amphibian (Bufo arenarum) females to 4 microg/L of Zn(2+) (ZnSO(4) x H(2)O) in Ringer solution on the concentration of Zn and Fe, the activity of the key enzyme of the pentose phosphate pathway glucose 6-phosphate dehydrogenase, and glutathione content, both in the liver and ovary of these animals. We also performed early embryonic development studies by in vitro insemination from control and treated females. Zn exposure rendered lower Zn concentrations in the ovaries than did exposure of animals to Ringer solution without metal addition (97 +/- 50 versus 149 +/- 46 Zn microg/wet tissue g). Zn and Fe concentration correlation was positive and linear in the ovary, but was negative and nonlinear in the liver of the studied females. The activity of the enzyme glucose 6-phosphate dehydrogenase decreased (0.0599 +/- 0.0109 versus 0.0776 +/- 0.0263 micromol of NADPH/min x mg of proteins) and the endogenous glutathione content increased (0.027 +/- 0.005 versus 0.018 +/- 0.007 mg/10 mg of proteins) in the ovary but remained unaltered in the liver as a consequence of Zn treatment. Our results suggest the existence of different mechanisms of regulation of Zn and Fe concentrations in the ovary and in the liver of adult B. arenarum females. Binding of Zn to low-molecular-weight proteins, as metallothioneins, may occur in the liver, thus protecting this organ from toxic effects. In the ovary high-molecular-weight proteins, like glucose-6-phosphate dehydrogenase, should be able to bind Zn, leading to oxidative stress responsible for the observed increase in endogenous glutathione content. Inhibition of the pentose phosphate pathway in the ovary by Zn can be responsible for the reproductive failure that we detected through embryos survival studies during early life stages: 81.3 +/- 6.3% of embryos from control females survived versus 63.1 +/- 13.8% of embryos from Zn-treated females at the branchial circulation stage of development.