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Depression severely affects people's health and well-being. Oral diseases have been suggested to be associated with depression, but so far, there is no causal evidence. This study aimed to identify the causal effect of tooth loss on depression among US adults in a natural experiment study.
Instrumental variable analysis was conducted using data from 169 061 respondents born in 1940–1978 who participated in the 2006, 2008 or 2010 waves of the Behavioral Risk Factor Surveillance System (BRFSS). Random variation in tooth loss due to differential childhood exposure to drinking water fluoride was exploited as an instrument.
US adults who were exposed to drinking water fluoride in childhood had more remaining teeth, therefore providing a robust instrument (F = 73.4). For each additional tooth loss, depressive symptoms according to the eight-item Patient Health Questionnaire depression (PHQ-8) score increased by 0.146 (95% CI 0.008–0.284), and the probability of having clinical depression (PHQ ⩾10) increased by 0.81 percentage points (95% CI −0.12 to 1.73).
Tooth loss causally increased depression among US adults. Losing ten or more teeth had an impact comparable to adults with major depressive disorder not receiving antidepressant drugs.
Inadequate iodine intake during pregnancy increases the risk of neonatal morbidity and mortality. We aimed to evaluate whether prenatal supplements containing iodine affect urinary iodine concentrations (UIC) of pregnant women in Malawi.
A randomised controlled trial. Pregnant women (n 1391) were assigned to consume 60 mg/d Fe and 400 µg/d folic acid (IFA) or 18 vitamins and minerals including 250 µg/d iodine (MMN) or 20 g/d small-quantity lipid-based nutrient supplements (SQ-LNS) with similar nutrient contents as MMN group, plus macronutrients (LNS) until childbirth. In a sub-study (n 317), we evaluated group geometric mean urinary iodine concentration (UIC) (µg/L) at 36 weeks of gestation controlling for baseline UIC and compared median (baseline) and geometric mean (36 weeks) UIC with WHO cut-offs: UIC < 150, 150–249, 250–499 and ≥500 reflecting insufficient, adequate, above requirements and excessive iodine intakes, respectively.
Mangochi District, Malawi.
Women ≤20 weeks pregnant.
Groups had comparable background characteristics. At baseline, overall median (Q1, Q3) UIC (319 (167, 559)) suggested iodine intakes above requirements. At 36 weeks, the geometric mean (95 % CI) UIC of the IFA (197 (171, 226)), MMN (212 (185, 243)) and LNS (220 (192, 253)) groups did not differ (P = 0·53) and reflected adequate intakes.
In this setting, provision of supplements containing iodine at the recommended dose to pregnant women with relatively high iodine intakes at baseline, presumably from iodised salt, has no impact on the women’s UIC. Regular monitoring of the iodine status of pregnant women in such settings is advisable. Clinicaltrials.gov identifier: NCT01239693.
Depression is reported to be associated with increased mortality, but underlying mechanisms are uncertain. Associations between anxiety and mortality are also uncertain. In a large population study, we investigated associations between anxiety, depression and mortality over a 3-6 year period. We utilized a unique link between a large regional community survey and a comprehensive national mortality database.
Baseline information on mental and physical health was collected in a population-based health study (n=61,349) (the HUNT-2 study) of adults aged 20 years and over. Anxiety and depressive symptoms were ascertained using the Hospital Anxiety and Depression Scale (HADS). Records were linked with the Norwegian national mortality database.
Case-level depression was a risk-factor for mortality, but case-level anxiety was not (having adjusted for confounding factors). The association between anxiety symptoms and mortality was U-shaped, and anxiety comorbid with depression was associated with lower mortality compared to depression alone. Associations between depression and mortality were partly but not entirely explained by somatic symptoms and conditions, and also physical impairment, but not by smoking, obesity, cholesterol level or blood pressure.
Depression predicted general mortality after adjustment for multiple potential confounding factors. Associations between anxiety symptoms and mortality were U-shaped. Lower mortality was found in comorbid anxiety and depression than in depression alone.
Depression is reported to increase general mortality. For cause-specific mortality, there is evidence for the effect of depression on cardiac mortality and suicide. Less is known as to other mortality diagnoses. The literature on anxiety in relation to mortality is scarce and conflicting. This study investigates empirically the association between anxiety/depression and cause-specific mortality with particular attention to underlying mechanisms and causes of death.
Employing a historical cohort design we utilized a unique link between a large epidemiological cohort study and a comprehensive national mortality database. Baseline information on physical and mental health (HADS) was gathered from the population based health study (N=61349). Causes of death were registered with ICD-10 diagnoses during 4.4 year follow-up.
Case-level depression increased mortality for all major disease-related causes of death, whereas case-level anxiety and comorbid anxiety/depression did not. The effect of depression was equal in cardiac mortality compared to all other causes combined, and confounding factors were also markedly similar. Accidents and suicide was predicted by comorbid anxiety depression.
Depression is a risk factor for all major disease-related causes of death, and is not limited to cardiac mortality or suicide. Case-level anxiety imposes no increased disease-related mortality, but comorbid anxiety depression predicts external causes of death. As the association between depression and cardiac mortality was comparable to the other causes of death combined, and confounding and mediating factors are markedly similar, future investigation as to mechanisms underlying the effect of depression on mortality should not be limited to CVD mortality.
Although much research has focused on socio-demographic determinants of uptake of contraception, few have studied the impact of poor mental health on women's reproductive behaviours. The aim of this study was to examine the impact of poor mental health on women's unmet need for contraception and fertility rate in a low-income country setting.
A population-based cohort of 1026 women recruited in their third trimester of pregnancy in the Butajira district in rural Ethiopia was assessed for symptoms of antenatal common mental disorders (CMDs; depression and anxiety) using Self-Reporting Questionnaire-20. Women were followed up regularly until 6.5 years postnatal (between 2005 and 2012). We calculated unmet need for contraception at 1 year (n = 999), 2.5 (n = 971) and 3.5 years (n = 951) post-delivery of index child and number of pregnancies during study period. We tested the association between CMD symptoms, unmet need for contraception and fertility rate.
Less than one-third of women reported current use of contraception at each time point. Unmet need for birth spacing was higher at 1 year postnatal, with over half of women (53.8%) not using contraception wanting to wait 2 or more years before becoming pregnant. Higher CMD symptoms 1 year post-index pregnancy were associated with unmet need for contraception at 2.5 years postnatal in the unadjusted [odds ratio (OR) 1.09; 95% confidence interval (CI) 1.04–1.15] and fully adjusted model [OR 1.06; 95% CI 1.01–1.12]. During the 6.5 year cohort follow-up period, the mean number of pregnancies per woman was 2.4 (s.d. 0.98). There was no prospective association between maternal CMD and number of pregnancies in the follow-up period.
CMD symptoms are associated with increased unmet need for family planning in this cohort of women with high fertility and low contraceptive use in rural Ethiopia. There is a lack of models of care promoting integration of mental and physical health in the family planning setting and further research is necessary to study the burden of preconception mental health conditions and how these can be best addressed.
Evidence on whether nutritional supplementation affects physical activity (PA) during early childhood is limited. We examined the long-term effects of lipid-based nutrient supplements (LNS) on total PA, moderate-to-vigorous PA (MVPA) and sedentary behaviour (SB) of children at 4–6 years using an accelerometer for 1 week. Their mothers were enrolled in the International Lipid-based Nutrient Supplement-DYAD randomised controlled trial in Ghana, assigned to daily LNS or multiple micronutrients (MMN) during pregnancy through 6 months postpartum or Fe and folic acid (IFA) during pregnancy and placebo for 6 months postpartum. From 6 to 18 months, children in the LNS group received LNS; the other two groups received no supplements. Analysis was done with intention to treat comparing two groups: LNS v. non-LNS (MMN+ IFA). Of the sub-sample of 375 children fitted with accelerometers, 353 provided sufficient data. Median vector magnitude (VM) count was 1374 (interquartile range (IQR) 309), and percentages of time in MVPA and SB were 4·8 (IQR 2) and 31 (IQR 8) %, respectively. The LNS group (n 129) had lower VM (difference in mean −73 (95 % CI −20, −126), P = 0·007) and spent more time in SB (LNS v. non-LNS: 32·3 v. 30·5 %, P = 0·020) than the non-LNS group (n 224) but did not differ in MVPA (4·4 v. 4·7 %, P = 0·198). Contrary to expectations, provision of LNS in early life slightly reduced the total PA and increased the time in SB but did not affect time in MVPA. Given reduced social-emotional difficulties in the LNS group previously reported, including hyperactivity, one possible explanation is less restless movement in the LNS group.
There is limited evidence of the safety and impact of task-shared care for people with severe mental illnesses (SMI; psychotic disorders and bipolar disorder) in low-income countries. The aim of this study was to evaluate the safety and impact of a district-level plan for task-shared mental health care on 6 and 12-month clinical and social outcomes of people with SMI in rural southern Ethiopia.
In the Programme for Improving Mental health carE, we conducted an intervention cohort study. Trained primary healthcare (PHC) workers assessed community referrals, diagnosed SMI and initiated treatment, with independent research diagnostic assessments by psychiatric nurses. Primary outcomes were symptom severity and disability. Secondary outcomes included discrimination and restraint.
Almost all (94.5%) PHC worker diagnoses of SMI were verified by psychiatric nurses. All prescribing was within recommended dose limits. A total of 245 (81.7%) people with SMI were re-assessed at 12 months. Minimally adequate treatment was received by 29.8%. All clinical and social outcomes improved significantly. The impact on disability (standardised mean difference 0.50; 95% confidence interval (CI) 0.35–0.65) was greater than impact on symptom severity (standardised mean difference 0.28; 95% CI 0.13–0.44). Being restrained in the previous 12 months reduced from 25.3 to 10.6%, and discrimination scores reduced significantly.
An integrated district level mental health care plan employing task-sharing safely addressed the large treatment gap for people with SMI in a rural, low-income country setting. Randomised controlled trials of differing models of task-shared care for people with SMI are warranted.
We aimed to identify factors (child diet, physical activity; maternal BMI) associated with body composition of Ghanaian pre-school children.
Longitudinal analysis of the International Lipid-Based Nutrient Supplements (iLiNS)-DYAD-Ghana randomized trial, which enrolled 1320 pregnant women at ≤20 weeks’ gestation and followed them and their infants until 6 and 18 months postpartum, respectively. At follow-up, child age 4–6 years, we collected data on body composition (by 2H dilution), physical activity and diet, extracted dietary patterns using factor analysis, and examined the association of children’s percentage body fat with maternal and child factors by regression analysis.
Eastern Region, Ghana.
Children 4–6 years of age.
The analysis included 889 children with percentage body fat and dietary data at follow-up. We identified two major dietary patterns, a snacking and a cooked foods pattern. Percentage body fat was positively associated (standardized β (se)) with maternal BMI at follow-up (0·10 (0·03); P = 0·003) and negatively associated with physical activity (−0·15 (0·05); P = 0·003, unadjusted for child gender), but not associated with the snacking (0·06 (0·03); P = 0·103) or cooked foods (−0·05 (0·07); P = 0·474) pattern. Boys were more active than girls (1470 v. 1314 mean vector magnitude counts/min; P < 0·0001) and had lower percentage body fat (13·8 v. 16·9 %; P < 0·0001).
In this population, maternal overweight and child physical activity, especially among girls, may be key factors for addressing child overweight/obesity. We did not demonstrate a relationship between the dietary patterns and body fatness, which may be related to limitations of the dietary data available.
Dietary diversity, and in particular consumption of nutrient-rich foods including fruits, vegetables, nuts, beans and animal-source foods, is linked to greater nutrient adequacy. We developed a ‘dietary gap assessment’ to evaluate the degree to which a nation’s food supply could support healthy diets at the population level.
In the absence of global food-based dietary guidelines, we selected the Dietary Approaches to Stop Hypertension (DASH) diet as an example because there is evidence it prevents diet-related chronic disease and supports adequate micronutrient intakes. We used the DASH guidelines to shape a hypothetical ‘healthy’ diet for the test country of Cameroon. Food availability was estimated using FAO Food Balance Sheet data on country-level food supply. For each of the seven food groups in the ‘healthy’ diet, we calculated the difference between the estimated national supply (in kcal, edible portion only) and the target amounts.
In Cameroon, dairy and other animal-source foods were not adequately available to meet healthy diet recommendations: the deficit was −365 kcal (–1527 kJ)/capita per d for dairy products and −185 kcal (–774 kJ)/capita per d for meat, poultry, fish and eggs. Adequacy of fruits and vegetables depended on food group categorization. When tubers and plantains were categorized as vegetables and fruits, respectively, supply nearly met recommendations. Categorizing tubers and plantains as starchy staples resulted in pronounced supply shortfalls: −109 kcal (–457 kJ)/capita per d for fruits and −94 kcal (–393 kJ)/capita per d for vegetables.
The dietary gap assessment illustrates an approach for better understanding how food supply patterns need to change to achieve healthier dietary patterns.
In a perinatal cohort of women in urban and rural Turkey, we investigated associations between antenatal depressive symptoms and subsequent changes in perceived quality of key family relationships.
Of 730 women recruited in their third trimester (94.6% participation), 578 (79.2%) were reassessed at a mean of 4.1 (s.d. = 3.3) months after childbirth, 488 (66.8%) were reassessed at 13.7 (s.d. = 2.9) months, and 448 (61.4%) at 20.8 (s.d. = 2.7) months. At all four examinations, self-reported quality of relationship with the husband, mother and mother-in-law was ascertained using the Close Persons Questionnaire with respect to emotional support, practical support and negative aspects of the relationship. Antenatal depressive symptoms were defined using the Edinburgh Postnatal Depression Scale. A range of covariates in mixed models was considered including age, education, number of children, family structure, physical health, past emotional problems and stressful life events.
Key findings were as follows: (i) reported emotional and practical support from all three relationships declined over time in the cohort overall; (ii) reported emotional support from the husband, and emotional and practical support from the mother-in-law, declined more strongly in women with antenatal depressive symptoms; (iii) associations between depressive symptoms and worsening spouse relationship were more pronounced in traditional compared with nuclear families.
Antenatal depressive symptoms predicted marked decline in the quality of key relationships over the postnatal period. This may account for some of the contemporaneous associations between depression and worse social support, and may compound the risk of perinatal depression in subsequent pregnancies.
The authors of the earlier version of this book succeeded in accomplishing the goals stated in their preface. Since it was written, Dynamics: Theory and Applications has served as a textbook for teaching graduate students a method of formulating dynamical equations of motion for mechanical systems. The method has proved especially useful for dealing with the complex multibody mechanical systems that in the twentieth and twenty-first centuries have challenged engineers in industry, government, and universities: the Galileo spacecraft sent to Jupiter, the International Space Station, and the robotic manipulator arms aiding astronauts on the Space Shuttle and International Space Station are but a few examples. Kane's method is systematic and easily taught, in a way that enables the student to be conversant with colleagues trained to apply traditional approaches found in the classical literature.
Although the fundamental aspects of the method have not changed during the past three decades, advances and refinements have been made in a number of areas. In certain cases the newer developments facilitate exposition of the topic at hand and lend themselves well to integration with material in the original textbook. The primary purpose of this text, then, is to make the benefits of this progress available for current courses in dynamics.
The preface to the earlier version (which immediately follows this Preface) includes a discussion of the organization of the original book and supporting rationale. Here, we give an overview of the modest alterations made to the earlier structure.
The initial chapter now begins with three brief sections that put the student into position to give a mathematical description of the orientation of a rigid body with respect to a reference frame, when the rigid body has been subjected to successive rotations. Inclusion of these sections provides a formal presentation of topics that typically were covered in classroom discussion. The final section of the first chapter is concerned with differentiation of a scalar function of vectors, which subsequently comes into play in Chapter 6. The original second chapter is divided in two; Chapter 2 deals solely with kinematics, and Chapter 3 is devoted to constraints. The separation focuses attention on the subject of constraints, where there are important distinctions to be made between Kane's method and the classical approaches.
The discipline of dynamics deals with changes of various kinds, such as changes in the position of a particle in a reference frame and changes in the configuration of a mechanical system. To characterize the manner in which some of these changes take place, one employs the differential calculus of vectors, a subject that can be regarded as an extension of material usually taught under the heading of the differential calculus of scalar functions. The extension consists primarily of provisions made to accommodate the fact that reference frames play a central role in connection with many of the vectors of interest in dynamics. A reference frame can be regarded as a massless rigid body, and a rigid body can serve as a reference frame. (A reference frame should not be confused with a coordinate system. Many coordinate systems can be embedded in a given reference frame.) The importance of reference frames in connection with change in a vector can be illustrated by considering the following example. Let A and B be reference frames moving relative to each other, but having one point O in common at all times, and let P be a point fixed in A, distinct from O and thus moving in B. Then the velocity of P in A is equal to zero, whereas the velocity of P in B differs from zero. Now, each of these velocities is a time derivative of the same vector, rOP, the position vector from O to P. Hence, it is meaningless to speak simply of the time derivative of rOP. Clearly, therefore, the calculus used to differentiate vectors must permit one to distinguish between differentiation with respect to a scalar variable in a reference frame A and differentiation with respect to the same variable in a reference frame B.
When working with elementary principles of dynamics, such as Newton's second law or the angular momentum principle, one needs only the ordinary differential calculus of vectors, that is, a theory involving differentiations of vectors with respect to a single scalar variable, generally the time. Consideration of advanced principles of dynamics, such as those presented in later chapters of this book, necessitates, in addition, partial differentiation of vectors with respect to several scalar variables, such as generalized coordinates and motion variables.