The prevalence of osteopenia and osteoporosis after heart transplantation assessed using CT.

OBJECTIVE: Osteoporosis is frequently observed in patients after heart transplantation (HT), although the prevalence long-term post-HT is unknown. Most studies investigating bone mineral density (BD) after HT were performed using dual-energy X-ray absorptiometry. In this study BD, including the prevalence of osteopenia and osteoporosis, was investigated using coronary computed tomography (CCT) long-term post-HT. Moreover, risk factors for abnormal BD were investigated. METHODS: All first CCT scans between February 2018 and June 2020 used for the annual screening for cardiac allograft vasculopathy were included. Retransplantations and scans with not fully imaged vertebrae were excluded. BD was measured as a mean of the BD of three consecutive thoracic vertebrae and categorized into normal BD, osteopenia or osteoporosis. Binary logistic regression was used to find determinants for an abnormal BD. Linear regression was used to explore determinants for the mean Hounsfield unit (HU) value of the BD. RESULTS: In total, 140 patients were included (median age 55.2 [42.9-64.9] years, 51 (36%) female). Time between HT and CT scan was 11.0 [7.3-16.1] years. In total, 80 (57%), 43 (31%), and 17 (12%) patients had a normal BD, osteopenia, or osteoporosis, respectively. Osteoporotic fracture or vertebrae fractures was seen in 11 (8%) patients. Determinants for an abnormal BD were recipient age (OR 1.10 (1.06-1.14), p<0.001) and prednisolone use (OR 3.75 (1.27-11.01), p=0.016). In linear regression, left ventricular assist device use pre-HT (p=0.024) and time since HT (p=0.046) were additional BD determinants. DISCUSSION: Osteopenia and osteoporosis are frequently seen on CCT post-HT. More investigation on appropriate measures to maintain a normal BD in these patients are needed.

[Nutrition and mental disorders during the life span: an overview of scientific evidence]. / Voeding bij psychische aandoeningen gedurende de levensloop; een overzicht van de evidentie.

BACKGROUND: Nutritional interventions are scarcely used in the prevention and treatment of mental disorders.
AIM: To summarize scientific evidence on the relation between nutrition and mental health, across the life span.
METHOD: An overview of the literature based on recent knowledge syntheses, meta-analyses and original studies.
RESULTS: Healthy dietary patterns are associated with a lower risk for depressive symptoms among adults and potentially also among children and adolescents. Dietary interventions can be effective in reducing depressive symptoms among high-risk groups and can have a beneficial effect in the treatment of depression. Meta-analyses of randomised studies have shown that omega-3 fatty acid supplements can be of added value in the treatment of adhd in children and of depression in adults.
CONCLUSION: Promotion of healthy dietary patterns in line with National guidelines for healthy diets is important in the entire spectrum from good mental health to a chronic disorder. More attention for improving healthy dietary patterns among patients with mental disorders can lead to important health gains.

Cortical abnormalities in adults and adolescents with major depression based on brain scans from 20 cohorts worldwide in the ENIGMA Major Depressive Disorder Working Group.

The neuro-anatomical substrates of major depressive disorder (MDD) are still not well understood, despite many neuroimaging studies over the past few decades. Here we present the largest ever worldwide study by the ENIGMA (Enhancing Neuro Imaging Genetics through Meta-Analysis) Major Depressive Disorder Working Group on cortical structural alterations in MDD. Structural T1-weighted brain magnetic resonance imaging (MRI) scans from 2148 MDD patients and 7957 healthy controls were analysed with harmonized protocols at 20 sites around the world. To detect consistent effects of MDD and its modulators on cortical thickness and surface area estimates derived from MRI, statistical effects from sites were meta-analysed separately for adults and adolescents. Adults with MDD had thinner cortical gray matter than controls in the orbitofrontal cortex (OFC), anterior and posterior cingulate, insula and temporal lobes (Cohen's d effect sizes: -0.10 to -0.14). These effects were most pronounced in first episode and adult-onset patients (>21 years). Compared to matched controls, adolescents with MDD had lower total surface area (but no differences in cortical thickness) and regional reductions in frontal regions (medial OFC and superior frontal gyrus) and primary and higher-order visual, somatosensory and motor areas (d: -0.26 to -0.57). The strongest effects were found in recurrent adolescent patients. This highly powered global effort to identify consistent brain abnormalities showed widespread cortical alterations in MDD patients as compared to controls and suggests that MDD may impact brain structure in a highly dynamic way, with different patterns of alterations at different stages of life.

European Network of Trainees in Obstetrics and Gynaecology-ENTOG Exchange 2017: an experience report from Slovenia outlining the different trainee situations around Europe.

PURPOSE: The European Network of Trainees in Obstetrics and Gynaecology (ENTOG) is a non-profit, independent organisation that represents young trainees in obstetrics and gynaecology around Europe. At present, ENTOG has 32 member countries. The organisation was founded in 1997 and shall assure the exchange of experiences between young physicians all over Europe. The aim is to improve the quality of traineeship in all participating countries and consequently enhance the standards for women's healthcare. METHODS: This article reports about the experiences of trainees during the ENTOG Exchange 2017 in Slovenia and gives an overview of the trainee situations in different ENTOG member countries. RESULTS: The ENTOG exchange in Slovenia was a unique opportunity to get insights to the Slovenian medical system. Reflecting about their training situations, the participants found considerable differences in the training of young gynaecologists throughout Europe. CONCLUSIONS: Working on the ENTOG goal of raising the quality of training is still highly relevant. The ENTOG exchange is an excellent way to build a network among trainees and stimulate their commitment to improve women's healthcare in their home countries and beyond.

[Acute kidney failure and renal replacement therapy after colonoscopy in a 63-year-old woman]. / Akutes Nierenversagen mit Dialysepflichtigkeit nach Koloskopie bei einer 63-jährigen Patientin.

A 63-year-old woman presented with intestinal disorder, alternating between obstipation and diarrhoea. Sodium phosphate/diphosphate (Fleet®) was used in preparation for colonoscopy. Within 24 h the patient developed severe hyperphosphatemia and oliguric acute kidney failure with the need of renal replacement therapy. This case illustrates the rare event of phosphate nephropathy after colonoscopy.

Functional connectivity during cognitive control in children with autism spectrum disorder: an independent component analysis.

Restrictive and repetitive behavior in autism may be related to deficits in cognitive control. Here, we aimed to assess functional connectivity during a cognitive control task and compare brain network activity and connectivity in children with autism spectrum disorders (ASD) and typically developing children using a multivariate data-driven approach. 19 high-functioning boys with ASD and 19 age-matched typically developing boys were included in this study. Functional magnetic resonance imaging was performed at 3T during the performance of a cognitive control task (go/no-go paradigm). Functional networks were identified using independent component analysis. Network activity and connectivity was compared between groups and correlated with clinical measures of rigid behavior using multivariate analysis of covariance. We found no differences between the groups in task performance or in network activity. Power analysis indicated that, if this were a real difference, it would require nearly 800 subjects to show group differences in network activity using this paradigm. Neither were there correlations between network activity and rigid behavior. Our data do not provide support for the presence of deficits in cognitive control in children with ASD, or the functional networks supporting this ability.

Sex-related differences in coronary and carotid vessel geometry, plaque composition and shear stress obtained from imaging.

Atherosclerosis manifests itself differently in men and women with respect to plaque initiation, progression and plaque composition. The observed delay in plaque progression in women is thought to be related to the hormonal status of women. Also features associated with the vulnerability of plaques to rupture seem to be less frequently present in women compared to men. Current invasive and non-invasive imaging modalities allow for visualization of plaque size, composition and high risk vulnerable plaque features. Moreover, image based modeling gives access to local shear stress and shear stress-related plaque growth. In this review, current knowledge on sex-related differences in plaque size, composition, high risk plaque features and shear stress related plaque growth in carotid and coronary arteries obtained from imaging are summarized.

Changes in intra- and extracranial carotid plaque calcification: a 2-year follow-up study.

Extra- and intracranial carotid plaque calcification might have plaque-stabilizing effects, yet information on changes in plaque calcification remains scarce. We evaluated changes in carotid plaque calcification over 2 years follow-up in patients with symptomatic carotid artery disease. This study is based on the PARISK-study, a multicenter cohort study, with TIA/minor stroke patients with ipsilateral mild-to-moderate carotid artery stenosis (< 70%). We included 79 patients (25% female, mean age 66 years) who underwent CTA imaging with 2 year interval. We assessed the volume of extra- and intracranial carotid artery calcification (ECAC and ICAC) and calculated the difference between baseline and follow-up ECAC and ICAC volume. We performed multivariable regression analyses to investigate the association between change of ECAC or ICAC with cardiovascular determinants. ECAC. We found increase (46.2%) and decrease (34%) in ECAC volume during 2 year follow-up, both significantly correlation with baseline ECAC volume (OR = 0.72, 95% CI 0.58-0.90 respectively OR = 2.24, 95% CI 1.60-3.13).We found significant correlation for change in ECAC volume with diabetes (ß = 0.46, 95% CI 0.03-0.89) and baseline ECAC volume (ß = 0.81, 95% CI 0.73-0.88). ICAC. We found increase (45.0%) and decrease (25.0%) in ICAC volume. The ICAC decrease was significantly correlated with baseline ICAC volume (OR = 2.17, 95% CI 1.48-3.16), age (OR = 2.00, 95% CI 1.19-3.38) and use of antihypertensive drugs (OR = 3.79, 95% CI 1.20-11.96]).The overall change of ICAC volume was also significantly correlated with diabetes (ß = 0.92, 95% CI 1.59-7.02), use of oral hypoglycemic drugs (ß = 0.86, 95% CI 0.12-1.59) and baseline ICAC volume (ß = 0.71, 95% CI 0.55-0.87). We provide novel insights into the dynamics of carotid plaque calcification in symptomatic stroke patients.

Sex steroids and markers of micro- and macrovascular damage among women and men from the general population.

AIMS: The contribution of sex hormones to micro- and macrovascular damage might differ among women and men. In particular, little is known about the association between sex hormones and small vessel disease. Therefore, we examined the association of total oestradiol, total testosterone, free-androgen index (FAI), dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), and androstenedione levels with micro- and macrovascular diseases. METHODS AND RESULTS: This cross-sectional study included 2950 women and 2495 men from the population-based Rotterdam Study. As proxy of microvascular damage, we measured diameters of retinal arterioles and venules. Markers of macrovascular damage included carotid intima-media thickness and carotid plaque, coronary artery calcification (CAC), and peripheral artery disease. Linear and logistic regression models were used and adjusted for age, cardiovascular risk factors, and years since menopause. Associations with microvasculature: In women, total testosterone [mean difference per 1-unit increase in natural-log transformed total testosterone (95% confidence interval, CI): 2.59 (0.08-5.09)] and androstenedione [4.88 (1.82-7.95)] and in men DHEAS [2.80 (0.23-5.37)] and androstenedione [5.83 (2.19-9.46)] were associated with larger venular caliber. Associations with markers of large vessel disease: In women, higher total testosterone [-0.29 (-0.56 to -0.03)], FAI [-0.33 (-0.56 to -0.10)], and androstenedione levels [-0.33 (-0.64 to -0.02)] were associated with lower CAC burden and FAI [odds ratio (95% CI): 0.82 (0.71-0.94)] was associated with lower prevalence of plaque. CONCLUSION: A more androgenic profile was associated with more microvascular damage in both women and men. Among women, however, higher androgen levels were also associated with less macrovascular damage. Our findings suggest that androgens might have distinct effects on the vasculature, depending on the vascular bed and stages of the atherosclerosis process.

Infective endocarditis in patients after percutaneous pulmonary valve implantation with the stent-mounted bovine jugular vein valve: Clinical experience and evaluation of the modified Duke criteria.

AIMS: Percutaneous pulmonary valve implantation (PPVI) has proven good hemodynamic results. As infective endocarditis (IE) remains a potential complication with limited available clinical data, we reviewed our patient records to improve future strategies of IE prevention, diagnosis and treatment. METHODS: Medical records of all patients diagnosed with Melody® valve IE according to the modified Duke criteria were retrospectively analyzed in three Belgian tertiary centers. RESULTS: 23 IE episodes in 22 out of 240 patients were identified (incidence 2.4% / patient year) with a clear male predominance (86%). Median age at IE was 17.9 years (range 8.2-45.9 years) and median time from PPVI to IE was 2.4 years (range 0.7-8 years). Streptococcal species caused 10 infections (43%), followed by Staphylococcus aureus (n = 5, 22%). In 13/23 IE episodes a possible entry-point was identified (57%). IE was classified as definite in 15 (65%) and as possible in 8 (35%) cases due to limitations of imaging. Echocardiography visualized vegetations in only 10 patients. PET-CT showed positive FDG signals in 5/7 patients (71%) and intracardiac echocardiography a vegetation in 1/1 patient (100%). Eleven cases (48%) had a hemodynamically relevant pulmonary stenosis at IE presentation. Nine early and 6 late percutaneous or surgical re-interventions were performed. No IE related deaths occurred. CONCLUSIONS: IE after Melody® valve PPVI is associated with a relevant need of re-interventions. Communication to patients and physicians about risk factors is essential in prevention. The modified Duke criteria underperformed in diagnosing definite IE, but inclusion of new imaging modalities might improve diagnostic performance.

Repeated oral glucose tolerance tests in women at risk for gestational diabetes mellitus.

OBJECTIVE: Pregnant women with a negative oral glucose tolerance test (OGTT) between 24-28 weeks as part of risk-based screening for gestational diabetes mellitus (GDM) may develop clinical signs or symptoms suggestive for GDM in the third trimester. We aimed to determine the additional yield of repeating an OGTT to detect missed GDM in this group and assess patient characteristics and indications associated with a positive second OGTT. STUDY DESIGN: We conducted a retrospective cohort study of women with a negative OGTT between 24-28 weeks of pregnancy in two hospitals in the Netherlands. Patient characteristics, pregnancy outcomes, OGTT results and indications were compared between women with normal (non-GDM) and abnormal (GDM) results of the second OGTT, using the WHO 1999 criteria (fasting glucose ≥7.0 mmol/L or 2 -h post load ≥7.8 mmol/L). We used receiver operating characteristic (ROC) curve analysis to determine cut-offs for fasting and 2 -h glucose values of the index OGTT that were associated with a positive OGTT in the third trimester. RESULTS: Of 3147 women at risk for GDM, 183 underwent a second OGTT in the third trimester following their regular OGTT at 24-28 weeks. In 43 women (23.5%) GDM was diagnosed based on the second OGTT. A history of GDM was associated with subsequent GDM diagnosis, with an odds ratio of 2.6 (95% CI 1.0-6.3). Both fasting and 2 -h post load glucose values of the index OGTT were significantly higher in women with abnormal OGTT results later in pregnancy. Index OGTT glucose value cut-offs of 4.8 mmol/L (fasting) and 6.5 mmol/L (2 -h) had positive predictive values of 0.32 and 0.47 for a positive OGTT in the third trimester, and negative predictive values of 0.83 and 0.90, respectively. Fetal growth as a clinical symptom for GDM was the most frequent indication for repeating the OGTT, resulting in the diagnosis of GDM in 22.7% of women tested for this indication. CONCLUSION: Repeating an OGTT after initial negative screening results in additional GDM diagnoses. In case of clinical signs, especially in women with additional risk factors such as a history of GDM or higher index OGTT glucose values, repeating an OGTT could be considered.

Immunological consequences of laparoscopic versus open transhiatal resection for malignancies of the distal esophagus and gastroesophageal junction.

BACKGROUND/AIM: Surgery remains the only curative therapy for esophageal cancer. The objective of the current study was to evaluate the impact of laparoscopic transhiatal esophagectomy versus open transhiatal esophagectomy on both inflammatory and immunological responses. METHODS: Seventeen patients undergoing laparoscopic or open surgery were included in the study. The postoperative inflammatory response was assessed by measuring WBC count and CRP, IL-6, IL-8, soluble TNF I and II receptor, and elastase levels. The postoperative immune function was assessed by measuring the monocyte HLA-DR expression. LPS-binding protein (LBP) and bactericidal/permeability-increasing protein (BPI) were measured to evaluate bacterial translocation. RESULTS: The IL-6 level increased significantly more in the patients who received open surgery as compared with the laparoscopic group. Both LBP and BPI increased predominantly in the laparoscopic group as compared with the group who received open surgery. No difference was found in HLA-DR expression between the two groups. CONCLUSION: Although both laparoscopic and conventional esophageal resections result in an activation of the inflammatory response, this study suggests that this response could be less pronounced after the laparoscopic approach. However, in the laparoscopic group higher LBP and BPI levels were seen, suggesting an increased endotoxemia. We postulate that the persistently elevated abdominal pressure results in a loss of mucosal barrier function, resulting in bacterial translocation. The cellular acidification of the cells of the peritoneum induced by CO(2) insufflation, however, blunts the expected inflammatory response.

[Incidental findings on brain MRIPrevalence, clinical management and natural course]. / Toevalsbevindingen bij MRI-onderzoek van de hersenen.

OBJECTIVE: Diagnostic brain imaging has been performed increasingly since the 1990s. A direct result of this is the rise in the detection of incidental findings. The objective of this study is to provide insight into the prevalence, clinical relevance and natural course of incidental findings on brain magnetic resonance imaging (MRI) scans. DESIGN: Prospective cohort study. METHOD: Within the framework of the Rotterdam study, 5800 participants underwent a brain MRI scan during the period 2005-2014. Their average age was 64.9 years, and 55.1% were female. Trained reviewers and experienced neuroradiologists evaluated all scans for clinically relevant incidental findings. We calculated the prevalence of abnormalities discovered, and investigated which clinical management followed in those participants who were referred. On the basis of subsequent scans within the framework of the Rotterdam study we investigated the natural course of findings found in participants who were not referred. RESULTS: There were incidental findings in 549 of 5800 (9.5%) participants. The most common abnormalities were meningiomas in 143 participants (2.5%) and aneurysms in 134 participants (2.3%). A total of 188 participants (3.2%) were referred to a medical specialist, who chose for a wait-and-see policy or discharge after the initial consultation in 144 participants (76.6%). The majority of meningiomas and aneurysms not referred or untreated, remained stable in size during the average follow-up period of 48-60 months. CONCLUSION: Incidental findings on brain MRI are made relatively frequently in people of middle age or older. In 3% of these people these findings are reason for additional clinical evaluation, mostly without further clinical consequences.

Population imaging in neuroepidemiology.

Neuroepidemiologic studies have traditionally focused on studying associations between determinants and neurologic outcomes, while treating the pathway in between both as a "black box." With the rise of noninvasive, advanced neuroimaging techniques, it has become possible to directly study brain changes occurring in this "black box." This importantly aids to unravel disease pathways, find new markers of disease, or identify subjects at risk of disease. Imaging in neuroepidemiologic studies is also called population neuroimaging. This chapter discusses the rationale of population neuroimaging, the different imaging modalities that can be applied, and the various ways to extract visual or quantitative information from these images. Population neuroimaging is a fast-progressing field, partly due to new techniques and partly due to the growing need for collaboration, harmonization, and standardization among studies. Considerations for future applications of imaging in neuroepidemiology are discussed against this background.

Structural Brain Alterations in Community Dwelling Individuals with Chronic Joint Pain.

BACKGROUND AND PURPOSE: Central sensitization in chronic pain involves structural brain changes that influence vulnerability to pain. Identifying brain regions involved in pain processing and sensitization can provide more insight into chronic pain. This study examines structural brain changes in chronic pain and experimental pain in a large population-based study. MATERIALS AND METHODS: For 3892 participants in the Rotterdam study, global and regional MR imaging brain volumes were automatically segmented and quantified. Chronic joint pain was defined as pain for more than half of all days during the past 6 weeks. Heat pain thresholds were measured in a subset of 1538 individuals. The association between the presence of chronic joint pain and global and lobar brain volumes was studied. Subsequently, literature was reviewed and the association of chronic pain and heat pain thresholds with 11 brain regions associated with musculoskeletal pain in previous publications was studied. RESULTS: Total gray matter volume was smaller in women with chronic pain (ß = -0.066, P = .016). This effect was primarily driven by lower gray matter volume in the temporal lobe (ß = 0.086, P = .005), the frontal lobe (ß = -0.060, P = .039), and the hippocampus (ß = -0.099, P = .002). In addition, we observed that a lower heat pain threshold was associated with smaller volumes of the hippocampus (ß = 0.017, P = .048), the thalamus (ß = 0.018, P = .009), and the anterior cingulate cortex (ß = -0.016, P = .037). In men, no significant associations were observed. CONCLUSIONS: The primary identified brain areas, the temporal and frontal lobes and the hippocampus, indicated involvement of emotional processing. The volumetric differences found indicated a sex-specific neuroplasticity in chronic pain. These results emphasized sex-specific and multidisciplinary pain treatment.

Further characterization of estrogen binding to rat testis cytosol.

Binding of estradiol (E2), estriol (E3), RU16117, and moxestrol to testis cytosol from adult male rats was investigated. High-affinity binding sites were identified in the 8-9S region of sucrose density gradients; a second, high-capacity binding component in the 4S region was probably due to contamination with serum. Thermodynamic properties of the testicular estrogen binding site were quite similar to those of the uterine receptor. E2 had the highest affinity for testicular cytosol binding sites (Ka: E2 much greater than moxestrol greater than E3 greater than RU16117). Comparison of association rate (E2 greater than E3 greater than moxestrol = RU16117) and dissociation rate constants (E3 = RU16117 greater than E2 much greater than moxestrol) as well as studies in vivo revealed moxestrol as a long-acting and RU16117 as a short-acting compound. This difference may be useful for evaluation of the mediation of estrogen effects in the rat testis.

Social comparison preferences among cancer patients as related to neuroticism and social comparison orientation.

Effects of neuroticism and social comparison orientation on social comparison among cancer patients were examined. A computer program that enabled patients to access information about fellow patients' disease-related experiences was developed. Patients selected more interviews concerning more as compared to less fortunate others, spent more time reading, and showed more favorable reactions to such information. Individuals with a strong comparison orientation in particular tended to engage in and to respond to social comparison. Neuroticism was associated with higher interest in social comparison and with less favorable reactions, regardless of its direction. High-neurotic individuals reacted more positively to upward than to downward comparisons, whereas the reactions of low-neurotic individuals were unaffected by comparison direction. The latter effect was replicated using a general affect measure, but solely among individuals with a strong comparison orientation.

Differential down-regulation and induction responses of testicular steroidogenic cytochromes P-450(cscc) and P-450(C17 alpha) to human choriogonadotropin.

Evidence is presented that the regulation of the cytochrome P-450(C17 alpha) of the steroid-17 alpha-monooxygenase and of the cytochrome P-450(cscc) of the cholesterol-monooxygenase by human choriogonadotropin (hCG) in vivo is mediated by differential mechanisms in the adult rat testis. An initial down-regulation of the cytochrome P-450(C17 alpha) but not of the P-450(cscc) can be demonstrated. Furthermore, induction of the cytochrome P-450(cscc) requires exposure to higher hCG doses (32% of the maximal induction rate of 43.7 pmol/(testis x d) are achieved with 4IU hCG/single dose) than induction of the P-450(C17 alpha) (59% of the maximal induction rate of 48.4 pmol/(testis x d) with 4IU hCG/single dose). Finally, induction of cytochrome P-450(cscc) starts faster after initiation of hCG treatment than induction of P-450(C17 alpha).

An intelligent computer-assisted instruction system designed for rural health workers in developing countries.

This paper describes an intelligent computer-assisted instruction system that was designed for rural health workers in developing countries. This system, called Consult-EAO, includes an expert module and a coaching module. The expert module, which is derived from the knowledge-based decision support system Tropicaid, covers most of medical practice in developing countries. It allows for the creation of outpatient simulations without the help of a teacher. The student may practice his knowledge by solving problems with these simulations. The system gives some initial facts and controls the simulation during the session by guiding the student toward the most efficient decisions. All student answers are analyzed and, if necessary, criticized. The messages are adapted to the situation due to the pedagogical rules of the coaching module. This system runs on PC-compatible computer.

Economic consequences of an aging population.

PIP: Europe and Japan are experiencing the aging of their populations. Aging implies a restructuring of the economy. Political issues which arise in an aging society include 1) a voting majority for the interests of the elderly, 2) a voting majority of females, 3) the domination of the decision power in corporate and similar ruling bodies, and 4) unemployment or a long wait for promotion for younger people. Economic issues of an aging society include 1) population aging often occurs under reduced rates of growth of per capita national income, 2) the relative economic status of the elderly very much depends on the currently existing tax transfer systems, and 3) the income of families whose head is over age 65 has generally been more unequally distributed than the income for younger families. Issues concerning the labor supply of the elderly include 1) the availability of pension income and health limitations strongly influence decisions to retire and 2) older workers become disheartened and choose early retirement when facing bad reemployment prospects. In general, population aging is likely to have its most substantive effect on the overall level of productivity in an economy where technical knowledge is changing rapidly and strong competition necessitates a high degree of adaptability of the labor force.^ieng