Low-dose growth hormone treatment with diet restriction accelerates body fat loss, exerts anabolic effect and improves growth hormone secretory dysfunction in obese adults

Obesity and Cardiovascular Risk: Systematic Intervention Is the Key for Prevention

Obesity is a serious public health issue and associated with an increased risk of cardiovascular disease events and mortality. The risk of cardiovascular complications is directly related to excess body fat mass and ectopic fat deposition, but also other obesity-related complications such as pre-type 2 diabetes, obstructive sleep apnoea, and non-alcoholic fatty liver diseases. Body mass index and waist circumference are used to classify a patient as overweight or obese and to stratify cardiovascular risk. Physical activity and diet, despite being key points in preventing adverse events and reducing cardiovascular risk, are not always successful strategies. Pharmacological treatments for weight reduction are promising strategies, but are restricted by possible safety issues and cost. Nonetheless, these treatments are associated with improvements in cardiovascular risk factors, and studies are ongoing to better evaluate cardiovascular outcomes. Bariatric surgery is effective in reducing the incidence of death and cardiovascular events such as myocardial infarction and stroke. Cardiac rehabilitation programs in obese patients improve cardiovascular disease risk factors, quality of life, and exercise capacity. The aim of this review was to critically analyze the current role and future aspects of lifestyle changes, medical and surgical treatments, and cardiac rehabilitation in obese patients, to reduce cardiovascular disease risk and mortality, and to highlight the need for a multidisciplinary approach to improving cardiovascular outcomes.

Dementia Incidence, APOE Genotype, and Risk Factors for Cognitive Decline in Aboriginal Australians: A Longitudinal Cohort Study

BACKGROUND AND OBJECTIVES

Aboriginal Australians are disproportionately affected by dementia, with incidence in remote populations approximately double non-Indigenous populations. This study aimed to identify dementia incidence and risk factors in Aboriginal Australians residing in urban areas, which are currently unknown.

METHODS

A population-based cohort of Aboriginal Australians aged 60+ was assessed at baseline and 6-year follow-up. Life-course risk factors (baseline) were examined for incident dementia or mild cognitive impairment (MCI) using logistic regression analyses; adjustments were made for age. APOE genotyping was available for 86 people.

RESULTS

Data were included from 155 participants aged 60-86 years (mean=65.70, SD=5.65; 59 male). There were 16 incident dementia cases (age-standardised rate 35.97/1,000 person-years, 95% CI 18.34-53.60); and 36 combined incident MCI and dementia cases. Older age (OR 2.29, 1.42-3.70), male sex (OR 4.14, 1.60-10.77), unskilled work history (OR 5.09, 1.95-13.26), polypharmacy (OR 3.11, 1.17-8.28), and past smoking (OR 0.24, 0.08-0.75) were associated with incident MCI/dementia in the final model. APOE ε4 allele frequency was 24%; heterozygous or homozygous ε4 was associated with incident MCI/dementia (bivariate OR 3.96, 1.25-12.50).

DISCUSSION

These findings provide the first evidence for higher dementia incidence in Aboriginal Australians from urban areas, where the majority of Aboriginal people reside. This study also sheds light on sociodemographic, health and genetic factors associated with incident MCI/dementia at older ages in this population, which is critical for targeted prevention strategies.

Illiteracy, dementia risk, and cognitive trajectories among older adults with low education

OBJECTIVE

To investigate whether illiteracy was associated with greater risk of prevalent and incident dementia and more rapid cognitive decline among older adults with low education.

METHODS

Analyses included 983 adults (≥65 years old, ≤4 years of schooling) who participated in a longitudinal community aging study. Literacy was self-reported ("Did you ever learn to read or write?"). Neuropsychological measures of memory, language, and visuospatial abilities were administered at baseline and at follow-ups (median [range] 3.49 years [0-23]). At each visit, functional, cognitive, and medical data were reviewed and a dementia diagnosis was made using standard criteria. Logistic regression and Cox proportional hazards models evaluated the association of literacy with prevalent and incident dementia, respectively, while latent growth curve models evaluated the effect of literacy on cognitive trajectories, adjusting for relevant demographic and medical covariates.

RESULTS

Illiterate participants were almost 3 times as likely to have dementia at baseline compared to literate participants. Among those who did not have dementia at baseline, illiterate participants were twice as likely to develop dementia. While illiterate participants showed worse memory, language, and visuospatial functioning at baseline than literate participants, literacy was not associated with rate of cognitive decline.

CONCLUSION

We found that illiteracy was independently associated with higher risk of prevalent and incident dementia, but not with a more rapid rate of cognitive decline. The independent effect of illiteracy on dementia risk may be through a lower range of cognitive function, which is closer to diagnostic thresholds for dementia than the range of literate participants.

Growth Hormone's Effect on Adipose Tissue: Quality versus Quantity

Obesity is an excessive accumulation or expansion of adipose tissue (AT) due to an increase in either the size and/or number of its characteristic cell type, the adipocyte. As one of the most significant public health problems of our time, obesity and its associated metabolic complications have demanded that attention be given to finding effective therapeutic options aimed at reducing adiposity or the metabolic dysfunction associated with its accumulation. Growth hormone (GH) has therapeutic potential due to its potent lipolytic effect and resultant ability to reduce AT mass while preserving lean body mass. However, AT and its resident adipocytes are significantly more dynamic and elaborate than once thought and require one not to use the reduction in absolute mass as a readout of efficacy alone. Paradoxically, therapies that reduce GH action may ultimately prove to be healthier, in part because GH also possesses potent anti-insulin activities along with concerns that GH may promote the growth of certain cancers. This review will briefly summarize some of the newer complexities of AT relevant to GH action and describe the current understanding of how GH influences this tissue using data from both humans and mice. We will conclude by considering the therapeutic use of GH or GH antagonists in obesity, as well as important gaps in knowledge regarding GH and AT.

Growth hormone-releasing hormone is produced by adipocytes and regulates lipolysis through growth hormone receptor

BACKGROUND

Growth hormone-releasing hormone (GHRH) has a crucial role in growth hormone (GH) secretion, but little is known about its production by adipocytes and its involvement in adipocyte metabolism.

OBJECTIVES

To determine whether GHRH and its receptor (GHRH-R) are present in human adipocytes and to study their levels in obesity. Also, to analyze the effects of GHRH on human adipocyte differentiation and lipolysis.

METHODS

GHRH/GHRH-R and GH/GH-R mRNA expression levels were analyzed in human mature adipocytes from non-obese and morbidly obese subjects. Human mesenchymal stem cells (HMSC) were differentiated to adipocytes with GHRH (10^-14-10^-8 M). Adipocyte differentiation, lipolysis and gene expression were measured and the effect of GH-R silencing was determined.

RESULTS

Mature adipocytes from morbidly obese subjects showed a higher expression of GHRH and GH-R, and a lower expression of GHRH-R and GH than non-obese subjects (P<0.05). A total of 10^-14-10^-10 M GHRH induced an inhibition of lipid accumulation and PPAR-γ expression (P<0.05), and an increase in glycerol release and HSL expression (P<0.05) in human differentiated adipocytes. A total of 10^-12-10^-8 M GHRH decreased GHRH-R expression in human differentiated adipocytes (P<0.05). A total of 10^-10-10^-8 M GHRH increased GH and GH-R expression in human differentiated adipocytes (P<0.05). The effects of GHRH at 10^-10 M on adipocyte differentiation and lipolysis were blocked when GH-R expression was silenced.

CONCLUSIONS

GHRH and GHRH-R are expressed in human adipocytes and are negatively associated. GHRH at low doses may exert an anti-obesity effect by inhibiting HMSC differentiation in adipocytes and by increasing adipocyte lipolysis in an autocrine or paracrine pathway. These effects are mediated by GH and GH-R.

Obesity, growth hormone and exercise

Growth hormone (GH) is regulated, suppressed and stimulated by numerous physiological stimuli. However, it is believed that obesity disrupts the physiological and pathological factors that regulate, suppress or stimulate GH release. Pulsatile GH has been potently stimulated in healthy subjects by both aerobic and resistance exercise of the right intensity and duration. GH modulates fuel metabolism, reduces total fat mass and abdominal fat mass, and could be a potent stimulus of lipolysis when administered to obese individuals exogenously. Only pulsatile GH has been shown to augment adipose tissue lipolysis and, therefore, increasing pulsatile GH response may be a therapeutic target. This review discusses the factors that cause secretion of GH, how obesity may alter GH secretion and how both aerobic and resistance exercise stimulates GH, as well as how exercise of a specific intensity may be used as a stimulus for GH release in individuals who are obese. Only five prior studies have investigated exercise as a stimulus of endogenous GH in individuals who are obese. Based on prior literature, resistance exercise may provide a therapeutic target for releasing endogenous GH in individuals who are obese if specific exercise programme variables are utilized. Biological activity of GH indicates that this may be an important precursor to beneficial changes in body fat and lean tissue mass in obese individuals. However, additional research is needed including what molecular GH variants are acutely released and involved at target tissues as a result of different exercise stimuli and what specific exercise programme variables may serve to stimulate GH in individuals who are obese.

The GH/IGF-1 axis in obesity: pathophysiology and therapeutic considerations

Obesity has become one of the most common medical problems in developed countries, and this disorder is associated with high incidences of hypertension, dyslipidaemia, cardiovascular disease, type 2 diabetes mellitus and specific cancers. Growth hormone (GH) stimulates the production of insulin-like growth factor 1 in most tissues, and together GH and insulin-like growth factor 1 exert powerful collective actions on fat, protein and glucose metabolism. Clinical trials assessing the effects of GH treatment in patients with obesity have shown consistent reductions in total adipose tissue mass, in particular abdominal and visceral adipose tissue depots. Moreover, studies in patients with abdominal obesity demonstrate a marked effect of GH therapy on body composition and on lipid and glucose homeostasis. Therefore, administration of recombinant human GH or activation of endogenous GH production has great potential to influence the onset and metabolic consequences of obesity. However, the clinical use of GH is not without controversy, given conflicting results regarding its effects on glucose metabolism. This Review provides an introduction to the role of GH in obesity and summarizes clinical and preclinical data that describe how GH can influence the obese state.

Treatment of Obesity Using GH

The obesity epidemic calls for complementary treatment possibilities in addition to lifestyle changes. One of the important regulators of lipid homeostasis is growth hormone (GH). Clinical trials have tested if GH can reduce obesity in humans. The mechanisms underlying the response to GH administration have also been investigated in animal models of human obesity. A literature search yielded 19 randomized placebo-controlled clinical studies and several animal studies investigating chronic GH treatment of obesity. Significant effects were found in some of the larger trials. One clinical trial showed significantly increased weight loss due to GH treatment, and in seven trials, a significant reduction of fat mass was found. The improvements observed were modest, but even minor improvements have been shown to be beneficial, especially if the reduction in fat mass includes visceral adipose tissue, as was reported in three of six trials. In principle, animal data support the clinical observations although the reduction of fat mass was more dramatic than observed in humans. The mechanisms resulting in lipid mobilization most likely include adipose tissue lipo-protein lipase (LPL) inhibition and antagonization of the anti-lipolytic activity of insulin. By feeding a restricted amount of a high fat diet to GH exposed rats hyper-insulinemia was avoided, loss of body fat was accelerated and metabolic markers were improved. Provision of a diet suitable for the metabolic conditions during GH treatment shows promise for improving metabolic control and can perhaps increase the efficacy and/or widen the therapeutic window of GH.

Regulation of Peptide YY Levels by Age, Hormonal, and Nutritional Status

OBJECTIVE

Peptide YY (PYY) 3-36 has recently been recognized as an important gut hormone that influences food intake. Peripheral injections of PYY 3-36 in rats inhibit food intake in experimental animals as well as in lean and obese human subjects. This hormone has been suggested as an attractive therapeutic option for obesity. The aim of this study was to assess the influence of age, sex, thyroid status, growth hormone (GH), pregnancy, and food restriction on PYY levels in rat.

RESEARCH METHODS AND PROCEDURES

We determined plasma PYY levels in all experimental sets.

RESULTS

PYY levels were influenced by age, with the highest hormone levels achieved in early postnatal life (day 10) and decreasing thereafter. PYY levels were also dependent on thyroid hormone status being decreased in hyperthyroid rats. Exogenous GH administration led to a clear-cut decrease in PYY levels in both normal and GH-deficient rats. Acute food deprivation or chronic food restriction led to decreased PYY levels in virgin and pregnant rats. In pregnant rats with food available ad libitum, PYY levels were enhanced at late gestation.

DISCUSSION

Our observations indicate that PYY levels are influenced by age, thyroid hormones, and GH. These data indicate that PYY could be involved in the changes of food intake associated with these conditions. The PYY levels observed in acute and chronic food-restricted rats indicate that, in situations of decreased energy intake, the lower PYY levels could serve to disinhibit central pathways and facilitate food intake.

Increasing prevalence of dementia among very old people

BACKGROUND

it is unknown whether the age-specific prevalence of dementia among the very old changes over time.

METHODS

this study compares the prevalence of dementia in two population-based cross-sectional samples of very old people in northern Sweden in 2000-02 and in 2005-07. In total, 430 individuals aged 85 and older (mean age 89.5 years, 71.4% women) were evaluated for dementia in the first cross-section and 465 individuals (mean age 90.2 years, 70.9% women) in the second. Trained assessors performed assessments and interviews during home visits and collected information from carers, relatives and medical records. Dementia was diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, fourth edition criteria.

RESULTS

the prevalence of dementia in the total sample was 26.5% in 2000-02 and 37.2% in 2005-07 (P = 0.001). There was also an increase in the prescription of different antihypertensive agents, antilipemic agents and choline esterase inhibitors, and more people had had heart surgery in the later sample.

CONCLUSIONS

in this sample of very old people, an increase in the age-specific prevalence of dementia was detected over 5 years. Possible reasons for this may be extended survival among individuals with risk factors for dementia and among individuals with established dementia.

Is there an association between low-to-moderate alcohol consumption and risk of cognitive decline?

The authors evaluated the association of low-to-moderate alcohol consumption with risk of cognitive decline in a census-based cohort study of men and women aged ≥55 years conducted in Zaragoza, Spain (1994-1999). Participants free of dementia at baseline (N = 3,888) were examined after 2.5 and 4.5 years of follow-up. Information on alcohol intake was collected with the EURODEM Risk Factors Questionnaire and the History and Aetiology Schedule. The study endpoint was severe cognitive decline, defined as loss of ≥1 point/year on the Mini-Mental State Examination or a diagnosis of incident dementia (Diagnostic and Statistical Manual of Mental Disorders: DSM-IV, Text Revision criteria). Compared with those for abstainers, the multivariate-adjusted odds ratios for severe cognitive decline for male drinkers of <12 g alcohol/day, drinkers of 12-24 g alcohol/day, and former drinkers were 0.61 (95% confidence interval (CI): 0.31, 1.20), 1.19 (95% CI: 0.61, 2.32), and 1.03 (95% CI: 0.59, 1.82), respectively. The corresponding odds ratios for women were 0.88 (95% CI: 0.45, 1.72), 2.38 (95% CI: 0.98, 5.77), and 1.03 (95% CI: 0.48, 2.23). This study did not support the hypothesis that low-to-moderate alcohol consumption prevents cognitive decline. The inverse association between low-to-moderate alcohol intake and cognitive decline observed in other studies may have been due to inclusion of former drinkers in the abstainers reference category.

Obesity, growth hormone and weight loss

Growth hormone (GH) is the most important hormonal regulator of postnatal longitudinal growth in man. In adults GH is no longer needed for longitudinal growth. Adults with growth hormone deficiency (GHD) are characterised by perturbations in body composition, lipid metabolism, cardiovascular risk profile and bone mineral density. It is well established that adult GHD usually is accompanied by an increase in fat accumulation and GH replacement in adult patients with GHD results in reduction of fat mass and abdominal fat mass in particular. It is also recognized that obesity and abdominal obesity in particular results in a secondary reduction in GH secretion and subnormal insulin-like growth factor-I (IGF-I) levels. The recovery of the GH IGF-I axis after weight loss suggest an acquired defect, however, the pathophysiologic role of GH in obesity is yet to be fully understood. In clinical studies examining the efficacy of GH in obese subjects very little or no effect are observed with respect to weight loss, whereas GH seems to reduce total and abdominal fat mass in obese subjects. The observed reductions in abdominal fat mass are modest and similar to what can be achieved by diet or exercise interventions.

High medical co-morbidity and family history of dementia is associated with lower cognitive function in older patients

BACKGROUND

Risk factors for cognitive decline in ageing are multifactorial, including medical co-morbidities and familial genetic risk.

OBJECTIVES

To assess the effect of medical co-morbidity and family history of dementia on cognitive performance in older outpatients of family practitioners.

METHODS

Analysis of 535 outpatients from 11 practices aged 65 and older, without a diagnosis of dementia. Information on medical co-morbidities, family history of dementia and cognitive test data were obtained.

RESULTS

Patients were classified into high or low medical co-morbidities (<7 versus >8) and positive or negative family history of dementia. After controlling for age, education, gender and depression, global cognitive test scores, as well as memory, executive function, spatial ability and attention were significantly lower for persons having a high number of medical co-morbidities. Cognitive test scores were not significantly different for persons with or without a family history of dementia. A significant interaction between medical co-morbidities and family history of dementia was observed for the global cognitive score, executive function and spatial ability. Those persons with a high number of medical co-morbidities and positive family history of dementia had the lowest performance. Separate regression analysis assessing individual disease risk factors (e.g. hypertension and diabetes) did not find any relationship between specific medical variables and cognitive test scores for any of the subgroups.

CONCLUSIONS

A high number of medical co-morbidities in addition to a reported family history of dementia are particularly detrimental to cognitive performance in elderly non-demented family practice patients.

Lower growth hormone and higher cortisol are associated with greater visceral adiposity, intramyocellular lipids, and insulin resistance in overweight girls

Although body composition, insulin sensitivity, and lipids are markedly altered in overweight adolescents, hormonal associations with these parameters have not been well characterized. Growth hormone (GH) deficiency and hypercortisolemia predispose to abdominal adiposity and insulin resistance, and GH secretion is decreased in obese adults. We hypothesized that low-peak GH on the GH-releasing hormone (GHRH)-arginine stimulation test and high cortisol in overweight adolescents would be associated with higher regional fat, insulin resistance, and lipids. We examined the following parameters in 15 overweight and 15 bone age-matched control 12- to 18-yr-old girls: 1) body composition using dual-energy X-ray absorptiometry and MR [visceral and subcutaneous adipose tissue at L(4)-L(5) and soleus intramyocellular lipid ((1)H-MR spectroscopy)], 2) peak GH on the GHRH-arginine stimulation test, 3) mean overnight GH and cortisol, 4) 24-h urinary free cortisol (UFC), 5) fasting lipids, and 6) an oral glucose tolerance test. Stepwise regression was the major tool employed to determine relationships between measured parameters. Log peak GH on the GHRH-arginine test was lower (P = 0.03) and log UFC was higher (P = 0.02) in overweight girls. Log mean cortisol (overnight sampling) was associated positively with subcutaneous adipose tissue and, with body mass index standard deviation score, accounted for 92% of its variability, whereas log peak GH and body mass index standard deviation score accounted for 88% of visceral adipose tissue variability and log peak GH for 34% of the intramyocellular lipid variability. Log mean cortisol was independently associated with log homeostasis model assessment of insulin resistance, LDL, and HDL and explained 49-59% of the variability. Our data indicate that lower peak GH and higher UFC in overweight girls are associated with visceral adiposity, insulin resistance, and lipids.

Dementia of the Alzheimer type

Dementia of the Alzheimer type is a progressive, fatal neurodegenerative condition characterized by deterioration in cognition and memory, progressive impairment in the ability to carry out activities of daily living, and a number of neuropsychiatric symptoms. This narrative review summarizes the literature regarding descriptive epidemiology, clinical course, and characteristic neuropathological changes of dementia of the Alzheimer type. Although there are no definitive imaging or laboratory tests, except for brain biopsy, for diagnosis, brief screening instruments and neuropsychiatric test batteries used to assess the disease are discussed. Insufficient evidence exists for the use of biomarkers in clinical practice for diagnosis or disease management, but promising discoveries are summarized. Optimal treatment requires both nonpharmacological and pharmacological interventions, yet none have been shown to modify the disease's clinical course. This review describes the current available options and summarizes promising new avenues for treatment. Issues related to the care of persons with dementia of the Alzheimer type, including caregiver burden, long-term care, and the proliferation of dementia special care units, are discussed. Although advances have been made, more research is needed to address the gaps in our understanding of the disease.

Current and future perspectives on recombinant growth hormone for the treatment of obesity

The similarities between patients with untreated growth hormone (GH) deficiency and those with the cardiometabolic syndrome and the beneficial effects of recombinant human GH (rhGH) on body composition have led to the hypothesis that rhGH treatment may have utility in obesity. GH release is reduced in the setting of obesity, primarily due to hyperinsulinism and increased free fatty acid levels. We reviewed the outcomes of 23 clinical studies carried out between 1987 and 2006 that examined the effects of rhGH administration in the obese state. Typically, changes in overall body weight do not occur with rhGH therapy; however, assessment of body composition demonstrates reductions in visceral abdominal fat. Data on the effects of rhGH on lipid and carbohydrate metabolic profiles in obese patients are less clear-cut, with a subset of studies showing a beneficial effect and others a neutral effect. Given the increasing burden of obesity in the general population and the current paucity of effective therapies, it is useful to consider the data on rhGH and obesity from a clinical perspective to highlight potential treatment strategies that harness the somatotropic axis.

Modulation of glucocorticoid metabolism by the growth hormone - IGF-1 axis

The growth hormone-insulin-like growth factor 1 (GH-IGF-1) axis plays an important role in modulating the peripheral metabolism of glucocorticoids mainly through its effect on the isoenzyme 11 beta-hydroxysteroid dehydrogenase 1 (11beta-HSD1) which, in vivo, functions as a reductase catalysing the conversion of cortisone to cortisol. Several in vivo and ex vivo studies have shown that the GH-IGF-I system inhibits the expression and activity of 11beta-HSD1 in adipose tissues and the liver resulting in reduced local regeneration of cortisol. This interaction has clinically significant implications as it may at least partly explain the phenotypes of acromegaly and adult GH deficiency and the effects that treatment of these conditions has on body composition. In addition, by accelerating the peripheral metabolism of cortisol, GH therapy may precipitate adrenal insufficiency in susceptible hypopituitary patients, and endocrinologists should be mindful of this phenomenon when starting hypopituitary patients on GH replacement therapy.

The role of peptide YY in regulating glucose homeostasis

The gut-derived hormone peptide YY (PYY) is most commonly known for its effect on satiety, decreasing food intake and body weight in animals and humans. However, PYY is also involved in a wide range of digestive functions including regulating insulin secretion and glucose homeostasis. Over the last few years, there have been several interesting clinical and animal studies investigating the role of PYY in glucose homeostasis. This review aims to present an updated summary of findings over the last few decades highlighting the role of PYY in regulating insulin output and insulin sensitivity, and the potential mechanisms involved.

Marital status and living situation during a 5-year period are associated with a subsequent 10-year cognitive decline in older men: the FINE Study

We investigate the association between marital status and living situation (over 5 years) on 10-year subsequent cognitive decline. The study population consisted of 1,042 men aged 70-89 years in 1990, who participated in the longitudinal Finland, Italy, the Netherlands Elderly (known as FINE) Study. We measured cognition by using the Mini-Mental State Examination, and we assessed marital status (married vs unmarried) and living situation (living with others vs living alone) with a standardized questionnaire. We performed repeated measurement analyses and made adjustments for age, education, country, smoking, alcohol, chronic diseases, marital status or living situation, and baseline cognition. Men who lost a partner, who were unmarried, who started to live alone, or who lived alone during the 5-year period had at least a two times stronger subsequent cognitive decline compared with men who were married or who lived with someone in those years.

Sex differences after all those years? Heritability of cognitive abilities in old age

We investigated sex differences in genetic and environmental effects on cognitive abilities among older adult twins. We drew participants from the Swedish Twin Registry; our sample included 647 twin pairs. Our cognitive measures included Synonyms, Block Design, Digit Span, Thurstone's Picture Memory, Symbol Digit, and general cognitive ability tests. Higher age was related to lower performance in all cognitive measures, except synonyms. For digit span forward, symbol digit, and general cognitive ability tasks, there was a Sex x Age interaction, with greater deficits in the performance of women compared with those of men at higher ages. We found no sex-specific genetic influences. In other words, the same genetic effects were operating for men and women. Furthermore, the magnitude of genetic effect was similar for men and women.

Complexity of work and risk of Alzheimer's disease: a population-based study of Swedish twins

We examined the association between risk of dementia or Alzheimer's disease (AD) and occupation by using measures of complexity of work with data, people, and things. The study included 10,079 members of the population-based Swedish Twin Registry who were participants in the HARMONY study. We diagnosed dementia by means of a two-stage procedure--cognitive impairment screening followed by full clinical evaluation. We analyzed data with case-control and cotwin control designs. The cotwin control design provides control over genetic and familial factors. In the case-control study, controlling for age, gender, and level of education, we found that more complex work with people was associated with reduced risk of AD. Greater complexity of work with people and data was protective in twin pairs discordant for AD. Findings suggest that greater complexity of work, and particularly complex work with people, may reduce the risk of AD.

Cardiovascular risk in aging and obesity: is there a role for GH

GH has significant impact in adults. In fact, patients with the GH deficiency (GHD) syndrome are now recognized as having an increased cardiovascular risk. The effects of human aging on GH secretion have been evaluated by a number of researchers. Studies of 24 h secretion of GH have shown variable reductions in most 24-h GH secretory parameters in middle-aged and in older men and women, resulting in a decrease in plasma levels of its anabolic mediator IGF-I. Obesity is also associated with several endocrine and metabolic abnormalities. These include decreased serum GH concentrations, reduced GH half-life, frequency of GH secretory episodes and daily GH production rate. The mechanism of the low GH in obesity is not completely understood nor is it clear whether its relationship with visceral adiposity is causal. The aim of this article will be to review the available clinical data concerning the potential involvement of "subclinical" or perhaps better "functional" GHD, which is observed in aging and obesity, in the increase in cardiovascular risk which characterizes these two conditions.

Does participation in leisure activities lead to reduced risk of Alzheimer's disease? A prospective study of Swedish twins

This study examined whether participation in leisure activities during early and middle adulthood was associated with reduced risk of Alzheimer's disease. The sample consisted of 107 same-sex twin pairs discordant for dementia and for whom information on leisure activities was self-reported more than 20 years prior to clinical evaluation. A factor analysis of these activities yielded three activity factors: intellectual-cultural, self-improvement, and domestic activity. Matched-pair analyses compared activities within the discordant twin pairs while controlling for level of education. For the total sample, participation in a greater overall number of leisure activities was associated with lower risk of both Alzheimer's disease and dementia in general. Greater participation in intellectual-cultural activities was associated with lower risk of Alzheimer's disease for women, although not for men.

Effects of growth hormone administration in human obesity

OBJECTIVE

To summarize the reports in the literature regarding the effect of growth hormone (GH) treatment of obesity.

RESEARCH METHODS AND PROCEDURES

Clinical trials of GH treatment of obese adults were reviewed and summarized. Specifically, information regarding the effects of GH on body fat and body fat distribution, glucose tolerance/insulin resistance, and adverse consequences of treatment were recorded.

RESULTS

GH administered together with hypocaloric diets did not enhance fat loss or preserve lean tissue mass. No studies provided strong evidence for an independent beneficial effect of GH on visceral adiposity. In all but one study, glucose tolerance during GH treatment suffered relative to placebo.

CONCLUSION

The bulk of studies indicate little or no beneficial effects of GH treatment of obesity despite the low serum GH concentrations associated with obesity.

Effect of recombinant human growth hormone in the treatment of visceral fat accumulation in HIV infection

HIV-associated lipodystrophy often includes excess accumulation of visceral fat. Recombinant human growth hormone (rhGH) is a potential treatment for the excess visceral fat. Prospective, open-label trials of 24 weeks of rhGH 6 mg/d and 24 weeks of 4 mg every other day were conducted with an intervening washout period of 12 weeks. Thirty HIV-positive participants (26 men and 4 women) with visceral adiposity were enrolled. The main outcome measure was change in visceral adipose tissue (VAT) on whole-body magnetic resonance imaging scan. Changes in whole-body subcutaneous adipose tissue and skeletal muscle, glucose metabolism, serum lipids, and quality of life were also assessed. Despite stable body weight, VAT decreased in evaluable subjects an average of 42% with rhGH 6 mg/d (n = 24; p <.001) and 15% with 4 mg every other day (n = 10; p <.01) after 12 weeks, with trends toward further decreases after an additional 12 weeks at each dose. Subcutaneous adipose tissue also decreased, but proportionately less and not significantly on the lower dose. Skeletal muscle increased. Body composition rebounded to or near baseline after the washout period. Effects on lipids were inconsistent. Total cholesterol levels fell on the higher dose only, whereas high-density lipoprotein cholesterol levels increased on the lower dose only, and there was no effect on triglyceride levels. Joint pain was the most common adverse event, and was reflected in subjective quality of life measurements as an increase in bodily pain. Insulin sensitivity fell, and 4 participants developed diabetes. Other adverse events included cancer of unknown relationship to treatment in 3 participants. Levels of distress decreased after 24 weeks on the higher dose. In conclusion, rhGH effectively reduces the excess visceral adipose tissue often associated with HIV fat redistribution/lipodystrophy. However, frequent adverse effects warrant controlled studies and careful patient monitoring, especially regarding glucose tolerance.

Incidence of AD may decline in the early 90s for men, later for women: The Cache County study

OBJECTIVES

To characterize the incidence of AD among the elderly population of Cache County, UT, noted for its longevity and high response rates; to explore sex differences; and to examine whether AD incidence plateaus or declines in extreme old age.

METHODS

Using a multistage screening process in 1998 and 1999, and re-examining 122 individuals who had been identified 3 years earlier as cognitively compromised but not demented, the authors found 185 individuals with incident dementia (123 with AD) among 3,308 participants who contributed 10,541 person-years of observation. Adjusting for nonresponse and screening sensitivity, the authors estimated the incidence of dementia and of AD for men and women in 3-year age intervals. Multivariate discrete time survival analysis was used to examine influences of age, sex, education, and genotype at APOE, as well as interactions of these factors.

RESULTS

The incidence of both dementia and AD increased almost exponentially until ages 85 to 90, but appeared to decline after age 93 for men and 97 for women. A statistical interaction between age and the presence of two APOE-epsilon 4 alleles indicated acceleration in onset of AD with this genotype; the interaction of age and one epsilon 4 suggested more modest acceleration. A statistical interaction of sex and age indicated greater incidence of AD in women than in men after age 85.

CONCLUSIONS

The incidence of AD in the Cache County population increased with advancing age, but then peaked and declined among the extremely old. The presence of APOE-epsilon 4 alleles accelerated onset of AD, but did not appreciably alter lifetime incidence apparent over a span of 100 years.

Body composition abnormalities in children with Prader-Willi syndrome and long-term effects of growth hormone therapy

Obesity and hypothalamic GH deficiency contribute in different ways to the disturbances of body composition in Prader-Willi syndrome (PWS); while both increase the fat compartment, the reduction of lean tissue mass has been attributed mainly to GH deficiency. Therefore, body composition measured by dual-energy X-ray absorptiometry was prospectively studied in 12 overweight children with PWS and weight for height (WfH) SDS >0 before and during 3.5 years of treatment with hGH (0.037 mg/kg/day) on average. In the long term, there is a net reduction of body fat from 3.1 to 1.2 SD, with a minimum at the end of the second year of treatment. WfH SDS correctly reflects body fat mass and its changes. The initial deficit of lean mass (-1.6 SD) is counteracted by GH only during the first year of therapy (increase to -1.25 SD). But in the long term, GH therapy does not further compensate for this deficit, when lean mass is corrected for its growth-related increase. In conclusion, exogenous GH changes the phenotype of children with PWS: fat mass becomes normal, but, at least in the setting studied, GH is not sufficient to normalize lean tissue mass.

Growth hormone and adipocyte function in obesity

In obesity, growth hormone (GH) secretion is impaired which is considered a consequence rather than a cause of obesity. GH regulates the expression of GH receptor and the synthesis of insulin-like growth factor I (IGF-I) in adipocytes. Although GH hyposecretion in obesity may decrease the generation of IGF-I in each adipocyte, increased amounts of IGF-I and GH-binding protein could be secreted from the excessively enlarged amounts of adipose tissue. This may contribute to the normal/high serum-IGF-I and high GH-binding protein levels in obesity. Hyperinsulinemia and increased GH receptor activity may also affect the GH-IGF-I axis. Favorable effects of GH treatment have been observed in obese children and adults. GH treatment decreases adiposity, reduces triglyceride accumulation by inhibiting lipoprotein lipase and enhances lipolysis both via increased hormone-sensitive lipase activity and via induction of beta adrenoreceptors. GH treatment also has a favorable effect on obesity-associated dyslipidemia, but the effects on insulin sensitivity have been conflicting.

Is there growth hormone deficiency in prader-willi Syndrome? Six arguments to support the presence of hypothalamic growth hormone deficiency in Prader-Willi syndrome

Prader-Labhart-Willi syndrome (PWS) is the most frequent form of syndromal obesity. Its main features are associated with hypothalamic dysfunction, which has not yet been comprehensively described. The aim of this review is to present arguments to define the presence of genuine growth hormone (GH) deficiency (GHD) in these patients. Decreasing growth velocity despite the onset of obesity, reduced lean body mass in the presence of adiposity, small hands and feet, relatively low insulin-like growth factor-I and low insulin levels, as well as the dramatic effect of GH treatment on growth, support the presence of hypothalamic GHD in PWS. Even though it might be difficult to ultimately prove GHD in PWS because of the obesity-induced counterregulation, the hormonal situation differs from that in simple obesity. The effects of long-term therapies with GH on body composition in these patients are summarized. GH therapy dramatically changes the phenotype of PWS in childhood: height and weight become normal and there is a sustained impact on the net loss of body fat. We conclude that GHD may account for several features of PWS.

Growth hormone: current and future therapeutic applications

The increased availability of growth hormone (GH) in the mid-1980s, as a result of advances in recombinant DNA techniques, has allowed research into the use of this hormone at physiological dosage, as replacement therapy for adults with GH deficiency (GHD) and at pharmacological dosages as a possible therapeutic agent, for a number of disease states. GHD adults have increased body fat and reduced muscle mass and consequently, reduced strength and exercise tolerance. In addition, they are osteopenic, have unfavourable cardiac risk factors and impaired quality of life. In these individuals, replacing GH reverses these anomalies, although it may not alter the reduced insulin-sensitivity. A proportion of adults with GHD perceive a dramatic improvement in their well-being, energy levels and mood following replacement. GH has protein and osteoanabolic, lipolytic and antinatriuretic properties. GH has been considered for the therapeutic treatment of frailty associated with ageing, osteoporosis, morbid obesity, cardiac failure, major thermal injury and various acute and chronic catabolic conditions. Initial small, uncontrolled studies for many of these clinical problems suggested a beneficial effect of GH, although, later placebo-controlled studies have not observed such dramatic effects. Furthermore, with a recent publication demonstrating an approximate 2-fold increase in mortality in critically ill patients receiving large doses of GH, the use of GH should remain in the realms of replacement therapy and research, until there are significant advances in our understanding.

Age-specific incidence rates of Alzheimer's disease: the Baltimore Longitudinal Study of Aging

OBJECTIVE

To estimate age-specific incidence rates of AD in the Baltimore Longitudinal Study of Aging (BLSA).

BACKGROUND

The BLSA is a volunteer cohort of normal subjects followed longitudinally with biennial evaluations at the Gerontology Research Center of the National Institute on Aging.

METHODS

Subjects are 1236 participants (802 men, 434 women) in the BLSA with longitudinal follow-up between January 1985 and May 1998. The average length of follow-up was 7.5 years, with participants evaluated every 2 years by physical, neurologic, and neuropsychological examinations. Using Diagnostic and Statistical Manual of Mental Disorders, 3rd ed., revised and National Institute of Neurological and Communicative Disorders and Stroke-Alzheimer's Disease and Related Disorders Association criteria, the authors diagnosed dementia and AD.

RESULTS

The authors diagnosed 155 cases of dementia, of which 114 (74%) were AD. Incidence rates of AD increased with age from an estimated 0.08% per year (95% CI 0.00 to 0.43) in the 60 to 65 age group to an estimated 6.48% per year (95% CI 5.01 to 8.38) in the 85+ age group for men and women combined. The doubling time of incidence rates was estimated to be approximately 4.4 years and the median time of conversion from mild cognitive impairment to diagnosis of AD was estimated to be 4.4 years. There was a trend for women to have higher incidence rates than men and for fewer years of education to be associated with higher incidence rates; however, these effects were not significant.

CONCLUSION

Incidence rates for AD in the BLSA are consistent with published rates in other studies. The longitudinally followed subjects of the BLSA offer a unique opportunity to prospectively investigate the antecedents of AD.

Medicinal strategies in the treatment of obesity

When prevention fails, medicinal treatment of obesity may become a necessity. Any strategic medicinal development must recognize that obesity is a chronic, stigmatized and costly disease that is increasing in prevalence. Because obesity can rarely be cured, treatment strategies are effective only as long as they are used, and combined therapy may be more effective than monotherapy. For a drug to have significant impact on body weight it must ultimately reduce energy intake, increase energy expenditure, or both. Currently approved drugs for long-term treatment of obesity include sibutramine, which inhibits food intake, and orlistat, which blocks fat digestion.