Volume 166 Issue 8

The Hobart Salt Study 1995: few meet national sodium intake target Trevor C Beard, David R Woodward, Peter J Ball, Helen Hornsby, Richard J von Witt and Terence Dwyer MJA 1997; 166: 404 For editorial comment see Beilin Readers may print a single copy for personal use. No further reproduction or distribution of the articles should proceed without the permission of the publisher. For permission, contact the Australasian Medical Publishing Company Journalists are welcome to write news stories based on what they read here, but should acknowledge their source as "an article published on the Internet by The Medical Journal of Australia <http://www.mja.com.au/>". Abstract - Introduction - Methods - Statistical analysis - Results - Sodium and potassium excretion - Discretionary use of salt - Discussion - Public health implications - Conclusion - Acknowledgements - References - Authors' details - - ©MJA1997 Abstract Objective: To estimate 24-hour sodium and potassium excretion in an urban Australian population. Design and setting: Cross-sectional survey of an urban population in Hobart, Tasmania, in 1995. Participants: Systematic sample (87 men, 107 women) from the Commonwealth Electoral Roll of people aged 18-70 years on 30 June 1995 whose residential address was within 10 km of the Hobart General Post Office. Main outcome measure: Conformity with the national target for sodium intake for the year 2000 of ≤100 mmol/day. Results: The target was met by 6% of men and 36% of women. This difference between the sexes was significant ( P < 0.001), while differences between age groups and socioeconomic levels were not significant. Conclusion: Our findings confirm the low level of conformity with the national sodium target reported by the handful of Australian studies over the past decade. Given the major community costs associated with hypertension, our results highlight the need for effective and properly monitored action to reduce sodium intakes. MJA 1997; 166: 404-407 Introduction Many health problems are associated with the current sodium intake of people in Western societies.1 In 1988, an Australian target for a lower sodium intake was set for the express purpose of reducing the prevalence of hypertension.2 Although other factors, such as excess body weight, inadequate exercise, excess alcohol, low dietary potassium and "psychological influences", may contribute to hypertension,3 Australia's national target for sodium intake (≤100 mmol/day)2 is accepted internationally.4-6 Further, it is supported by the discovery that the usual human salt intake in Western diets induces hypertension in chimpanzees, and that this is reversed when they return to their natural diet.7 The effect of low dietary potassium on health has received less attention, but there is good evidence that potassium intake should at least equal sodium intake in molar units.8,9 Potassium predominates in unsalted foods because it is the major intracellular cation in the living tissues of both plants and animals. Thus, virtually all the natural foods available to mammals have a molar sodium to potassium ratio of less than 1.0. The human body must have evolved on this dietary ratio; its inversion is recent in phylogenetic terms, unnecessary and probably unsafe.8,9 Published data on current intakes of sodium and potassium among Australians are very few, and usually based on small samples10-12 We report electrolyte excretion data obtained from 194 Hobart residents for a behavioural study in 1995. Our estimates are based on 24-hour excretion of these electrolytes in the urine (widely accepted as the preferred method of assessment of intake).13,14 Methods People aged 18-70 years on 30 June 1995 and residing within 10 km of the Hobart General Post Office were selected from the Commonwealth Electoral Roll (revised to February 1995) as follows. Every 500th person on the roll was selected for contact or, if ineligible, replaced by the next eligible person. A letter inviting participation was mailed to each person, outlining the study (including the need to attend for interview and to provide a 24-hour urine sample) and enclosing a reply-paid envelope. Those failing to reply were sent a second letter two weeks later, followed, if necessary, by a telephone call within a further 10 days. Unpredictable variability in sodium excretion (a confounder in the behavioural study) was reduced by excluding volunteers with serious intercurrent illness, pregnancy, breast-feeding or use of potassium supplements, diuretics or other drugs likely to affect sodium excretion. We estimated socioeconomic status by the postcode of the participant's address, using the Index of Relative Socioeconomic Disadvantage (IRSD);15 data for specific postcodes were supplied by the Australian Bureau of Statistics. Suburbs whose postcodes had an IRSD ≤ 1000 (the national mean score) were classified as "lower socio economic status", and those with an IRSD ≥ 1000 as "higher socioeconomic status". Two subjects listed a GPO box address and were not assigned a socio economic status rating. At interview, we collected demographic and anthropometric data and a short medical history. Participants completed a food-frequency questionnaire and answered behavioural and cognitive questions, which will be reported elsewhere. Each participant received detailed verbal and written instructions on how to make a complete 24-hour collection of urine; all were asked to collect urine on weekdays, and women of reproductive age were asked to avoid collection during the premenstrual week, when sodium retention may occur.16 Participants collected urine in 2 L plastic containers containing 20 mL of 6 molar hydrochloric acid and returned them promptly. Urine volume was estimated by weighing. For 82 of the 194 samples the estimated volume was adjusted to 24 hours because of longer or shorter actual collection times; the maximum adjustment was 175 minutes over the 24 hours (12.2%), and only five adjustments exceeded 5%. The samples, identified only by code numbers, were diluted with neutral pH buffer and analysed for sodium and potassium by ion-selective electrodes on a Kodak Ektachem 750 XRC analyser (Johnson & Johnson Clinical Diagnostics, Rochester, NY, USA) and, for creatinine, by the Ektachem method also. Laboratory results were sent to those participants who requested them. A duplicate of every tenth sample was sent for analysis under a different code number for quality assurance. We calculated imprecision of laboratory measurements from the differences between results for duplicate samples using the formula published for the Intersalt study.17 The coefficients of variation for laboratory imprecision were 0.6% for sodium, 1.1% for potassium and 5.4% for creatinine. The protocol was approved by the University of Tasmania Committee on Ethical Aspects of Human Experimentation, and all subjects gave written informed consent. Statistical analysis We used SPSS18 to analyse the data; P< 0.05 was used as the criterion of statistical significance. Differences between sexes, age groups and socioeconomic status levels were assessed by t tests (for mean sodium and potassium excretion rates) and by chi-squared tests (for compliance with targets for sodium and sodium to potassium ratio). Results Of 619 individuals originally selected, 167 (27%) were uncontactable despite active follow-up, 80 (13%) were ineligible because they had moved out of the target area, 151 (24%) declined to take part, 18 (3%) were eliminated by our exclusion criteria (nine for medications, five for illness, and four for pregnancy or lactation), and nine participated incompletely. The remaining 194 (31% of the initial sample, or 52% of those known to be eligible) were interviewed and provided a 24-hour urine collection. Box 1 (below) compares sociodemographic characteristics for these 194 participants with those of the other 425 people originally selected. The two groups had a similar sex distribution, but participants were significantly older and had higher socioeconomic status. For participants, the sex ratio was similar in both age divisions (43% men in the 18-44 years group and 46% men in the 45-70 years group), and in both socioeconomic groups (47% and 44% men in the lower and higher socioeconomic status groups, respectively). While we do not have birthplace data for the non-participants, most participants were born in Australia (83%) or in the United Kingdom or Ireland (12%). Sodium and potassium excretion Twenty-four-hour sodium excretion was greater in men (range, 39-337 mmol) than in women (26-241 mmol), and the mean sodium intake (as reflected by this excretion rate) was 52 mmol higher in men than in women, a highly significant difference (P< 0.001). Only 6% of men, compared with 36% of women, met the Australian national target (≤ 100 mmol/day), represented by the vertical line in the Figure, and this difference was also significant at P< 0.001. Differences between age groups and socioeconomic status groups were not significant at the P< 0.05 level (Box 2, below). The mean potassium intake in men was 9 mmol higher than in women (P = 0.03), but differences between age groups and socioeconomic status groups were not significant (Box 2, above). Only 5% of men and 19% of women met the recommendation8,9 that the sodium to potassium ratio should not exceed 1.0 (diagonal line in the Figure); this sex difference was significant (P = 0.002). Differences were not statistically significant between younger and older participants (P = 0.33), and were on the margin of significance for socioeconomic status levels (P = 0.05). Discretionary use of salt Most of our 194 participants claimed that they never or rarely added salt at the table (51% of men and 73% of women), and that they never or rarely cooked with salt (54% of men and 61% of women). Compliers and non-compliers with the sodium target gave similar answers about the use of salt: 66% of compliers and 62% of non-compliers rarely or never added salt at the table, and 57% of compliers and 58% of non-compliers rarely or never cooked with salt. Discussion Despite our relatively low response rate, Box 1 shows that our participants had a similar sex ratio to that of a systematic sample from the Hobart electoral roll, and we found that sex differences in electrolyte excretion were significant. Although our sample was biased in terms of age and socioeconomic status, the effect of age and socioeconomic status on electrolyte excretion in the participants barely reached significance (Box 2), and hence these biases are unlikely to have influenced our findings. If the participants were unrepresentative in some other way -- more health-conscious, for example -- our data could underestimate sodium excretion and overestimate compliance with the sodium target. It is difficult to be certain of the completeness of 24-hour urine collections. Para-aminobenzoic acid has been used as a marker in overseas studies,19 but is not approved for use with healthy volunteers in Australia. Creatinine excretion is a customary indicator of completeness, but no standard cut-off points exist.19 As both undercollection and overcollection could have affected our results, we repeated the t-test analyses of Box 2 after excluding subjects whose creatinine outputs were in the lowest and highest 2.5% for men and women. For both sodium and potassium the changes in means and standard deviations were negligible, indicating no serious problem with outliers. Moreover, the range of excretion rates of each electrolyte in each sex remained unaltered. Accuracy and imprecision of assays are also important determinants of data quality. As reported in our Methods, duplicate assays indicated acceptable imprecision -- the laboratory is a participant in the Royal College of Pathologists of Australasia-Australian Association of Clinical Biochemists Quality Assurance Scheme and is accredited by the National Association of Testing Authorities. Few other Australian studies have been reported. In one, estimates based on food-frequency questionnaires were somewhat lower than ours,12 but urinary excretion is considered a more valid indicator of intakes.13,14 A Hobart study in 1989, with a similar protocol for sample selection and urine collection,10 found mean sodium and potassium excretion rates in men of 160 mmol/day and 77 mmol/day, respectively, compared with 124 mmol/day and 66 mmol/day in women. In Sydney, in 1992, Notowidjojo and Truswell11 found mean sodium and potassium excretion rates of 164 mmol/day and 74 mmol/day in men and 133 mmol/day and 66 mmol/day in women. These two studies support our conclusion that average intakes in Australia -- especially among men -- are substantially above the national target. Public health implications Meta-analysis by Law et al. indicates that a 50 mmol decrease in community sodium intake could reduce mortality from heart disease by 16% and from stroke by 22%.20 The annual cost to Australia of heart disease, stroke and hypertension was recently estimated at $1198 million, $666 million and $546 million, respectively.21 If a lower salt intake reduced prevalence as much as it reduced mortality, the saving from 16% less heart disease and 22% less stroke and hypertension would be $458 million annually, with added savings from reduced prevalence of other conditions.1 In the United Kingdom the complete elimination of table salt and cooking salt would reduce mean sodium intake by only about 15%.22 This figure might be even lower in Australia, as this and other studies show that most people already avoid adding salt to their food.23,24 The main source of dietary sodium -- at least 75% of the total -- is processed foods, and a major reduction depends on changing their composition.21 Government initiatives have been limited to recommending a lower salt content in processed foods,25 setting a national target for sodium intake of ≤100 mmol/day,2 and publishing the dietary guideline Choose low salt foods and use salt sparingly.26 Food manufacturers have made some commendable initiatives, but they depend on consumer demand, and little has been done to inform the public about the national target for sodium intake. Although some low-salt processed foods are available and labelled in accordance with the food regulations, shoppers receive little specific advice or encouragement to reduce their sodium intake by choosing them. Conclusion By setting a national sodium-intake target, Australian health authorities have accepted that excessive dietary sodium is an important health issue, with significant morbidity, mortality and economic costs. Our results indicate the need for an active campaign to promote and monitor the nation's sodium target effectively. Acknowledgements This study was carried out with an educational grant from the National Heart Foundation of Australia, and financial assistance towards the purchase of computer equipment was received from Sizzler Restaurants and from Salt Skip Incorporated. We are indebted to Leigh Blizzard, statistician at the Menzies Centre, for statistical advice. References Antonios TFT, MacGregor GA. Deleterious effects of salt intake other than effects on blood pressure. Clin Exp Pharmacol Physiol 1995; 22: 180-184. Health Targets and Implementation (Health For All) Committee. Health for all Australians. Canberra: AGPS, 1988: 38. WHO/ISH Statement Committee. Prevention of hypertension and associated cardiovascular disease: a 1995 statement. Clin Exper Hypertension 1996; 18: 581-593. National Research Council. Committee on diet and health. Implications for reducing chronic disease risk. Washington DC: National Academy Press, 1989: 16-17. World Health Organization. Diet, nutrition, and the prevention of chronic diseases. WHO Technical Report No. 797. Geneva: WHO, 1990: 61. Committee on Medical Aspects of Food Policy. Nutritional aspects of cardiovascular disease. Department of Health and Social Security. Report on health and social subjects No. 46. London: HMSO, 1994: 138. Denton D, Weisinger R, Mundy NI, et al. The effect of increased salt intake on blood pressure of chimpanzees. Nature Med 1995; 1: 1009-1016. Truswell AS. Potassium. In: Truswell AS, Dreosti IE, English RM, et al., editors. Recommended nutrient intakes: Australian papers. Sydney: Australian Professional Publications, 1990: 191-198. Stamler J, Rose G, Stamler R, et al. Intersalt study findings: public health and medical care implications. Hypertension 1989; 14: 570-577. Beard TC, Eickhoff R, Mejglo ZA, et al. Population-based survey of human sodium and potassium excretion. Clin Exp Pharmacol Physiol 1992; 19: 327-330. Notowidjojo L, Truswell AS. Urinary sodium and potassium in a sample of healthy adults in Sydney, Australia. Asia Pacific J Clin Nutr 1993; 2: 25-33. Baghurst KI, Crawford D, Worsley A, et al. The Victorian nutrition survey: a profile of the energy, macronutrient and sodium intakes of the population. Community Health Studies 1988; 12: 42-54. Caggiula AW, Wing RR, Nowalk MP, et al. The measurement of sodium and potassium intake. Am J Clin Nutr 1985; 42: 391-398. Hunter D. Biochemical indicators of dietary intake. In: Willett W, editor. Nutritional epidemiology. New York: Oxford University Press, 1990: 143-216. Australian Bureau of Statistics. Socio-economic indexes for areas. Canberra: ABS, 1990. MacGregor GA, Markandu ND, Roulston JE, et al. Is idiopathic oedema idiopathic? Lancet 1979; 1: 397-400. Intersalt Cooperative Research Group. Intersalt: an international study of electrolyte excretion and blood pressure. Results for 24 hour urinary sodium and potassium excretion. BMJ 1988; 297: 319-328. SPSS for Windows, release 6.1 [computer program]. Chicago: SPSS Inc, 1994. Bingham SA, Cummings JH. The use of creatinine output as a check on the completeness of 24-hour urine collections. Hum Nutr Clin Nutr 1985; 39C: 343-353. Law MR, Frost CD, Wald MJ. By how much does dietary salt lower blood pressure? III. Analysis of data from trials of salt reduction. BMJ 1991; 302: 819-823. National Heart Foundation of Australia. Heart and stroke facts report. Canberra: The Foundation, 1995. James WPT, Ralph A, Sanchez-Castillo CP. The dominance of salt in manufactured food in the sodium intake of affluent societies. Lancet 1987; 1: 426-429. Bennett SA, Magnus P. Trends in cardiovascular risk factors in Australia. Med J Aust 1994; 161: 519-527. Thomson A, Rundle S, Singh BB, et al. Regional differences in cardiovascular risk factor prevalence in Tasmania: are they consistent with the increased cardiovascular mortality? Aust N Z J Med 1995; 25: 290-296. National Health and Medical Research Council. Report of the working party on sodium in the Australian diet. Canberra: AGPS, 1984: 4. National Health and Medical Research Council. Dietary guidelines for Australians. Canberra: AGPS, 1992: 70-83. (Received 24 Jun, accepted 4 Nov, 1996) Authors' details Menzies Centre for Population Health Research, University of Tasmania, Hobart, TAS. Trevor C Beard, OBE, MB BChir, MPH, Senior Research Fellow; Helen Hornsby, BA(Hons), Research Assistant; Terence Dwyer, MD, MPH, Director. Division of Biochemistry, University of Tasmania, Hobart, TAS. David R Woodward, PhD, Senior Lecturer. Department of Psychology, University of Tasmania, Hobart, TAS. Peter J Ball, BSc, MA, Senior Lecturer. Department of Clinical Chemistry, Royal Hobart Hospital, Hobart, TAS. Richard J von Witt, FRCPath, FRCPA, Director. Reprints: Dr T C Beard, Menzies Centre for Population Health Research, 17 Liverpool Street, Hobart, TAS 7000. ©MJA 1997 <URL: http://www.mja.com.au/> © 1997 Medical Journal of Australia.

Trevor C Beard · David R Woodward · Peter J Ball · Helen Hornsby · Terence Dwyer

Psychosocial disorders in young people: on the agenda but not on the mend Richard Eckersley Resolving psychosocial problems among young Australians will not be quick or easy and requires greater commitment from all sectors of the community Readers may print a single copy for personal use. No further reproduction or distribution of the articles should proceed without the permission of the publisher. For permission, contact the Australasian Medical Publishing Company Journalists are welcome to write news stories based on what they read here, but should acknowledge their source as "an article published on the Internet by The Medical Journal of Australia <http://www.mja.com.au/>". - - ©MJA1997 Psychosocial problems have featured prominently in the news and on political agendas in Australia in the past year. In the wake of the Port Arthur (Tasmania) massacre, governments tightened gun laws1 and acted on portrayals of violence in the electronic media.2 The Federal Government more than doubled funding for its National Youth Suicide Strategy, to $32 million over four years.3 The Victorian Government seemed poised on the brink of major drug law reform, then retreated; recently, it established a Youth Suicide Prevention Task Force and launched a new drug strategy.4-6 However, if we, as a society, really want to get to the heart of these problems, we will have to change fundamental aspects of our society and culture. Despite many years of political action, it is arguable that none of these issues has been adequately addressed, as the developments of the past year make clear. We are still losing the war against drugs. Crime remains a serious social problem. The epidemic of youth suicide continues. In 1950, the (age-adjusted) suicide rate for males aged 15-24 was 6.9 per 100 000 and, in 1995, 24.8 per 100 000; among females in this age group, the suicide rate in 1950 was 2.2 and, in 1995, 6.2 (Jerry Moller, Assistant Director, National Injury Surveillance Unit, Australian Institute of Health and Welfare, Adelaide, SA, 1996, personal communication) (Figure). These trends occurred, even though fewer suicide attempts today are fatal, par ticularly those involving poisoning.7 This is the method favoured by females,8 who attempt suicide at least as often as males.9-11 Although suicide is an uncommon event, new research is revealing the extent to which it is the tip of the iceberg of psychological distress and disturbance among young people. The research shows that this distress is not an aberrant personal response to life; nor is it confined to marginalised or dis advantaged young people (see Box). A similar situation exists in other Western nations. An international review of time trends in psychosocial disorders in young people concludes that there has been a "surprising and troubling" rise in these disorders since World War II in nearly all developed countries. The disorders include crime, drug abuse, depression, suicidal behaviour and suicide (only with eating disorders do the authors say the evidence for a rise in prevalence is inconclusive).13 This review says that, to a large extent, finding causal explanations of the increases "remains a project for the future"; it acknowledges causes could differ for different disorders, and even for the same disorder at different periods. However, it rejects several popular explanations for the trends, such as social disadvantage and inequality and unemployment (although these can be associated with disorder at an individual level). More likely explanations are: family conflict and breakup; increased expectations; and changes in adolescent transitions (in particular, the emergence of a youth culture that isolates young people from adults and increases peergroup influence; more tension between dependence and autonomy; and breakdowns in cohabiting relationships among young people).13 In assessing threats to the well-being of young people, the final report of a 10-year study in the United States says that: "Altogether, nearly half of American adolescents are at high or moderate risk of seriously damaging their life chances. The damage may be near-term and vivid, or it may be delayed, like a time bomb set in youth."14 The report notes that social and technological changes this century -- including more divorces and single-parent families, the erosion of neighbourhood networks, greater media and peer influence, and a lack of jobs -- mean that adolescents could lack "two crucial prerequisites" for healthy growth and development: "a close relationship with a dependable adult and the perception of meaningful opportunities in mainstream society."14 The situation may also reflect a growing failure of mod ern Western culture to provide an adequate framework of hope, moral values, and a sense of belonging and meaning in our lives, so weakening social cohesion and personal re silience.15-17 In investing so much meaning in the individual "self", we have left it dangerously exposed and isolated, because we have weakened the enduring personal, social and spiritual relationships that give deeper meaning and purpose to our lives. These broader sociocultural perspectives suggest that, while tragedies such as suicide arise from intensely personal circumstances, they also represent the extreme end of a spectrum of responses by many young people to modern life, ranging through degrees of depression, drug abuse, delinquency and suicidal ideation to a pervasive sense of alienation, disillusionment and demoralisation. Surveys of youth attitudes suggest that many young people are mistrustful, cynical and fatalistic; wary of commitment; outwardly confident but inwardly insecure; and alienated and disconnected from society.17,18 Young people believe that life should be fast-moving and fun; that they have to fend for themselves; that lifestyle options should be kept open; that governments are incapable of solving society's problems; and that they themselves are powerless to change social conditions. Linked to these attitudes is a widespread pessimism about the future of the nation and the world. A recent study found that more than half of a representative sample of 800 Australians aged 15 to 24 thought the twenty-first century was more likely to be a time of crisis and trouble than one of peace and prosperity.18,19 Only a third thought Australia's quality of life would be better in 2010 than it is now, while a third thought it would be worse. Pessimism increased with age. When it comes to their own lives, most young people are optimistic, but recent research suggests that even this personal optimism crumbles under the pressures young people face as they grow up and make their own way in the world.9,20 One study found that that at 15 youth were optimistic and positive, but by 25 many had become disillusioned and rudderless: "Youth seem unusually apathetic about the future. They are not negligent or ignorant of the challenges; they just feel powerless to do anything about it. It is a sense of being disenfranchised and disengaged, awaiting the outcome of events rather than anticipating a role in them."20 A recent international survey conducted by a consortium of advertising agencies identified a teen generation characterised by four moods -- alienated, cynical, experimental and savvy (Joanne Turner, MojoPartners, Sydney, personal communication). The survey found that Australian teens were not excited about much in life; that they expressed a lack of direction; and that they were uncertain and apprehensive about the future. Suicidal ideation and behaviour in young people is associated with factors such as hopelessness and feelings that they have little influence over their environment (i.e., that there is an external locus of control).10,21 More broadly, hope has recently been described as "a pervasive and significant correlate of health and disorder".22 Psychological well-being is also associated with feelings that life has meaning, with positive meaning being related to strong religious beliefs, values that transcend the self, membership in groups, dedication to a cause and clear life goals.23 We need to pay close attention to the way in which the broad sociocultural features of our society could be contributing to a lack of meaning and a lack of hopefulness, and hence to psychosocial problems, among young people. References Office of the Prime Minister. Media release and transcript of press conference [on guns] by the Prime Minister, the Hon John Howard. Canberra: 10 May 1996. Media release by the Federal Minister for Communications and the Arts, Senator The Hon. Richard Alston. Government to tighten controls on media violence. Canberra: Office of the Federal Minister for Communications and the Arts, 9 July 1996. Update on national youth suicide prevention programs. Canberra: Commonwealth Department of Health and Family Services. 13 March 1997. Drug laws fall short: Pennington. The Age (Melbourne), 12 June 1996: 1. Press release. Premier convenes suicide prevention taskforce. Melbourne: Office of the Premier of Victoria and the Minister for Health. 29 January 1997. "Vic acts on teen drugs." The Canberra Times , 8 January 1997: 12. Harrison J, Moller J. Learning from experience: towards prevention. In, Selby H, editor. The inquest handbook. Sydney: Federation Press (in press). Harrison J, Moller J, Dolinis J. Suicide in Australia: past trends and current patterns. Australian Injury Prevention Bulletin, Issue 5. Adelaide: National Injury Surveillance Unit, Australian Institute of Health and Welfare, February 1994. Zubrick SR, Silburn SR, Garton A, et al. Western Australian child health survey: developing health and well-being in the nineties. Perth: Australian Bureau of Statistics and the Institute for Child Health Research, 1995. Allison S, Pearce C, Martin G, et al. Parental influence, pessimism and adolescent suicidality. Arch Suicide Res 1996; 1: 229-242. Schweitzer R, Klayich M, McLean J. Suicidal ideation and behaviours among university students. Aust N Z J Psychiatry 1995; 29: 473-479. Rickwood D, d'Espaignet E. Psychological distress among older adolescents and young adults in Australia. Aust N Z J Public Health 1996; 20: 83-86 . Rutter M, Smith DJ, editors. Psychosocial disorders in young people -- time trends and their causes. Chichester: John Wiley and Sons, for Academia Europaea 1995: 782-808. Carnegie Council on Adolescent Development. Great transitions -- preparing adolescents for a new century. Concluding report. New York: Carnegie Corporation of New York, 1995: 10. Eckersley R. Youth and the challenge to change. Melbourne: Australian Commission for the Future, 1992. Eckersley R. Failing a generation: the impact of culture on the health and well-being of youth. J Paediatr Child Health 1993; 29 Suppl 1: S16-S19. Eckersley R. Values and visions: youth and the failure of modern western culture. Youth Studies Australia 1995; 14 (1): 13-21. Australian Science, Technology and Engineering Council (ASTEC). Having our say about the future -- young people's dreams and expectations of Australia in 2010 and the role of science and technology. Report of the ASTEC Youth Partnership Study 1996. Canberra: AGPS, 1996. First text citation to: Discussion paper, Appendix B. Eckersley R. Young people's perceptions of the future: what they mean and why they matter. pp 60-65. Second text citation to report as a whole. Eckersley R. Dreams and expectations: young people's views of the future. Youth Studies Australia 1996; 15 (3): 11-17 . A brief description of the youth futures program of the Australian Commission for the Future. Melbourne: Australian Commission for the Future, 1996. Pearce C, Martin G. Locus of control as an indicator of risk for suicidal behaviour among adolescents. Acta Psychiatr Scand 1993; 88: 409-414. Nunn KP. Personal hopefulness: a conceptual review of the relevance of the perceived future to psychiatry. Br J Med Psychol 1996; 69: 227-245. Zika S, Chamberlain K. The relation between meaning in life and psychological well-being. Br J Psychol 1992; 83: 133-145. Authors' details 23 Goble Street, Hughes, ACT. Richard Eckersley, BSc(Hons), MScSoc, Strategic Analyst and Science Writer. No reprints will be available from the author. Correspondence: Mr Richard Eckersley, 23 Goble Street, Hughes, ACT 2605. 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Richard Eckersley