A review of the literature shows that the admission rates of new cases of schizophrenia vary with a factor of two to five in North American studies as well as in European studies. Furthermore, the tendency has been decreasing for the last 40–50 years in Europe. Eighteen studies specifically analyzing the development over the last 20 years are reviewed. The studies preponderantly show significant decreases most probably due to the reduction of the number of available psychiatric beds alongside the decentralization of psychiatry, and to decreasing virulence of schizophrenia. Alternatively, a diagnostic delay of schizophrenia can hardly explain the decrease.

Dietary fat intake in childhood may influence the risk for developing chronic diseases. The objective of the present study was to examine secular trends in the parameters of fat intake between 2000 and 2010 in a sample of German children and adolescents (n 808) participating in the Dortmund Nutritional and Anthropometric Longitudinally Designed (DONALD) Study. Dietary data from 4380 3 d weighed dietary records were analysed using repeated-measures regression to determine time trends in fat quantity, i.e. the intake of total fat, and in fat quality, i.e. the ratios of SFA, MUFA and PUFA. In young children (2–3 years) and in adolescents (13–18 years), total fat intake remained stable over time, but decreased by 0·08 % of total energy (%E) per year in 4–12-year-old children. In 2010, median fat intake was at the upper end of the recommendations. SFA intake decreased slightly in 2–3- and 4–12-year-old children by 0·09 and 0·05 %E per year, respectively. MUFA and PUFA intakes remained stable in all the age groups except in adolescents. Here, PUFA intake decreased initially, but increased between 2005 and 2010. In 2010, only between 3 and 18 % of the respective age groups had an intake of SFA or PUFA within the recommendations. In conclusion, fat quantity and quality did not change substantially between 2000 and 2010. Fat quality, in particular, needs to be improved, since a large percentage of our sample did not meet the recommended intakes for SFA and PUFA.

A study was made of the seasonal variation in all births, and births according to marital status, multiplicity and birth status (live and still) in Switzerland recorded between 1876 and 1990. To obtain seasonal variation in as pure as possible form, our analyses are based on rates. When comparing the seasonality in data sets showing markedly different levels, standardised indices were used. Assuming the length of pregnancies with twins to be about one month shorter than for pregnancies with singletons, lagged twinning rates were calculated but, in comparison with actual twinning rates, the general seasonal variation remained. Therefore, this study was based on actual twinning rates. A monotonic increase in the amplitude of the seasonal variation in general births was noted for the period 1876–1930, with strong seasonal variation holding for 1921–1980. After that, a marked decline in the amplitude can be observed. Seasonality of both all births and twin maternities showed very similar pattern for the periods 1876–1930 and 1969–1990, with maxima in the spring (March–May) and troughs in late autumn (October–December). Twin maternities showed a strong seasonality for the period 1876–1930, being about 20% higher in March than in October. The twinning rate in the period 1876–1930 was about 2.6 per thousand units higher than in the period 1969–90. For twin maternities there was also a stronger seasonal variation during the earlier period than during the later one. The pattern of the seasonal variation for extramarital births, showing a maximum in February (conceptions in May–June) and a minimum in August (conceptions in November–December) with a difference of no less than 24% was more marked than for the marital births. It seems likely that this seasonality of extra-marital maternities was due mainly to seasonal variation of coital rates and multiple ovulation in the early summer months coinciding with optima of light, temperature and food supply. A strong reduction in the rate of stillbirths (gestational age more than 29 weeks) was observed during the twentieth century. The stillbirth rate declined from about 40 per 1000 in the 1870s to fewer than 5 per 1000 in the 1980s. Irrespective of this strong decline in the stillbirth rate, the same seasonal rhythm was noticed throughout the period with high stillbirth rates among births around March and low rates during the summer and autumn. Twin Research (2000) 3, 189–201.

The extent to which the quality of dietary carbohydrates (CHO) changes throughout puberty is not known. We analysed trends in the quantity and quality of CHO intake among German adolescents by separately examining trends during puberty (pubertal trends) and trends in CHO intake from 1988 to 2007 (secular trends). Linear mixed-effects regression analyses were performed in 216 participants of the Dortmund Nutritional and Anthropometric Longitudinally Designed Study who had provided weighed 3 d dietary records at the onset of the pubertal growth spurt (defined by age at take-off) and over the subsequent 4 years. Over the course of puberty, CHO quality changed little: added sugar intake from beverages increased in girls (0·25 (se 0·12) % energy (% E)/year, P = 0·04) and added sugar intake from sweets decreased in both sexes (boys: − 0·22 (se 0·11) % E/year, P = 0·049; girls: − 0·20 (se 0·10) % E/year, P = 0·04). For both sexes, significant upward secular trends were observed for CHO (% E), glycaemic load (g/MJ) and added sugar intakes from sources other than sweets and soft drinks (% E), while absolute fibre intake (g/d) decreased (P ≤ 0·04). Concomitant increases in total added sugar intake (% E) and decreases in fibre and whole-grain densities (g/MJ) (P = 0·001–0·02) were confined to boys only. The quality of dietary CHO consumed by healthy German adolescents shows notable secular declines, but does not change markedly during puberty. Public health initiatives should be tailored to improve the overall quality of CHO nutrition.

In countries of the Mediterranean region, nuts have been consumed in moderate quantities since ancient times. Epidemiological studies show lower risk of cardiovascular diseases in populations with frequent nut consumption, independent from other dietary components. This article assesses nut consumption in Spain and other countries using different sources of data collected at the country, household or individual levels. The per capita consumption of nuts in Spain in 2001 was 7·9 g/person/d. The varieties most widely consumed are walnuts, almonds, hazelnuts and peanuts. Results of the eVe study estimate an average nut consumption in the Spanish population aged 25–60 years of 3·3 g/person/d. No significant statistical differences were observed between men and women. Consumption is higher in men aged between 35 and 44 years (4·5 g/d) and in women aged between 45 and 54 years (3·5 g/d). In the population of 2–24 years, according to the enKid study, nut consumption is estimated at 4·9±18·5 g/person per d. The age group with the highest consumption is teenagers between 14 and 17 years. The northeastern, northern and eastern regions of Spain show the highest consumption. According to FAO balance sheets, in 2001, Lebanon (16·5 kg/person peryear) and Greece (11·9 kg/person per year) were the countries in the Mediterranean region with the highest consumption of nuts, followed by Spain (7·3 kg/person per year), Israel and Italy.

The dizygotic twinning rate in Italy, adjusted for maternal age and parity, declined from 8.9/1000 in 1949-1953 to 6.0/1000 in 1978-81, but may have stabilized or recovered slightly in the early 1980s. The long decline was greatest in the oldest mothers, and the recent increase, if any, has been principally in first births and in women under 30. The monozygotic rate rose from 3.8/1000 in 1969-73 to 4.3/1000 in 1982-85, having been relatively stable prior to that period. No good explanation for these trends is apparent.

This paper examines aspects of the epidemiology of affective disorders in Scotland. Results from 3 investigations are described, each one indicative of a particular research approach (the use of national, case-register and direct-interview based data). In Part I of the paper secular trends in Scottish national and local (Edinburgh city) first admission rates of affective disorders, based upon ICD-9, are examined. The results, based upon the national data, show that during the last two decades the male admission rate declined by 29.4% and the female rate by 37.3%. However, the female rate has remained 1.8 to 2.2-fold that of the male rate throughout this period. Further investigation of these changes was undertaken after dividing the affective disorder category into either the “affective psychoses” or the “depressive neuroses”. Results revealed that whilst there was only a slight change in the Scottish national rate of affective psychoses, marked decreases in rates were revealed for the depressive neuroses for both sexes (males by 39.4% and females by 39.3%). Age-specific secular trends also demonstrated the extent to which the older age groups of both sexes experienced the highest rates of affective psychoses.

Results based upon first admissions for affective disorder to the Royal Edinburgh Hospital over the years 1976-1987 showed that the overall male rate had remained relatively unchanged, whilst that for females had declined by about 24%. Subsequent analysis showed that the rates for affective psychoses had declined over the 12 years to a level which for the females was close to the national rate but that the male rate for these conditions had remained (in 1985) at 70% above the Scottish national rate.

Part II of this paper presents results from two further studies concerned with investigating rates of affective disorder amongst women. The first of these was a general population survey of a random sample, the second a hospital study. Both studies were designed to be complementary, in that each was based upon samples of women living in the same geographical area of Edinburgh city. Results revealed that the hospital prevalence estimate for affective disorders was only about 1% of the community estimate, but over 5% of the community inception rate. Analyses examining the demographic correlates of affective disorders revealed the extent to which age and marital status differentially determined the ease with which women entered hospital care. Results revealed that being single and of older age was associated with an increased chance of receiving treatment for women with affective disorders.

Stillbirth rates of MZ and DZ twins in Japan gradually decreased during the period 1960–1967 and in 1974. The stillbirth rates of MZ and DZ twins were 0.270 and 0.224 in 1960, respectively, whereas the corresponding figures in 1974 were 0.135 and 0.099. The stillbirth rate was higher in MZ than DZ twins, in males than females, and in the second- than in the first-born. In both zygosities, the rates were higher in the first birth order than in the second, and then increased with birth order except in the sixth birth or more for MZ twins and for DZ twins born to mothers aged 35–39 years. The shorter the gestational age, the higher the stillbirth rate in both MZ and DZ twins, as expected. Mean gestational age was slightly shorter in MZ than in DZ twins. The decrease of the stillbirth rates can be explained partly by the reduction of twins with higher birth order, where high stillbirth rates of MZ and DZ twins are seen, and the reduction of older mothers.