Seasonal variation in anorexia nervosa? Some preliminary findings from a neglected area of research

Abstract

A review of the literature on normal development and on psychiatric disorders related to seasonal variation, suggests that this phenomenon is probable to occur in anorexia nervosa. A search of the available literature is entirely negative with respect to seasonal variation in anorexia nervosa. Preliminary analysis suggests the existence of a season of onset, a season of birth, and also oi a season of admission in Danish female anorexia nervosa patients. A formally correct analysis for seasonal variation supports the existence of a season of onset in a selected sample, maximum is in May, amplitude 50%. A season of birth is found in an unselected nationwide sample of patients aged 15 years or older at first psychiatric admission for anorexia nervosa. Maximum late in April, amplitude 40% in the period 1963–1968. Season of admission could not be modelled as a sine wave, but the data suggested a pulse structure (a minimum in one month, followed by a maximum in the next month). Two annual pulses: December/January and July/August. Peak of onset is at a time of the year with maximum increase in height, and peak of other psychiatric conditions. Pattern of birth is similar to that reported for schizophrenia and mania. Replications of this preliminary study should be done in larger countries, at different latitudes and continents. Geophysical, demographic, and climatological variables should be controlled.

Seasonal variation of BMI at admission in German adolescents with anorexia nervosa

“…However, our data do not support this hypothesis and indicate that seasonal variation of BMI in AN is most likely more complex. This is in line with Nielsen[ 29 ], who found, for example, two annual admission peaks for AN in winter and summer. Several other biological, behavioral, cognitive and even structural factors such as growth, changes in physical activity or body dissatisfaction, depressiveness, or waiting time, might confound an overly simplified association of season with BMI, as these factors themselves might be subject to seasonal variation.…”

Seasonal variation of BMI at admission in German adolescents with anorexia nervosa

“…However, our data do not support this hypothesis and indicate that seasonal variation of BMI in AN is most likely more complex. This is in line with Nielsen[ 29 ], who found, for example, two annual admission peaks for AN in winter and summer. Several other biological, behavioral, cognitive and even structural factors such as growth, changes in physical activity or body dissatisfaction, depressiveness, or waiting time, might confound an overly simplified association of season with BMI, as these factors themselves might be subject to seasonal variation.…”

Is season of birth related to disordered eating and personality in women with eating disorders?

“…By ignoring missing birth date data, most studies [e.g., (1, 2, 8)] did not account for exactness of birth dates. We excluded participants missing these data while employing a sample large enough to make meaningful comparisons.…”

“…In some studies, eating disorder samples were compared to the general population (1, 5, 6). Often control participants’ birth years only partly overlapped with affected participants’ (3, 5, 6).…”

“…As birth rates differ across time, control and eating disorders groups should assess the same birth years. Differing diagnostic systems and sample selection (1, 3, 5) have made comparative interpretations difficult. We clearly defined diagnostic criteria and used experienced assessors.…”

Prevalence of eating disorders in Norwegian general hospitals 1990-1994: Admissions per year and seasonality

“…Seasonality has been reported with AN (Fornari et al, 1989;Hardin et al, 1991;Brewerton et al, 1994), but rarely in relation to hospitalization. Nielsen (1992) reported that preliminary analyses suggest the existence of season of onset, a season of birth, and a season of first admission in Danish female AN patients. Rezaul, Persaud, Takei, and Treasure (1996) reported a statistically significant season of birth in an unselected nationwide sample of 1,939 eating disorder patients, but they did not look into season of admission.…”

Seasonal variation of BMI at admission in German adolescents with anorexia nervosa

“…However, our data do not support this hypothesis and indicate that seasonal variation of BMI in AN is most likely more complex. This is in line with Nielsen[ 29 ], who found, for example, two annual admission peaks for AN in winter and summer. Several other biological, behavioral, cognitive and even structural factors such as growth, changes in physical activity or body dissatisfaction, depressiveness, or waiting time, might confound an overly simplified association of season with BMI, as these factors themselves might be subject to seasonal variation.…”

Is season of birth related to disordered eating and personality in women with eating disorders?

“…By ignoring missing birth date data, most studies [e.g., (1, 2, 8)] did not account for exactness of birth dates. We excluded participants missing these data while employing a sample large enough to make meaningful comparisons.…”

“…In some studies, eating disorder samples were compared to the general population (1, 5, 6). Often control participants’ birth years only partly overlapped with affected participants’ (3, 5, 6).…”

“…As birth rates differ across time, control and eating disorders groups should assess the same birth years. Differing diagnostic systems and sample selection (1, 3, 5) have made comparative interpretations difficult. We clearly defined diagnostic criteria and used experienced assessors.…”

Prevalence of eating disorders in Norwegian general hospitals 1990-1994: Admissions per year and seasonality

“…Seasonality has been reported with AN (Fornari et al, 1989;Hardin et al, 1991;Brewerton et al, 1994), but rarely in relation to hospitalization. Nielsen (1992) reported that preliminary analyses suggest the existence of season of onset, a season of birth, and a season of first admission in Danish female AN patients. Rezaul, Persaud, Takei, and Treasure (1996) reported a statistically significant season of birth in an unselected nationwide sample of 1,939 eating disorder patients, but they did not look into season of admission.…”

Seasonal variation of BMI at admission in German adolescents with anorexia nervosa

“…However, our data do not support this hypothesis and indicate that seasonal variation of BMI in AN is most likely more complex. This is in line with Nielsen[ 29 ], who found, for example, two annual admission peaks for AN in winter and summer. Several other biological, behavioral, cognitive and even structural factors such as growth, changes in physical activity or body dissatisfaction, depressiveness, or waiting time, might confound an overly simplified association of season with BMI, as these factors themselves might be subject to seasonal variation.…”

Is season of birth related to disordered eating and personality in women with eating disorders?

“…By ignoring missing birth date data, most studies [e.g., (1, 2, 8)] did not account for exactness of birth dates. We excluded participants missing these data while employing a sample large enough to make meaningful comparisons.…”

“…In some studies, eating disorder samples were compared to the general population (1, 5, 6). Often control participants’ birth years only partly overlapped with affected participants’ (3, 5, 6).…”

“…As birth rates differ across time, control and eating disorders groups should assess the same birth years. Differing diagnostic systems and sample selection (1, 3, 5) have made comparative interpretations difficult. We clearly defined diagnostic criteria and used experienced assessors.…”

Prevalence of eating disorders in Norwegian general hospitals 1990-1994: Admissions per year and seasonality

“…Seasonality has been reported with AN (Fornari et al, 1989;Hardin et al, 1991;Brewerton et al, 1994), but rarely in relation to hospitalization. Nielsen (1992) reported that preliminary analyses suggest the existence of season of onset, a season of birth, and a season of first admission in Danish female AN patients. Rezaul, Persaud, Takei, and Treasure (1996) reported a statistically significant season of birth in an unselected nationwide sample of 1,939 eating disorder patients, but they did not look into season of admission.…”