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PubMed1995

Effects of season on electro-oculographic ratio in winter seasonal affective disorder.

Low electro-oculographic (EOG) ratios have been reported in patients with seasonal affective disorder (SAD) during the winter. This study evaluated the effects of the changing seasons on EOG ratios in SAD patients. Sixteen outpatients with SAD and 16 age-, sex-, and medication-matched normal volunteers had EOG testing during the winter and again during the summer. There was a significant season x group interaction in EOG ratios, with normal subjects showing higher ratios in winter than in summer--a seasonal variation not observed in SAD patients. SAD patients may have a subsensitivity to environmental light that leads them to experience symptoms during the winter.

Adult↗
PubMed1996

Seasonal alteration in taste detection and recognition threshold in seasonal affective disorder: the proximate source of carbohydrate craving.

Increased appetite with associated carbohydrate craving are core symptoms of seasonal affective disorder (SAD) and have been attributed to decreased central serotonergic function. The proximate mechanisms for centrally mediated selective macronutrient consumption are unknown. We questioned whether seasonal alterations in taste sensation could serve as a mediator of dietary intake, as implied by the term 'craving'. Specifically, individuals who were seasonally depressed and reported carbohydrate craving would be more sensitive to gustatory cues associated with the presence of carbohydrate than nondepressed subjects. Taste detection and recognition thresholds for the four primary gustatory sensations--sweet, sour, salty, and bitter--were obtained in a group of 25 SAD patients and 23 non-psychiatric subjects during the winter, after 2 weeks of 10 000 lux morning and evening light treatment, and during the summer. Relative to the comparison group, the SAD group was less sensitive to sweet taste during the winter. Sweet taste threshold in the SAD group normalized during the summer; however, 2 weeks of light treatment failed to alter sweet detection thresholds in the SAD group. Moreover, within the SAD group, season exerted significant effects on sweet, sour, and bitter detection, but it did not influence salt-detection thresholds. The findings represent the first demonstration of specific changes in taste perception associated with the self-report of carbohydrate craving in SAD and are discussed in terms of the development of sweet craving and the serotonin hypothesis of SAD.

Adult↗
PubMed2005

Seasonal allergy and seasonal decrements in athletic performance.

Allergic diseases are common in all age groups and locations around the world. In the United States, allergic diseases affect 20 to 40 million people annually, including 10% to 30% of adults and close to 40% of children. An estimated 15 million people in the United States have been diagnosed as having asthma, with this number on the rise. Concomitant asthma affects 67% of patients who have allergic rhinitis. As a result of the increase in ventilation during exercise, athletes in particular experience significant symptoms of allergy triggered by exposure to aeroallergens. The allergic response causes nasal and conjunctival congestion, tearing, breathing difficulties, pruritus, fatigue, and mood changes, which affect athletic performance. Systemic symptoms of anaphylaxis from allergy, although rare, can be life threatening. Several decades ago it was inconceivable that an athlete who had asthma could perform competitively, let alone win Olympic gold medals. Today, with proper diagnosis, education, and optimal therapeutic management, the allergic athlete can achieve great strides in all sports endeavors. To avoid seasonal allergic flares and maximize performance, the physician providing care for an athlete who has seasonal allergies must be aware of the climatic patterns of aeroallergen expression, and adjust exercise and pharmacologic regimens accordingly. This article summarizes the effects of allergic disease on exercise and highlights the challenges that seasonal allergy place on athletic performance. Doping considerations grant additional complexity to this issue and underscore the need for a competent, skillful, informed, and ethical approach to treating seasonal allergy in the competitive athlete.

Adolescent↗
PubMed1997

Seasonal variation in core temperature regulation during sleep in patients with winter seasonal affective disorder.

Nocturnal core temperature during sleep is elevated during depression compared with remission in nonseasonally depressed patients. Similarly, nocturnal core temperature is higher during winter depression compared with remission induced by light treatment in seasonal affective disorder (SAD) patients. We investigated whether nocturnal core temperature in SAD patients naturally becomes lower in summer (during remission) compared with winter (during depression). Twenty-four-hour core temperature profiles were obtained in winter and summer in 22 SAD patients and 22 controls. The nocturnal core temperature minima were lower in summer compared with winter in SAD patients (p < .005), but not controls (p > .4). The seasonal changes in nocturnal core temperatures in SAD patients may reflect a unique physiological responsiveness of SAD patients to the change of seasons, and may be intimately related to the seasonal disturbances of mood and energy that are characteristic of SAD.

Adult↗
PubMed1999

The role of genetic factors in the etiology of seasonal affective disorder and seasonality.

The study of the genetic basis of seasonal affective disorder (SAD), a condition where depressions in fall and winter alternate with nondepressed periods in the spring and summer, has recently received attention. The data on the genetics of seasonal affective disorders are of three types: 1. Familiality: Studies on the prevalence of psychiatric disorders among relatives of patients with SAD suggested a familial contribution to the development of SAD; 2. Heritability: A survey of a cohort of twins showed that genetic effects exert a global influence across a variety of behavioral traits and accounted for at least 29% of the variance in seasonality in men and women; 3. Molecular genetic research: two genetic variants related to serotonergic transmission, the 5-HTTLPR and the 5-HT2A-1438G/A gene promoter polymorphisms, are associated with SAD; the former but not the latter polymorphism is related to seasonality. Future research may clarify the role of different genes in the development of SAD.

Adult↗
PubMed1992

Seasonal panic disorder: a possible variant of seasonal affective disorder.

The present communication concerns a 30 year-old female patient with panic disorder in whom panic attacks appeared to be seasonally-related. Characteristically, attacks were more frequent and severe during the months of October to May with spontaneous remissions during the months of June to September. Since 70% of patients with seasonal affective disorder (SAD), a variant of affective illness characterized by recurrent winter depressions with remissions in summer, suffer from anxiety disorders, we propose that seasonal panic disorder may be a variant of SAD. Since SAD is associated with phase delay of circadian rhythms, some forms of panic disorder may be related to phase instability of circadian rhythms. Moreover, since administration of artificial bright light therapy is currently the most effective treatment for SAD, it is suggested that patients with panic disorder should be questioned as to whether their symptoms are seasonally related. If a positive association is established, these patients should be offered treatment with light therapy prior to or coincident with the institution of pharmacotherapy.

Adult↗
PubMed2003

Seasonal changes in avian song control circuits do not cause seasonal changes in song discrimination in song sparrows.

In seasonally breeding songbirds, brain nuclei of the song control system that act in song perception change in size between seasons. It has been hypothesized that seasonal regression of song nuclei may impair song discrimination. We tested this hypothesis in song sparrows (Melospiza melodia), a species in which males share song types with neighbors and must discriminate between similar songs in territorial interactions. We predicted that song sparrows with regressed song systems would have greater difficulty in discriminating between similar songs. Sparrows were housed either on short days (SD) and had regressed song circuits, or were exposed to long days and implanted with testosterone (LD+T) to induce full growth of the song circuits. We conducted two experiments using a GO/NO-GO operant conditioning paradigm to measure song discrimination ability of each group. Birds learned four (experiment 1) or three (experiment 2) pairs of song types sequentially, with each pair more similar in the number of shared song elements and thus more difficult to discriminate. Circulating T levels differed between the SD and LD+T groups. The telencephalic song nuclei HVc, RA, and area X were larger in the LD+T birds. The two groups of sparrows did not differ, however, in their ability to learn to discriminate between shared song types, regardless of the songs' similarity. These results suggest that seasonal changes in the song control system do not affect birds' ability to make difficult song discriminations.

Animals↗
PubMed2006

Seasonality of hip fractures and estimates of season-attributable effects: a multivariate ARIMA analysis of population-based data.

INTRODUCTION: This study examined seasonal variations in hip fracture rates using nation-wide, population-based data from Taiwan, a subtropical island with fairly uniform weather conditions (mean ambient temperature difference of 11.3 degrees C between peak summer and peak winter months). METHODS: All inpatients aged 45+ years included in the National Health Insurance Database between 1997 and 2003 and bearing an ICD diagnosis code 820 (fracture neck of femur) were included (n=102,792 cases). RESULTS: Auto-regressive integrated moving average (ARIMA) modeling showed significant seasonality and an association of monthly hip fracture admission rates with ambient temperature among both sexes and all three age groups, 45-64, 65-74, and 75+ years. Crude rates show a significant trough during May-August (late spring and summer), followed by a sharp increase in September, and a discernible peak during November-February (late autumn and winter). Adjusted for seasonality, trend, and month, hip fracture rates are significantly reduced among males (b=-0.280, p<0.001) and females (b=-0.341, p<0.001) with increases in the mean ambient temperature. The protective effect of temperature intensifies with age (b=-0.010, -0.241 and -2.263 among the groups aged 45-64, 65-74, and 75+ years, respectively). January (mid-winter) is independently associated with 0.339, 0.663 and 8.153 more hip fractures, respectively, among the three age groups, beyond the temperature effect noted above, and May (late spring) is associated with 0.168, 1.364, and 7.255 fewer fractures. Hours of sunshine and atmospheric pressure were not significant predictors. CONCLUSIONS: Based on our ARIMA regression coefficients for temperature, January, and May, we estimate that 32.1% of total hip fractures in January (the peak incidence month) are attributable to the season effect among seniors aged 75+ years, 17.2% among those aged 65-74 years, and 11.5% among those aged 45-64 years. We find that in a sub-tropical climate the effects of winter on hip fracture propensity is significant and increases with age. The policy implications are discussed.

Age Distribution↗
PubMed1993

Absence of seasonal variation in malaria parasitaemia in an area of intense seasonal transmission.

Parasitological surveys carried out in two villages of the Kilombero district of Tanzania indicated a very high prevalence of Plasmodium falciparum parasitaemia throughout the year (all ages mean prevalence = 69.2%) and a low, unstable prevalence of P. malariae (all ages mean prevalence = 4.5%). Fevers (temperature > or = 37.5 degrees C) in both children and adults showed irregular changes in prevalence over time, but there was no seasonal pattern. Neither was there seasonal variation in either P. falciparum parasite prevalence or parasite densities. This was despite marked seasonality in vectors caught in CDC light-traps and in estimated sporozoite inoculations determined by ELISA. The estimated mean annual inoculation rate was extremely high, over 300 infectious bites per person per year, the main vectors being members of the A. gambiae complex and Anopheles funestus. There was considerable variation between houses but even in houses with relatively low mosquito numbers the inoculation rate was sufficient to maintain a maximal P. falciparum prevalence. Heterogeneities in exposure cannot explain why the parasite prevalence is not always 100%. In areas of such high transmission, parasitaemias are likely to be determined mainly by the interaction of schizogony and anti-blood stage immunity, since parasites arising from new inoculations generally comprise only a small proportion of the total in the circulation. In any one individual, this will lead to periodic fluctuations in levels of parasitaemia. These are unlikely to show a close relationship to either seasonal variation in inoculations or to differences between households in the local inoculation rate.

Adolescent↗
PubMed1988

Seasonal control for an endemic disease with seasonal fluctuations.

In diseases exhibiting seasonal fluctuations, it may make sense to exploit the seasonality when devising control strategies. In this paper, the effect of using a seasonal screening program to control gonorrhea is examined. Ordinary differential equation models are analyzed with perturbation methods and an optimum seasonal control strategy is determined.

Communicable Disease Control↗
PubMed1980

Season of birth and season of hospital admission in bipolar depressed female patients.

The season of birth and season of hospital admission of 50 bipolar I and 42 bipolar II female patients were analyzed. Significant differences were found in the seasonal distribution of births in the two subgroups. The birth dates of most bipolar I patients showed a tendency to peak during spring and autumn, while bipolar II patients were born mostly in summer and winter. Bipolar I patients were hospitalized for mania mainly in spring and autumn, and for depression mainly in summer and winter. Examination of the seasonal variation of hospital admission for depression also revealed significant difference between bipolar I and bipolar II patients. The results support the validity of the bipolar I-bipolar II distinction and are in agreement with earlier findings.

Bipolar Disorder↗
PubMed1983

The use of a morantel sustained release bolus in the seasonal control of parasitic gastroenteritis in second-season cattle.

The efficacy of a morantel sustained release bolus was evaluated during the 1980 summer grazing season in 216 yearling, second-season cattle in nine trials in West Germany. In five trials individual farms were used, in which medicated and control groups could be grazed on adjacent pastures. In four additional trials medicated and control groups were maintained on separate farms where the sites and management practice were matched as far as possible. Faecal worm egg counts, herbage larval counts and weight gain were monitored at regular intervals throughout the season. The faecal output of gastrointestinal nematode eggs was reduced by 55.8 percent in the medicated animals during the period from May to early August, while worm egg counts were equal to that of the control animals during the later part of the season. Herbage larval counts were similar on pastures grazed by medicated and nonmedicated cattle. In the five trials where individual farms were used the average daily weight gains over the entire grazing period were 900 (+/- 222) g/animal/day in the medicated group compared with 826 (+/- 263) g/animal in the nonmedicated cattle, a non-significant advantage. No advantage for the treated over the control groups was detected in the additional 4 trials but this was attributed largely to the difficulty in obtaining comparable groups of animals in comparable grazing conditions in "matching" farms, leading to inter-farm variation.

Animals↗
PubMed1991

Genetic relationship between the HA genes of type A influenza viruses isolated in off-seasons and later epidemic seasons.

From January 1985 to March 1989, off-season viruses of H1N1 and H3N2 subtypes of influenza A viruses were isolated on five occasions in Japan. The HA gene sequences of the influenza A(H1N1) and A(H3N2) viruses isolated in Japan from 1985-9 were analysed and the phylogenetic tree for each subtype virus was constructed to determine any genetic relationship between viruses isolated in off-seasons and the epidemic viruses of the following influenza seasons. In one instance with H1N1 viruses in 1986 and in two instances with H3N2 viruses in 1985 and 1987, the spring isolates were genetically close to some of the winter isolates and were considered to be the parental viruses of the following influenza seasons. However, even in these cases, influenza viruses of the same subtype with different lineages co-circulated in Japan.

Amino Acid Sequence↗
PubMed2003

The effect of treatment with a 1% injectable formulation of moxidectin during the rainy season and at the beginning of the dry season on gastrointestinal nematodes in cattle from communal areas in Zimbabwe.

The effect of 1% moxidectin/cydectin at 0.2 mg/kg live weight on gastrointestinal nematodes and on the growth of calves, weaners and cows was investigated in five communal areas on the highveld of Zimbabwe. Three field experiments were carried out between March 1996 and June 1997. In experiment 1, treatment was administered in all five areas at the end of the rainy season in March 1996, followed by a further treatment at the beginning of the dry season in May/June 1996. In experiment 2, the treatment was administered in three areas at the end of the rainy season in March 1997. In experiment 3, treatment was administcred in one area at the beginning of the dry season in April 1997. Large numbers of eggs were present in the faeces of calves and weaners at the start of experiments 1 and 2. Epg values were lower in cows and in all age categories in experiment 3. There was a statistically significant reduction in epg values in calves, weaners and cows following treatment with a reduction of 90-99% in all cases except in cows in experiment 3, where no meaningful assessment was possible owing to the low egg counts in both the treated and control cows. The dominating larval types in faecal cultures were Cooperia and Haemonchus. Trichostrongylus, Oesophagostomum and Bunostomum were also found. Following treatment, Haemonchus was suppressed far more than Cooperia. This may be related to a longer residual effect against abomasal parasites like Haemonchus in comparison to small intestinal worms like Cooperia. Anthelmintic treatment conferred significant weight gain advantages (p < 0.05) on treated calves. weaners and cows. The weight gains are discussed in relation to disease and nutrition.

Animal Husbandry↗
PubMed2004

Is the season of birth association with psychosis due to seasonal variations in foetal growth or other related exposures? A cohort study.

OBJECTIVE: To investigate the association between season of birth and psychosis, and to assess whether any association is caused by seasonal fluctuations in foetal growth or other related exposures. METHOD: Cohort of 747 432 Swedish males and females born between 1973 and 1980 and followed up from 16 years of age to 31 December 1999. Psychiatric admissions were identified using the Swedish Inpatient Discharge Register. The analysis is based on the 696 025 subjects with complete data. RESULTS: A total of 506 (0.07%) subjects developed schizophrenia and 879 (0.13%) non-affective non-schizophrenic psychoses. There was a moderate increased risk of schizophrenia amongst winter births, hazard ratio 1.23 (95% confidence interval 0.96-1.59), but this did not reach conventional levels of statistical significance. There was no association with non-affective psychoses. We found no evidence that associations were confounded by measures of foetal growth or maternal socioeconomic position. There was no evidence that seasonal effects on schizophrenia differed in men and women. CONCLUSION: Season of birth associations with schizophrenia do not appear to be confounded by birth-related exposures.

Adolescent↗
PubMed2000

The possible effect of seasonal mood changes on the seasonal distribution of myocardial infarction.

The incidence of acute myocardial infarction is increased in the winter months. Seasonality of mood and behavior is common throughout the general population. Increased cardiovascular morbidity and mortality in patients with depressive disorders have been well documented. The author suggests that seasonal mood changes may contribute to the increased incidence of acute myocardial infarction in the winter. The author further suggests that patients with cardiovascular disorders who suffer from seasonal mood changes should be identified and receive the appropriate treatment for seasonal depressive symptoms that may improve the quality of life for these individuals and reduce their incidence of acute myocardial infarction.

Affect↗
PubMed1984

Seasonal aggression independent of seasonal testosterone in wood rats.

Levels of inter-male aggression, both in laboratory encounters and in the field, rise dramatically during the breeding season, closely paralleling the seasonal rise in testosterone. However, post-pubertally castrated males also show the dramatic seasonal rise in aggression in laboratory encounters with castrated opponents and show no decrement in fighting ability when paired with intact opponents, clearly demonstrating the independence of seasonal aggression from the proximate modulating effects of testosterone in wood rats.

Acclimatization↗
PubMed1992

'Horoscope effect' not only for seasonal but also for non-seasonal allergens.

We report on the relation between the month of birth and the chance of developing an IgE antibody response as found in a study sample of 150,000 subjects. Our results confirm that for the three seasonal allergens birch pollen, grass pollen and house dust mite, an increased relative risk was found for subjects born up to 3 months before the main season for that allergen in The Netherlands. For cat and dog allergy an increased relative risk was found from November to January, perhaps reflecting increased exposure to these pets during the winter. Surprisingly, however, also for egg white and cow's milk a clearly increased relative risk was found from November to January and a decreased relative risk in May. These data support the hypothesis of a 'sensitive' period in the first months of life during which allergen exposure is more likely to prime for an allergy later in life. The results with the non-seasonal allergens suggest that another seasonal factor exists which early in life assists (or prevents) priming by allergen.

Allergens↗