Genome-wide scan in a nationwide study sample of schizophrenia families in Finland reveals susceptibility loci on chromosomes 2q and 5q

We have previously carried out two genome-wide scans in samples of Finns ascertained for schizophrenia from national epidemiological registers. Here, we report data from a third genome scan in a nationwide Finnish schizophrenia study sample of 238 pedigrees with 591 affected individuals. Of the 238 pedigrees, 53 originated from a small internal isolate (IS) on the eastern border of Finland with a well established genealogical history and a small number of founders, who settled in the community 300 years ago. The total study sample of over 1200 individuals were genotyped, using 315 markers. In addition to the previously identified chromosome 1 locus, two new loci were identified on chromosomes 2q and 5q. The highest LOD scores were found in the IS families with marker D2S427 (Z(max) = 4.43) and in the families originating from the late settlement region with marker D5S414 (Z(max) = 3.56). In addition to 1q, 2q and 5q, some evidence for linkage emerged at 4q, 9q and Xp, the regions also suggested by our previous genome scans, whereas, in the nationwide study sample, the region at 7q failed to show further evidence of linkage. The chromosome 5q finding is of particular interest, since several other studies have also shown evidence for linkage in the vicinity of this locus.

Chromosome 1 loci in Finnish schizophrenia families

We have earlier reported evidence for linkage to two regions on chromosome 1q32--q42 in schizophrenia families collected for two separate studies in Finland. Here we report the results of a fine mapping effort aimed at further definition of the chromosomal region of interest using a large, population-based study sample (221 families, 557 affected individuals). Most affecteds (78%) had a DSM-IV schizophrenia diagnosis and the remaining had schizophrenia spectrum disorders. We genotyped a total of 147 microsatellite markers on a wide 45 cM region of chromosome 1q. The results were analyzed separately for families originating from an internal isolate of Finland and for families from the rest of Finland, as well as for all families jointly. We used traditional two-point linkage analysis, SimWalk2 multipoint analysis and a novel gamete-competition association/linkage method. Evidence for linkage was obtained for one locus in the combined sample (Z(max) = 2.71, D1S2709) and in the nuclear families from outside the internal isolate (Z(max) = 3.21, D1S2709). In the families from the internal isolate the strongest evidence for linkage was obtained with markers located 22 cM centromeric from this marker (Z(max) = 2.30, D1S245). Multipoint analysis also indicated these loci. Some evidence for association with several markers was observed using the gamete-competition method. Interestingly, the strongest evidence for linkage in the combined study sample was obtained for marker D1S2709, which is an intragenic marker of the DISC1 gene, previously suggested as a susceptibility gene for schizophrenia. These results are consistent with the presence of susceptibility gene(s) in this chromosomal region, a result also implied in other recent family studies of schizophrenia.

Seasonal affective disorder and serotonin-related polymorphisms

Disturbances in central serotonergic systems have been hypothesized to be involved in seasonal affective disorder (SAD). Association between SAD and the shorter allele of the serotonin transporter promoter repeat length polymorphism (5-HTTLPR) has been reported in an American sample. We have genotyped 82 SAD patients and 82 healthy controls from Sweden, Finland, and Germany for this and five other polymorphisms in the genes coding for serotonin receptors 5-HT2A and 5-HT2C, tryptophan hydroxylase and white. No associations with SAD or seasonality (seasonal variations in mood and behavior) were detected. Although minor effects cannot be excluded, our results suggest that these polymorphisms do not play a major role in the pathogenesis of SAD in the northern European population.

Bright light as an inhibitor of adenosine transport

The administration of bright light rapidly improves subjective alertness and is likely to have direct effects on the activity of neurons in the suprachiasmatic nucleus (SCN). Bright light may enhance wakefulness by interrupting the increase in extracellular adenosine concentration with brain metabolism during the day. Exposure to bright light is hypothesized to induce the inhibition of adenosine transport, promoting both subjective alertness and activation measured objectively, and to activate the cholinergic neurons of the reticular system and those using gamma-aminobutyric acid as a neurotransmitter in the SCN.

Bright light improves vitality and alleviates distress in healthy people

BACKGROUND

The relative shortage of light during the decreasing photoperiod may compromise well-being. Earlier studies suggest that bright-light exposure may be of help to alleviate winter-bound symptoms.

METHODS

We carried out a field study with exposure to bright light on office employees during winter.

RESULTS

Repeated bright-light exposure improved vitality and reduced depressive symptoms. The benefit was observed not only in healthy subjects with season-dependent symptoms but also in those not having the seasonal variation.

CONCLUSIONS

Bright-light exposure during winter appears to be effective at improving the health-related quality of life and alleviating distress in healthy subjects.

CLINICAL IMPLICATIONS

Administration of bright light is a useful option to improve vitality and mood among subjects working indoors in wintertime. LIMITATIONS OF STUDY: Our field setting used self-reports, not interviews, for the assessment of outcome.

Association of low serum total cholesterol with major depression and suicide

BACKGROUND

It has been suggested that low serum total cholesterol is associated with an increased risk of suicide.

AIMS

To study the association between serum total cholesterol, depression and suicide using versatile, prospective data.

METHOD

A total of 29,133 men aged 50-69 years were followed up for 5-8 years. Baseline blood samples were analysed for serum total and high-density lipoprotein cholesterol concentrations. Self-reported depression was recorded, data on hospital treatments due to depressive disorders were derived from the National Hospital Discharge Register and deaths from suicide were identified from death certificates.

RESULTS

Low serum total cholesterol was associated with low mood and subsequently a heightened risk of hospital treatment due to major depressive disorder and of death from suicide.

CONCLUSIONS

Our results suggest that low serum total cholesterol appears to be associated with low mood and thus to predict its serious consequences.

Short note: melatonin-dependent infertility

Melatonin may be a key factor in the regulation of seasonal variation in gonadal activity. The circadian disturbances related to reproduction are probably subsequent to the seasonal change. Moreover, melatonin might also be considered essential for both spermatogenesis and folliculogenesis. Exposure to bright light, suppressing the concentration of melatonin in circulation, is hypothesized to be useful in treatment of both male and female infertility in couples with abnormal melatonin metabolism.

Melatonin-dependent infertility

Melatonin may be a key factor in the regulation of seasonal variation in gonadal activity. The circadian disturbances related to reproduction are probably subsequent to the seasonal change. Moreover, melatonin might also be considered essential for both spermatogenesis and folliculogenesis. Exposure to bright light, suppressing the concentration of melatonin in circulation, is hypothesized to be useful in treatment of both male and female infertility in couples with abnormal melatonin metabolism.

Randomized trial of physical exercise alone or combined with bright light on mood and health-related quality of life

BACKGROUND

So-called atypical depressive symptoms (carbohydrate craving, prolonged sleep, weight gain, increased appetite) frequently emerge in association with low illumination to which people are ordinarily exposed indoors, or even outdoors at extreme latitudes in wintertime. Our objective was to analyse the effect of physical exercise alone or combined with bright light on mood and the health-related quality of life during winter.

METHODS

We carried out a randomized controlled trial on 120 indoor employees in southern Finland between November and January. The subjects were allocated to supervised fitness training under bright (2500-4000 lx) or ordinary (400-600 lx) light conditions in a gym 2-3 times weekly for 8 weeks, or supervised relaxation training once a week over the same period as active placebo. We collected questionnaire data on the changes in mood and health-related quality of life after 4 and 8 weeks of training, and after 4 months follow-up.

RESULTS

Fitness training in bright light resulted in greater relief from atypical depressive symptoms and more vitality than in ordinary room light. Compared with relaxation alone, the former regime improved general mental health and social functioning in addition to the improvement in depressive symptoms and vitality, whereas the latter only increased vitality.

CONCLUSIONS

Supervised physical exercise combined with exposure to bright light appears to be an effective intervention for improving mood and certain aspects of the health-related quality of life in wintertime. This effect appears unrelated to the history of season-dependent symptoms, being noticeable among healthy individuals.

Extrapineal melatonin and exogenous serotonin in seasonal affective disorder

Visible light inhibits the binding of melatonin and serotonin to cultured human peripheral blood mononuclear leukocytes (PBMLs) in winter. The decreased binding switches the metabolism in PBMLs towards serotonin synthesis, resulting in the reduced production of melatonin. The ingestion of L-tryptophan during the day is hypothesized to increase the levels of melatonin, released from the gastrointestinal tract, in patients with winter seasonal affective disorder (SAD). Due to the relative shortage of light, coincident with a predisposed metabolic error, there would be no switch towards serotonin synthesis among winter SAD patients in winter. The rate of serotonin synthesis could thus remain inadequately low to maintain optimal mood in winter SAD patients.

Magnetoreception attributed to the efficacy of light therapy

A group of specialized photoreceptors are suggested to amplify the weak interaction of the geomagnetic field with a single electron spin to the level of photon detection, resulting in a modulation of the response to light. Under exposure to rotating magnetic field, the size of pinealocytes is bigger at night than during the day in spring, but there is no day-night difference in autumn. Specialized photoreceptors are hypothesized to modulate the response of the photoreceptive system to light, and the pineal response to a magnetic stimulus, in patients with winter seasonal affective disorder (SAD). This could explain why some winter SAD patients show excessive sensitivity to light in winter.

Seasonal affective disorder

Seasonal affective disorder (SAD) is a form of recurrent depressive or bipolar disorder, with episodes that vary in severity. Seasonal patterns of depressive episodes are common, but SAD seems to be less common than such patterns suggest. SAD was at first believed to be related to abnormal melatonin metabolism, but later findings did not support this hypothesis. Studies of brain serotonin function support the hypothesis of disturbed activity. The short-allele polymorphism for serotonin transporter is more common in patients with SAD than in healthy people. Atypical depressive symptoms commonly precede impaired functioning, and somatic symptoms are frequently the presenting complaint at visits to family physicians. The best treatment regimens include 2500 Ix of artificial light exposure in the morning. When patients seem to have no response or to prefer another treatment, antidepressants should be considered.

One pacemaker in seasonal affective disorder

Patients with winter seasonal affective disorder (SAD) often have abnormalities in the resetting of their circadian clock. The circadian cycle appears to be variable across days among these patients, deviating from the exact 24 hours, and peaking at unstable times. The findings suggest that the mean free-running circadian period is longer in winter SAD patients compared to healthy subjects. It is hypothesized that there would be a singular circadian pacemaker in the patients against the two pacemakers in healthy subjects.

Vitamin D and serotonin in winter

Calcitriol accumulates in the nuclei of adrenal medullary cells, stimulating the tyrosine hydroxylase gene expression. The transcription of the CREM gene is induced by adrenergic input to the pineal gland at night. Depending on the photoperiod of the prior night length, the CREM gene is either subsensitive or supersensitive to induction. Guided by the memory of past photoperiods, the induced changes in melatonin synthesis may mediate either the inhibitory or stimulatory effects on bodily functions. Calcitriol might inhibit the binding of melatonin to the nuclear retinoid Z receptors, which would result in the increased serotonin levels. Serotonin synthesis is hypothesized to be dependent on the duration of light exposure the previous summer.

A developmental approach to severe depression

Reduced rapid-eye-movement (REM) sleep latency and increased REM sleep activity are associated not only with increased risk of recurrent depressive episodes but also with shortened time to the onset of subsequent episodes. Increased REM sleep activity might be a sign of attempt to excite the photic-responsive brain regions during the night, and there is a negative correlation between regional blood flow in the dorsolateral prefrontal cortex and REM sleep. The relative deactivation of the dorsolateral prefrontal cortex as a result of a developmental abnormality could explain the increased REM sleep activity during the first half of the night and the subsequent terminal insomnia among depressed subjects.

Dependence of the variation in alertness on the pineal gland

There is a diurnal variation in the pineal serotonin content, with a maximum at 7-8 h after the onset of light and a minimum at 3-4 h after the onset of darkness in rats. The levels of serotonin and melatonin can rapidly be altered by changing the level of ambient light. The diurnal changes in serotonergic activity are hypothesized to counteract two phenomena. First, the increased levels of serotonin would decrease the high propensity to drowsiness in the afternoon. Second, the decreased levels of serotonin would also decrease the high propensity to waking up at night, which occurs because of decreased melatonin secretion.

Psoralens in association with seasonal affective disorder

The pathogenesis of seasonal affective disorder (SAD) has been attributed to abnormal melatonin metabolism. Perorally administered psoralens increase the daytime levels of melatonin via the competitive inhibition of hepatic melatonin metabolism. Some findings among SAD patients are parallel to those observed after the administration of a psoralen in healthy subjects. It is hypothesized that there may be a circulating psoralen-like substance which affects SAD patients under a low level of illumination. Exposure to bright light during the daylight period would normalize the abnormal effect independently of the season.

Suppression of melatonin secretion by bright light in seasonal affective disorder

Eleven patients with winter seasonal affective disorder and 10 healthy controls were exposed to light of 3300 lux for 5 min and for 1 hour respectively on consecutive evenings at 22:00 hours during winter and summer. In the winter, the measurements were undertaken both before and after the treatment with bright light for 2 weeks. In the summer, there was no treatment. Melatonin concentration in saliva and subjective sleepiness were measured at 22:00 and 23:00 hours on each test. There was no significant difference in the suppression of melatonin in response to the light tests between the patients and the controls. Exposure to light reduced the level of subjective sleepiness more among the patients compared to the control subjects. This reduction was not associated with the change in melatonin secretion nor the improvement in depressive symptoms.

Pavlovian conditioning may partly explain the effects of light therapy

Explicit pairings of a non-photic stimulus and exposure to light are capable of inducing behavioural responses that are characteristic of the resetting of the circadian system by light as well as cellular effects in the neural regions that are normally activated only by light. The setting of light therapy as used for treatment of winter seasonal affective disorder resembles that of Pavlovian conditioning. The conditioning may provide a rationale for the sustained therapeutic response to light treatment observed to last for the rest of the season in some of the patients treated with light.

Patients excluded from an antidepressant efficacy trial

BACKGROUND

The impact of exclusion criteria on antidepressant trials is rarely investigated and poorly understood. We describe specific reasons for exclusion from a double-blind comparative trial and analyze the selection procedure and its impact on treatment outcome.

METHOD

A 6-week randomized double-blind trial for depressive disorders recruited patients through outpatient psychiatric services, private offices, and health care centers. Of the 612 consecutive patients interviewed for a diagnosis according to DSM-III-R, 209 (34%) finally entered the trial.

RESULTS

86% of the included patients had no comorbid psychiatric disorder, whereas a third of those excluded had at least one (p < .00001). Patients were excluded for having chronic alcohol or drug misuse (17%), receiving antidepressant drugs (15%), or having physical problems precluding their ability to take either of the drugs studied (14%). Some patients could not be included because of a referral to other modes of treatment (19%) or organizational difficulties (16%). The excluded patients less often suffered from major depressive disorder than those who were included in the trial. In particular, patients excluded because of suicidal thoughts or intent more often had a history of previous major depressive episodes (p = .006) compared with the included patients. The most important sociodemographic factors related to exclusion from the trial were male sex and unmarried status.

CONCLUSION

Patients with previous depressive episodes or comorbid disorders were more likely to be excluded from the antidepressant efficacy trial. Data on the efficacy of antidepressant drugs on this patient population are still only infrequently obtained.

Moclobemide and fluoxetine in treatment of seasonal affective disorder

Of a total of 581 consecutive depressed subjects attending psychiatric services of 6 centres in Finland, 183 patients were eligible and completed a 6-week randomised double-blind trial with either moclobemide or fluoxetine. Of these, 32 (17.5%) patients met the DSM-III-R criteria for mood disorder with a seasonal (winter) pattern and 19 patients (10.5%) met the original criteria for seasonal affective disorder (SAD). There were no significant difference in the antidepressive response to the treatment between the patients with SAD and other depressive disorder. The treatment of 6 weeks with either moclobemide (300-450 mg daily) or fluoxetine (20-40 mg daily) resulted in a full remission in 15 (52%) patients with SAD and in 44 (37%) patients with other depressive disorder. Altogether, 23 (79%) and 83 (70%) patients, respectively, got significant benefit from the treatment. The improvement in the health-related quality of life in terms of ability to work was significantly more extensive in the patients with SAD assigned to receive moclobemide compared with the other depressive patients allocated to the same medication. Subjects who in addition met the operational criteria for atypical depression were equally distributed into the SAD and other depressive patient groups.

Seasonal variation in bipolar disorder

BACKGROUND

In patients with bipolar disorder, admissions for manic and depressive episodes frequently display a seasonal pattern. We examined this variation and compared the patterns with the seasonal admission rates for schizophrenia.

METHOD

Patients with bipolar disorder or schizophrenia were identified from the Finnish Hospital Discharge Register of in-patient admissions to all psychiatric hospitals during the years 1969-91. They were included in the analysis if the first admission had occurred before 30 years of age. A total of 295 bipolar patients were found, and a sample of 295 schizophrenic patients was randomly selected for comparison.

RESULTS

There was no seasonal variation among all hospital admissions for bipolar disorder or schizophrenia. However, the first admission for a depressive compared with a manic episode of bipolar disorder occurred significantly more often in the autumn (33% v. 21% respectively). The peak difference occurred during the week after the autumnal equinox in September.

CONCLUSION

Our findings suggest that there is no seasonal variation in bipolar disorder, although in some patients the clinical course might be influenced by the autumn, as far as the likelihood of a first admission for depression is concerned.

Possible pathophysiological mechanisms regulating food intake in seasonal affective disorder

Noradrenaline, estrogen, neuropeptide Y and galanin are all involved in regulation of eating behaviour. Based on a recent case report on seasonal affective disorder (SAD), there is evidence of decreased insulin sensitivity. Reduced insulin sensitivity may increase the transcriptional activity of the neuropeptide Y gene in the medial basal hypothalamus and subsequent ingestion of food. Decreased availability of estrogen may also increase the levels of neuropeptide Y, leading to decreased release of noradrenaline from the ventromedial hypothalamus. The increased noradrenaline content may increase the concentration of galanin, which will decrease the circulating levels of insulin and increase the pace of transcription of the neuropeptide Y gene. Among some SAD patients, it is possible that the sustained ingestion of high-fat diet will rather activate the transcription of the neuropeptide Y gene than deactivate it, indicating a defect in macronutrient selection.

Prevention of winter seasonal affective disorder by bright-light treatment

In patients with winter seasonal affective disorder (SAD) the onset of a depressive episode is probably associated with the decreasing amount of light during the autumn. A highly predictable onset of a recurrent depressive episode with seasonal pattern provides a rationale for testing the efficacy of bright-light treatment as a preventive measure. Twelve out-patients with winter SAD were assigned to start bright light treatment either when they were well, or not to start it until the first symptoms of depression had already emerged. The severity of depressive symptoms was prospectively rated for a parallel randomized comparison. Bright light given well in advance of the emerging symptoms prevented a depressive episode. Clinical remission was significantly more frequent in the former subgroup of the patients in January and in March. To sum up, bright light can be successfully administered as prophylactic treatment for the prevention of winter SAD.

Dopamine and circadian rhythms in seasonal affective disorder

In seasonal affective disorder, there is evidence of both increased and decreased dopaminergic transmission in the central nervous system. Bright light treatment appears to normalize these abnormalities among the patients. Dopamine is suggested to have a direct effect on heat loss via the vascular system, in addition to its capability of resetting the circadian system by changes in both heat production and heat loss. Therefore, impaired dopamine availability may result in a decreased heat loss response to an endogenous thermal challenge as well as abnormalities in the generation of circadian rhythms in some patients with seasonal affective disorder.

Effects of bright light on sleepiness, melatonin, and 25-hydroxyvitamin D(3) in winter seasonal affective disorder

Sixteen patients with winter seasonal affective disorder and 13 healthy controls were exposed to 3300 lx of cool-white fluorescent light for either 1 hour or 15 min in the morning for 2 weeks during the winter. Subjective sleepiness, melatonin concentration in saliva, and serum 25-hydroxyvitamin D(3) concentration were measured before and after the 2-week trial as well as the following summer when the patients were well. There were no significant differences in the baseline values between the patients and healthy subjects. No significant differences in the outcome measures were observed in the patients or the controls in the two groups of each after the trial. The exposure to bright light resulted in a significant decrease in subjective sleepiness early in the evening in the patients but not in the control subjects. The reduction of depressive symptoms was associated with the decrease in subjective sleepiness but not with the changes in the melatonin or vitamin D concentrations.

Effects of exposure to morning bright light in the blind and sighted controls

Seven blind subjects and 11 sighted controls were exposed to 3300 lux of cool-white fluorescent light for either 1 h or 15 min in the morning for 2 weeks during the winter. Serum 25-hydroxyvitamin D3 concentration, melatonin concentration in saliva, body temperature from the armpit, subjective sleepiness, and depressive symptoms were measured before and after the 2-week trial. The intervention resulted in a significant elevation in the concentration of melatonin at 21.00 hours in the healthy controls but at 23:00 hours in the blind subjects. The body temperatures measured were increased in the controls but decreased in the blind in the morning following the cessation of the intervention, and these opposite changes resulted in significant differences in the temperatures between the two groups. The decreases in the body temperature were associated with the increases in the levels of melatonin in the blind but not in the controls. Bright light administered in the morning decreased subjective sleepiness and improved mood in the healthy controls and in the blind subjects as well. The intervention had no effect on the levels of vitamin D in either of the two groups.

A mechanism of action underlying the antidepressant effect of light

In patients with winter seasonal affective disorder (SAD), delayed and reduced responses to corticotropin-releasing factor (CRF) have been observed. Bright light treatment has been shown to normalize these responses. In depressed patients, there is increased CRF activity in the evening during the normally quiescent period between 19.30 and 22.00 hours. In patients with winter SAD, the level of subjective sleepiness is increased in the evening between 20.00 and 21.00 hours. In the latter group of patients, the CRF activity may be increased in the evening and associated with the increased level of subjective sleepiness. This increased activation is suggested to be normalized by bright light treatment, acting primarily on neurons of the paraventricular nucleus of the hypothalamus.

Estrogen could control photoperiodic adjustment in seasonal affective disorder

Women are affected by winter seasonal affective disorder (SAD) more often than men. The female/male ratio is reported to range from 2:1 to 40:1 in samples of patients with winter SAD. It is suggested that this preponderance of women is based on the action of the ovarian steroid hormones estrogen and progesterone. However, the detailed mechanisms of action are not well understood to date. A new hypothesis claims that, in women with winter SAD, decreased levels of estradiol in the ventromedial hypothalamus are associated with the occurrence of atypical symptoms of depression, including increased daytime sleepiness and hypersomnia during the winter.

The influence of comorbid disorders and of continuation light treatment on remission and recurrence in winter depression

The objectives of this prospective study were to investigate the influence of comorbid disorders and that of continuation light treatment on remission rates and on a subsequent onset of a depressive episode in outpatients (n = 20) with winter depression. The effects of light treatment were evaluated by the structured clinical interviews and by the self-ratings of mood scored monthly for a follow-up period of 1 year. The remission rates of the patients (n = 8) who proceeded light treatment until the late winter were not significantly different from those of the patients (n = 6) who stopped treatment early during the winter. A more extensive variation in the rates during the year was observed in the former group of patients among whom the comorbid avoidant personality was more frequent, indicating an increased risk of an earlier onset of a depressive episode.

Involvement of melatonin and serotonin in winter depression

The phase of circadian rhythms can be shifted by exposure to light. Most patients with winter depression are suggested to have a phase delay in their circadian rhythms. The efficacy of light in treatment of winter depression is thought to be associated with the phase shifting effect of light. In addition to light, melatonin and serotonin can cause phase shifts of the rhythms. The concerted action of these indoleamines may underly the finding that light has an antidepressant effect, independently of time of day or circadian phase of an individual.

Prolactin in winter depression

Women with winter depression have low serum prolactin concentration that is independent of both season and efficient bright light treatment administered in winter. A defect of neural pathways afferent to the paraventricular nucleus may explain these findings. Estrogen is thought to play a key role in modulation of the rhythmic responses in winter depression.

The molecular basis for winter depression

A pulse of light is capable of inducing the circadian phase-dependent gene expression in neurons. The phase or amplitude of the circadian rhythms can be modulated by critically timed exposures to light. A significant heritability for the light-induced responses has been observed in hamsters. In humans, light has been used for treatment of the light-dependent winter depressive disorder. A genetic predisposition for high responsiveness to light may occur in patients with winter depression. The altered gene expression induced by light may account for a unique sensitivity to light and mediate the anti-depressant effect of light treatment.

Suicides among draftees: biphasic occurrence of suicide during military service

We analyzed all suicides among draftees during the 10-year period 1981-1990. The distribution of 50 suicides followed a bimodal curve with the first peak occurring 20-60 days from the beginning of the military service and the second peak during the early specialization training. Suicides committed during the basic training period were characterized by the absence of preceding alcohol intoxication, which was significantly more often seen in the suicides committed later during service. Most of the cases had been in contact with the medical personnel a short time before suicide. We discuss preventive measures, such as health education directed to both draftees themselves and the medical personnel.

Effects of morning light treatment on subjective sleepiness and mood in winter depression

The effects of morning light treatment on mood, subjective sleepiness and body temperature were investigated with 13 outpatients with winter depression and 13 healthy controls. Bright light for 1 h daily for 2 weeks resulted in a significant reduction in depression ratings and evening subjective sleepiness in the patients compared with the healthy controls. Even a short 15-min exposure to light daily produced these changes.

Light treatment for seasonal affective disorder: theoretical considerations and clinical implications

The concept of seasonal affective disorder (SAD) includes any depression whose onset is related to a certain season. Reduced environmental light is hypothesized to be the main precipitating factor of winter depression. Light treatment is used to prevent the onset of depressive episodes and to reduce depressive symptoms in patients with depression during winter months. The mechanisms of action which lead to the well-documented antidepressant response are still unknown. Several hypotheses of the pathogenesis of SAD are discussed, and the clinical practice of light treatment is reviewed.

Effects of morning light treatment on subjective sleepiness and mood in winter depression

The effects of morning light treatment on mood, subjective sleepiness and body temperature were investigated with 13 outpatients with winter depression and 13 healthy controls. Bright light for 1 h daily for 2 weeks resulted in a significant reduction in depression ratings and evening subjective sleepiness in the patients compared with the healthy controls. Even a short 15-min exposure to light daily produced these changes.

The shortening of the photoperiod may alter gene expression in winter depression

Winter depression is characterised by recurrent major depressive episodes with a seasonal (winter) pattern. Reduced exposure to daylight due to shortening of the day has been hypothesized to trigger off the onset of a depressive episode. Daily exposures to light during the dark period have been used as the treatment of choice for winter depression. A genetic predisposition for high responsiveness to light is thought to exist in patients with winter depression. Altered gene expression may contribute to the unique sensitivity and mediate the antidepressant effects of light.

Effects of light treatment on sleep structure in seasonal affective disorder

Twelve outpatients with seasonal affective disorder (depression, winter type) were treated by 1 h of bright light exposure for five mornings. The intervention produced a significant reduction in depression scores, but no change was seen in the sleep electroencephalographic variables recorded after light treatment. Significant changes were seen, however, in ratings of subjective sleepiness. The acrophase of the circadian sleepiness rhythm was phase advanced, the mean level of the sleepiness rhythm was diminished, and the mean values of sleepiness scores were reduced at 8 and 10 a.m. This minimal influence of bright light on sleep structure is unlikely to explain the well-documented antidepressant effect.

Frequencies of seasonal major depressive symptoms at high latitudes

A modified depression rating scale was distributed to a sample of the adult Finnish population (n = 1000) in November 1991. No dependence on latitude (60 degrees N-70 degrees N) was seen in the occurrence of depression. The depressed subjects (n = 54) were reevaluated the following May, and four cases with seasonal affective disorder were found. The results suggest that high latitudes with large variations in the daily lightperiod may not be responsible for high prevalence of major depression with a seasonal pattern.