Is Winter Depression

a Bipolar Disorder?

David M. White, Alfred J. Lewy, Robert L. Sack, Mary L. Blood, and David L. Wesche Sixty-one

winter

Schedule

for Affective

Inventory,

depressive

were

evaluated

following

Also, few patients of winter

winter

for evidence

and Schizophrenia-Lifetime

only nine (15%) could be considered

the summer symptoms

patients

Disorders

depression,

few

bipolar. On prospective showed

illness.

Using

and the General evaluation

patients

were

the

Behavior

of patients during

signs of manic or hypomanic

had a family history of bipolar illness. When depression,

of bipolar

Version

symptoms.

asked to evaluate

lack of energy was found to be the most prominent

feature of the

syndrome. 0

1990

by W. B. Saunders

Company.

P

ATIENTS WITH A SEASONAL PATTERN of depression typically become depressed each winter with remission of depressive symptoms occurring in the springtime. ‘,* In the first case in which bright artificial light was used to treat winter depression, the patient was diagnosed as having a bipolar disorder.3 During the first major study of the clinical features of patients with seasonal affective disorder (SAD), Rosenthal et al. diagnosed the majority as bipolar I or II; only 7% of patients were diagnosed as having a unipolar illness (Table l).’ Bipolar II patients experience episodes of hypomania, as well as major depression, the former condition characterized by elevated mood, expansiveness, or irritability.lF4 Unlike mania, hypomania by definition does not cause marked impairment in social or occupational functioning or lead to hospitalization. Since their initial study, Rosenthal and other National Institute of Mental Health (NIMH) researchers have found that more than 80% of their seasonal affective disorder (SAD) patients have diagnoses of bipolar II disorder.5 Most of these patients were found to become depressed in the winter and to experience hypomania in the spring or summer. Whereas initial studies of winter depression suggested that this patient group is composed predominantly of patients with bipolar illness, subsequent studies have obtained mixed findings regarding the primary diagnoses of these patients (Table 1). Thompson and Issac@ and Wirz-Justice et al.’ found that most of their winter depressive patients met diagnostic criteria for bipolar I or II disorders, while Thase et a1.8 and Yerevanian et al.’ diagnosed the majority of their patients as having unipolar depressive conditions. Recognition of bipolar II illness as a distinct disorder is relatively recent in psychiatry, and diagnosis of this disorder is made with poor reliability.” In studies of winter depression, researchers have attempted to maximize diagnostic reliability and accuracy by using standardized diagnostic instruments. The Lifetime Version of the Schedule for Affective Disorders and Schizophrenia (SADS-L)” has been used to achieve Research and Diagnostic Criteria (RDC).4 However, while interrater agreement for the SADS-L and RDC generally are high, reliability is

From the Department of Psychiatry, Oregon Health Sciences University, Portland, OR. Address reprint requests to Robert L. Sack, M.D., Department of Psychiatry, L-469, Oregon Health Sciences University, 3181 S WSam Jackson Park Rd. Portland, OR 97201. o I990 by W.B. Saunders Company. 0010-440x/90/3103-0003%03.00/0 196

Comprehensive

Psychiatry,

Vol. 3 1, No. 3 (May/June),

1990:

pp 196-204

IS WINTER DEPRESSION A BIPOLAR DISORDER?

Table 1. Affective

Study

Disorders

of Winter

Method of Recruitment

Location

197

Depression

Patients

Diagnostic Instrument

n

Rosenthal’ (1984)

Bethesda, MD

Newspaper ads

SADS-L

29

Thase’ (1986)

Pittsburgh, PA

SADS-L

18

Thompson’ (1988)

Charing Cross, England Basel, Switzerland

RDC criteria, monthly followup DSM Ill, life history

51

Wirz-Justice’ (1986) Yerevaniar? (1986)

Rochester, NY

Psychiatric outpatient clinic referrals Physician referrals, newspaper articles Physician referrals, newspaper articles Physician referrals, newspaper ads

DSM Ill, life history

22

9

Type of Affective Disorder (%I BPII: 76 BP I: 17 UP: 7 BPII: 17 UP: 83 8Pll:37 BP I: 18 UP: 45 8Pll:77 BP I: 18 UP: 5 BP: 11 UP: 89

Abbreviations: BP, bipolar; UP, unipolar.

comparatively poor for the diagnosis of hypomania. 4~12Because patients usually feel better following episodes of depression, it is often difficult for clinicians to ascertain if this mood state is a normal response to coming out of a depression or is symptomatic of the hypomania clinical characteristic of bipolar II illness.13 Retrospective diagnosis of bipolar II disorder is difficult, particularly when the patient is interviewed while depressed. Recent investigations of bipolar II patients show that there are characteristics in addition to current hypomanic symptoms that may help differentiate these patients from those with unipolar illness. Family studies indicate differences in genetic risk among affective disorders, with relatively low risk for infrequent-episode unipolar disorder and higher risk for bipolar II disorder.‘0~‘4-‘7 Also, bipolar II depressed patients typically respond positively to lithium carbonate, whereas unipolar patients respond less well, if at all, to this treatment.‘*-*’ In addition to studying the family history and drug responsiveness of particular patients, clinicians may try to gain knowledge of affective disorders by using self-report measures that assess a wide range of behaviors and tend to be less influenced by the patient’s current mood state. METHOD

Subjects Over a 3-year period, 61 subjects with winter depression were studied in several different research protocols at the Oregon Health Sciences University. Subjects were recruited primarily by means of newspaper advertisements. They were selected for inclusion in studies based on their responses to personal history and symptom questionnaires, as well as from data gained during clinical interviews by psychiatrists and psychologists. To be included in the studies, subjects had to have a history of recurrent depression during the winter with remission of depressive symptoms in the spring and summer for a minimum of 2 consecutive years preceding study participation. Presence or absence of hypomania during nonwinter months was not used as a criterion for selection. At the time of the studies, usually during the winter, subjects had to be free of psychotropic medication. Because the research protocols were challenging, subjects were selected who would comply with research demands, such as coming to the hospital regularly. Thus, the subject group was composed of mature patients who may not have

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represented a random sample of persons who suffer from winter depression, but who were. similar to patients studied by other investigators. The mean age of the subjects was 42.2 + 11.4 years (SD), with a range of 20 to 70 years. Fifty-one of the subjects were female and 10 were male. This is similar to the sex ratio found in other investigators’ studies.

Instruments Primary diagnoses. All 61 patients were administered the SADS-L to achieve RDC for primary and secondary diagnoses of psychiatric illness. The SADS-L, a standardized interview instrument, was administered to individual patients by a psychiatrist or clinical psychologist. In addition, 51 patients completed the General Behavior Inventory (GBI) during the winter months.” The GBI is a self-report inventory designed to assess features of bipolar and unipolar illness, and has been used to identify bipolar, An advantage of the GBI is that it cyclothymic, and unipolar patients with a high degree of accuracy. 22~23 assesses a large number of affect-related behaviors and descriptors of mood, and appears to be able to discriminate between unipolar and bipolar conditions regardless of the patient’s mood state at the time of testing. A two-dimensional scoring system is used for the GBI in which each patient receives a total score on the depression items and total score on the biphasic (hypomanic plus mood variability) items. Cutoff scores for diagnostic classification may be relatively high (to establish rigorous diagnostic criteria) or low (to maximize sensitivity to the presence of disorders). After reviewing the literature on the GBI, two sets of cutoff scores were adopted that have been used by the developers of the instrument to assess different patient groups with affective disorders.2’-25 High cutoff scores were set with a unipolar diagnosis occurring with a depression score above 22 and a biphasic score less than 17; bipolar diagnosis was set with a depression score above 22 and a biphasic score above 16. Low cutoff scores were set with a unipolar diagnosis occurring with a depression score greater than 21 and a biphasic score below 12; bipolar diagnosis with a depression score greater than 21 and a biphasic score greater than 11. Fifty of the subjects completed the Minnesota Multiphasic Changes in hypomanic symptoms. Personality Inventory (MMPI) during the winter before treatment and in the summer following light treatment.26 In all cases, at least 2 months had elapsed between the summer administration of the MMPI and discontinuation of light treatment. Scores on the Mania (Ma) and Hypomania (HYP) scales were examined for evidence of bipolar illness.” Data from the 61 subjects on family history and past Family history and psychiatric treatment. psychiatric treatment were obtained by clinical interview and a screening questionnaire.*s Symptoms of winter depression. To assess the nature of winter depression symptoms, a questionnaire was developed that listed symptoms of this disorder that have been described in the literature or by patients in Oregon. Symptoms were rated using a four-point Likert scale both according to intensity (i.e., symptoms considered [ 11, no problem to [4], severe problem) and frequency (i.e., symptoms occurred [ 11, once per month or less to [4], almost every day). To find out if these symptoms occurred only during the winter, subjects were asked to rate how troublesome they found these same symptoms during the summer. In addition, to determine if some symptoms of winter depression are common to the general population in winter, the same questionnaire was completed by 47 control subjects. Control subjects were age-matched employees of the Oregon Health Science University without a history of depression during the winter. The mean age of the control subjects was 41.5 + 13.8 years, with a range of 22 to 78 years. Forty-two of the controls were female and five were male.

RESULTS

SADS-L/RDC

Diagnoses

Using the SADS-L, the majority of the subjects (n = 54, 88%) met RDC for major depressive syndrome (Table 2). Only five subjects (8%) met RDC for bipolar I or II disorders. In addition to their diagnoses of affective disorder, a number of subjects had a significant history of past psychiatric problems. These subjects met RDC for past alcohol use disorder (13%), generalized anxiety disorder (18%), panic disorder (7%), phobic disorder (3%), or paranoid personality disorder (2%).

IS WINTER

199

DEPRESSION A BIPOLAR DISORDER?

Table 2. Type of Affective Disorder of Winter Depressive Patients Using SADS-L/RDC Criteria in = 61) Type of Affective Disorder

No. of Patients

Percent

Major depressive syndrome Minor depressive syndrome Bipolar I disorder Bipolar II disorder Did not meet criteria for diagnosis

54 1 1 4 1

88.5 1.5 1.5 7 1.5

General Behavior Inventory Using high cutoff scores to establish rigorous criteria for diagnoses, only 25 subjects (42%) had affective symptoms that met criteria for unipolar or bipolar disorder. Of these subjects, 20 (40%) were classified as having a unipolar disorder. One subject, the only one with an RDC diagnosis of bipolar I disorder, was correctly classified by the GBI as having a bipolar disorder. None met RDC for bipolar II disorder. Using low cutoff scores to maximize diagnostic sensitivity, only half of the subjects (n = 25, 50%) were classified as having a unipolar or bipolar disorder. Seventeen subjects (34%) were classified as having unipolar disorders and eight (16%) were classified as having bipolar disorders. Among the five subjects who met RDC for bipolar I or II disorder, four also were identified by the GBI as having bipolar disorders. Combining RDC and GBI criteria, nine subjects at most were diagnosed as having bipolar conditions. MMPI Scores Among the 50 subjects twice administered the MMPI, there were significant changes (t = 6.297, df = 49, P < .OOl) on the Depression (D) scale. The mean T score dropped from 7 1.O f 14.8 (SD) during winter to 58.4 k 13.2 (SD) in summer. Changes on the Ma scale from winter (Ma = 52.1 + 9.4) to summer (Ma = 50.9 + 11.0) were nonsignificant (t = 1.238, df = 49, P = .20). On the HYP scale, subjects showed a significant decrease (t = 2.451, df = 49, P = .02) from winter (Ma = 50.1 + 7.5) to summer (Ma = 48.0 f 9.1). However, while this change is statistically significant, both means are in the normal range. Individual profiles were examined to determine if some subjects had significant summer elevations on the Ma or HYP scales. A T score of 70 was established as the criterion for clinical significance. 2gOne subject obtained a T score above 70 (T score of 72) on the Ma scale during the summer, but no subjects obtained T scores this high on the HYP scale in the summer. Overall, data from the MMPI were not suggestive of mania or hypomania among the patients during the summer. Family History Among the 61 patients, only four (7%) reported having a family member (i.e., parent, grandparent or sibling) who suffered from manic-depressive illness, four (7%) reported having a family member diagnosed with schizophrenia, and three (5%) reported having a family member who had committed suicide. Twenty-seven of the patients (44%) reported having a family member with a history of nonseasonal depressive illness, and 16 (26%) reported having a family member who

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experienced a seasonal pattern of depression similar to their own. In addition, 22 patients (36%) reported having a family member with a significant history of alcohol abuse. Among the patient group, 40 (66%) reported having a family member who suffered from nonseasonal depression, winter depression or alcohol abuse. It was difficult to assess incidence of psychiatric problems among patients’ children because many were still young and might not manifest symptoms until a later age. Of the 36 patients with children, none reported having a child with manic-depressive illness. Four (11%) reported having at least one child with nonseasonal depressive illness and six (17%) reported having at least one child with a seasonal pattern of depression.

Treatment History Most of the patients (n = 41, 67%) had been treated in psychotherapy and over one-third (n = 22, 38%) had been treated with antidepressant medication, with many (n = 19, 31%) reporting the use of tricyclic antidepressants, but fewer (n = 3, 7%) reporting the use of monoamine oxidase (MAO) inhibitors. Most patients (n = 4 1,67%) reported use of tranquilizers, with nearly one-third (n = 19, 31%) reporting past use of minor tranquilizers. Fewer patients (n = 6, 10%) reported the use of major tranquilizers. A history of inpatient hospitalizations was reported by eight patients (13%). However, only two patients reported a history of electroconvulsive therapy (ECT) (3%). Few of the patients (n = 7, 11%) had been treated with lithium. Among the nine patients diagnosed as bipolar by RDC or GBI criteria, only two had been prescribed lithium in the past.

Common Symptoms of Winter Depression Symptoms of winter depression were rated by patients in terms of intensity and frequency. The symptoms are listed in rank order from most troublesome to least troublesome in Table 3. The most intense and frequent symptom of winter depression among the subjects was a general lack of energy. Almost all of the Table 3. Symptoms of Winter Depression Ranked in Order From Most Troublesome to Least Troublesome h = 60)

1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16.

Lackof energy Sadness Social withdrawal Need for more sleep Difficulty staying awake in the morning Low self-esteem Difficulty coping with ordinary stress Apathy Anhedonia Difficulty making decisions Concentration problems Weight gain Difficulty staying awake in the evening Lack of productivity at work Relationship problems Losing temper easily

*Rated only by women who menstruated.

17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. 30. 31. 32.

Increased appetite Anxiety Irritability Memory problems Difficulty staying awake midday Difficulty staying warm Restless sleep Making mistakes at work Decreased libido Headaches Feeling physically ill Crying spells Periods of unreasonable fear Difficulty falling asleep Premenstrual syndrome* Suicidal thoughts

IS WINTER

DEPRESSION A BIPOLAR DISORDER?

201

subjects reported being bothered by chronic fatigue during the winter months. Subjects ranked feelings of sadness second, and the intensity and frequency of sadness was more variable than fatigue. While many subjects experienced intense periods of dysphoria during the winter, several experienced little sadness and mainly were troubled by lack of energy. Social withdrawal was ranked third and was a common problem with many subjects reporting that they simply wished to “hibernate” in winter. In addition, most subjects reported needing more sleep in the winter and having significant problems staying awake in the morning. Subjects tended to be bothered more by certain somatic features (e.g. weight gain) than many of the common symptoms of dysphoria (e.g. crying spells, suicidal thoughts). Patients’ winter ratings were compared with those of control subjects. In all cases, including somatic symptoms not obviously associated with depression, the normal controls had mean scores indicating that the problems were infrequent and mild, if present at all. Patients’ ratings of winter depression symptoms were significantly higher than normal control subjects’ ratings for all symptoms using Student’s t tests, df = 95. COMMENT

Among 61 winter depressive patients treated at the Oregon Health Sciences University over a 3-year period, the majority did not appear to have bipolar illness. Using SADS-L/RDC and Genera1 Behavior Criteria, nine patients (15%) were diagnosed as having a bipolar I or bipolar II disorder. Few patients reported a family history of manic-depressive illness or had been treated with lithium. Of the 50 subjects who completed the MMPI during the summer following treatment, only one showed a clinical elevation on the scales measuring symptoms of mania and hypomania. While the majority of patients did not meet criteria for diagnosis of bipolar disorder, their symptom patterns and psychiatric histories were in some ways atypical of patients with recurrent unipolar depression. On the GBI most of the patients were not classified as having a unipolar disorder. The most troublesome symptom for the majority of the patients was chronic fatigue. Increased need for sleep, difficulty staying awake in the morning and weight gain were among the most common problems experienced by the patients. A number of symptoms typical of major depression, including decreased libido, crying spells, and suicidal thoughts’*30 were less common among winter depressives. The symptom patterns of the 61 patients were in many ways unlike those of patients with recurrent unipolar depression, which is consistent with other studies of winter depression. Mueller and Allen found that among their winter depressive patients the most significant symptom was fatigue, and labeled the syndrome “Seasonal Energy Disorder.“31 In a study of children with winter depression, Rosenthal et al. asked parents to rank their childrens’ symptoms in order of severity. 32 Irritability and fatigue were ranked as more severe than symptoms of sadness. According to theory,33-35 circadian rhythms of endogenous depressives should be phase-advanced during periods of depression (early morning awakening, advanced onset of minimum core body temperature, and reduced rapid eye movement [REM] 1atency).36 In contrast, winter depressives tend to have phasedelayed circadian rhythms. 37 During winter they show hypersomnia, delayed onset

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of nighttime melatonin production, and normal or delayed REM latency.2V38 Furthermore, winter depressive patients do not show an abnormal response to the dexamethasone suppression test, which is characteristic of many endogenous depressives. 39 Also, winter depressives do not seem to respond as well to tricyclic antidepressants.2 They tend to have hyperphagia, gain weight, and crave carbohydrates in the winter. In some respects, they resemble atypical endogenous depressives. In this study of winter depressive patients, the majority were found not to have a bipolar disorder. This contrasts with other studies that found a high incidence of bipolar illness among winter depressives, which may reflect differences in the diagnostic criteria for hypomania and hyperthymia, as well as in the patient populations selected for treatment. When winter depression (or SAD) was recognized as an affective disorder, preliminary studies suggested that patients with this condition generally had a bipolar disorder. At this point, evidence suggests that the majority of winter depressive patients do not fit neatly into either a bipolar or unipolar classification. In terms of practical considerations, results of this study indicate that winter depression may present in a number of forms. Often, the winter depressive patient will seek consultation from a general physician for symptoms of fatigue rather than ask for psychiatric treatment. A number of Oregon winter depressive patients reported that they first sought medical evaluation for persistent tiredness, suspecting causes such as low blood sugar or anemia; they were found to be physically healthy. Many of the patients in this study had experienced periods of generalized anxiety or had abused alcohol in the past, and a family history of alcohol abuse was common. In treating patients with anxiety or alcohol problems, it could prove useful to assess whether such problem behaviors are related to seasonal patterns. In addition, review of clinical histories indicated that most had sought professional treatment for depression or other psychiatric problems before entering light therapy programs. Common treatments were psychotherapy and antidepressant medications, which usually did not work until springtime. A history of unsuccessful previous treatment may indicate that the patient had winter depression that was not correctly diagnosed. A few winter depressive patients clearly have a bipolar disorder. When patients are treated for depression in the winter, it is important to assess for a history of previous episodes of mania or hypomania. However, depressed bipolar II patients may not be able to provide a convincing history of previous hypomanic episodes. Therefore, clinicians treating winter depressives should alert patients to watch for symptoms of hypomania and maintain contact with them during the spring and summer following treatment. However, evidence of light-induced mania or hypomania is low compared with drug-induced cases. The relationship between bipolar illness and seasonal changes needs to be further investigated. Studies of hospital records of patients with bipolar I illness in England, Wales, Greece, and Australia indicate that mania occurs most often during the spring and summer and least often in the winter. 4’-43 Recently, Akiskal, working with bipolar II patients in Tennessee, reported that most of these patients became depressed in the fall and winter and experienced hypomania in the spring and summer. 44To study the r elationship between bipolar illness and winter depression in

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203

the future, it may prove more useful to begin by focusing on a selected group of bipolar patients rather than studying a general population of winter depressives, few of whom seem to have bipolar illness. REFERENCES 1. American Psychiatric Association: Diagnostic and Statistical Manual of Mental Disorders (ed 3, Revised). Washington, DC, APA, 1987, p 230 2. Rosenthal NE, Sack DA, Gillin JC, et al: Seasonal affective disorder: A description of the syndrome and preliminary findings with light therapy. Arch Gen Psychiatry 142:162-170,1984 3. Lewy AJ, Kern HA, Rosenthal NE, et al: Bright artificial light treatment of a manic-depressive patient with seasonal mood cycle. Am J Psychiatry 139:1496-1498, 1982 4. Spitzer RL, Endicott J, Robins E: Research diagnostic criteria. Arch Gen Psychiatry 35:773-782, 1978 5. Rosenthal NE: Letter to the editor. Arch Gen Psychiatry 43:188-189, 1986 6. Thompson C, Issacs G: Seasonal affective disorder-A British sample: Symptomatology in relation to mode of referral and diagnostic subtype. J Affective Disord 14:1- 11, 1988 7. Wirz-Justice A, Bucheli C, Graw P, et al: Light treatment of seasonal affective disorder in Switzerland. Acta Psychiatr Stand 74:193-204, 1986 8. Thase ME, Kupfer DJ, Negri JM, et al: Significance of fall/winter depression. Washington, DC, Annual Meeting of the American Psychiatric Association, May 1986 9. Yerevanian BI, Anderson JL, Grota LJ, et al: Effects of bright incandescent light on seasonal and nonseasonal major depressive disorder. Psychiatry Res 18:355-364, 1986 10. Akiskal HS: The bipolar spectrum: New concepts in classification and diagnosis, in Greenspoon L (ed): Psychiatry Update: The American Psychiatric Association Annual Review, vol II. Washington, DC, American Psychiatric Press, 1983, pp 271-292 11. Spitzer RL, Endicott J: Schedule for Affective Disorders and Schizophrenia-Lifetime Version. New York, NY, New York State Psychiatric Institute, 1979 12. Endicott J, Spitzer RL: A diagnostic interview: The schedule for affective disorders and schizophrenia. Toronto, Canada, Annual Meeting of the American Psychiatric Association, May 1977 13. Dunner DL, Russek FD, Russek B, et al: Classification of bipolar affective disorder subtypes. Compr Psychiatry 23:186-189, 1982 14. Gershon ES, Hamovit J, Guroff JJ, et al: A family study of schizoaffective, bipolar I, bipolar II, unipolar, and normal control probands. Arch Gen Psychiatry 39:1157-l 167, 1982 15. Dunner DL, Go RCP, Fieve RK: A family study of patients with bipolar II illness. Jerusalem, Israel, 13th CINP Congress, June 1982 16. Coryell W, Endicott J, Reisch T, et al: A family study of bipolar II disorder. Br J Psychiatry 39:1157-1167, 1982 17. Coryell W: Outcome and family studies of bipolar II depression. Psychiatric Ann 17:28-3 1, 1987 18. Fieve RR, Kumbaraci T, Dunner DL: Lithium prophylaxis of depression in bipolar I, bipolar II, and unipolar patients. Am J Psychiatry 133:924-929, 1976 19. Dunner DL, Fieve RR: Clinical features in lithium carbonate prophylaxis failure. Arch Gen Psychiatry 30:229, 1974 20. Dunner DL, Stallone F, Fieve RR: Prophylaxis with lithium carbonate: An update. Arch Gen Psychiatry 39:1344-1345, 1982 21. Depue RA, Slater JF, Wolfstetter-Kansch H, et al: A behavioral paradigm for identifying persons at risk for bipolar depressive disorder: A conceptual framework and five validation studies. J Abnorm Psycho1 90~381-437.1981 22. Depue RA, Keiman RM, Davis P, et al: The behavioral high-risk paradigm and bipolar disorder, VIII: Serum free cortisol in nonpatient cyclothymic subjects selected by the General Behavior Inventory. Am JPsychiatry 142:177-188, 1985 23. Klein DN, Depue RA, Slater JF: Inventory identification of cyclothymia. Arch Gen Psychiatry 43:444-445, 1986 24. Depue RA, Krauss S, Spoont MR, et al: General behavior inventory identification of unipolar and bipolar affective conditions in a nonclinical university population. J Abnorm Psycho1 98:117-126, 1989 25. Klein DN, Dickstein S, Taylor EB, et al: Identifying chronic affective disorders in outpatients: Validation of the General Behavior Inventory. J Clin Consult Psycho1 57:106-l 11, 1989

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26. Hathaway SR, McKinley JC: A multiphasic personality schedule: Construction of the schedule. J Psycho1 10:249-254, 1940 27. Wiggins JS: Content dimensions in the MMPI, in Butcher JN (ed): MMPI: Research Developments and Clinical Applications. New York, NY, McGraw Hill, 1969, pp 45-62 28. Rosenthal NE, Bradt G: Seasonal pattern assessment questionnaire. 1983, unpublished questionnaire 29. Graham J: The MMPI: A Practical Guide. New York, NY, Oxford University, 1977 30. Hamilton M: Symptoms and assessment of depression, in Paykel ES (ed): Handbook of Affective Disorders. New York, NY, Guilford, 1982, pp 3-11 31. Mueller PS, Allen GN: Diagnosis and treatment of severe light-sensitive seasonal energy syndrome (SES) and its relationship to melatonin anabolism. Fairoaks Hospital Psychiatry Letter, 2, 1984 32. Rosenthal NE, Carpenter CJ, James SP, et al: Seasonal affective disorder in children and adolescents. Am J Psychiatry 143:356-358, 1986 33. Papousek M: Chronobiological aspects of cyclothymia. Fortschr Neurol Psychiatr 43:381-440, 1975 34. Kripke DF, Mullaney ML, Atkinson ML, et al: Circadian rhythm disorders in manic-depressives. Biol Psychiatry 13:335-351, 1978 35. Wehr TA, Wirz-Justice A, Goodwin FK, et al: Phase advance of the circadian sleep-wake cycle as an antidepressant. Science 206:710-713, 1979 36. Kripke DF: Phase-advance theories for affective illness, in Wehr TA, Goodwin FL (eds): Circadian Rhythms in Psychiatry, vol I. Pacific Grove, CA, Boxwood, 1983, pp 41-70 37. Lewy AJ, Sack RL, Miller LS, et al: Antidepressant and circadian phase-shifting effects of light. Science 235:352-354, 1987 38. Lewy AJ, Sack RL, Miller LS, et al: Superiority of a.m. light in treating winter depression. Washington, DC, Annual Meeting of the American Psychiatric Association, May 1986 39. James SP, Wehr TA, Sack DA, et al: The dexamethasone suppression test in seasonal affective disorder. Compr Psychiatry 27:224-226, 1986 40. Symonds RL, Williams P: Seasonal variation in the incidence of mania. Br J Psychiatry 129:45-48, 1976 41. Walter SD: Seasonality of mania: A reassessment. Br J Psychiatry 131:345-350, 1977 42. Frangos E, Athanassenas G, Tsitourides S, et al: Seasonality of the episodes of recurrent affective psychoses. J Affective Disord 2:239-237, 1980 43. Parker G, Walter G: Seasonal variation in depressive disorders and suicidal deaths in New South Wales. Br J Psychiatry 140:635-637, 1982 44. Akiskal HS: Bipolar II: Psychopathology and seasonality. Washington, DC, Annual Meeting of the American Psychiatric Association, May 1986