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The theoretical underpinnings of affective temperaments: implications for evolutionary foundations of bipolar disorder and human nature
Journal of Affective Disorders 85 (2005) 231 – 239 www.elsevier.com/locate/jad
Special article
The theoretical underpinnings of affective temperaments: implications for evolutionary foundations of bipolar disorder and human nature Kareen K. Akiskala, Hagop S. Akiskala,b,* a International Mood Center, La Jolla, CA, USA University of California at San Diego and VA Psychiatry Service, San Diego, CA, USA
b
Received 26 April 2004; accepted 16 August 2004
Abstract We sketch out putative evolutionary roles for affective temperaments within the theoretical framework of mood disorders conceptualized as extremes in an oligogenic model of inheritance, whereby the constituent traits in their dilute phenotypes confer adaptive advantages to individuals and/or their social group. Depressive traits, among other functions, would subserve sensitivity to the suffering of other members of the species, overlapping with those of the generalized anxious temperament, thereby enhancing the survival of not only kin but also other conspecifics. The pursuit of romantic opportunities in cyclothymia suggests that it may have evolved as a mechanism in reproductive success; cyclothymics’ creative bent in poetry, music, painting, cooking or fashion design (among men, in particular) also appears useful for sexual seduction. Hyperthymic traits would lend distinct advantages in leadership, exploration, territoriality and mating. These are just some of the possibilities of the rich and complex temperamental traits subserving bipolarity within an evolutionary framework. We test selected aspects of these hypotheses with the use of correlations between the constituent traits of the Temperament Evaluation of Memphis, Pisa, Paris and San Diego (TEMPS) and correlations between the TEMPS and the Temperament and Character Inventory (TCI). Such data support the counterbalancing protective influence of harm avoidance on the risk-taking behavior of cyclothymic individuals, in both men and women. Finally, we outline a hypothesis on the evolutionary function of anxious-depressive traits for women. D 2004 Elsevier B.V. All rights reserved. Keywords: Hyperthymic traits; TEMPS; TCI
1. Introduction
* Corresponding author. Tel.: +1 619 552 8585x2666; fax: +1 619 534 8598. E-mail address: [email protected] (H.S. Akiskal). 0165-0327/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jad.2004.08.002
An evolutionary perspective is not ordinarily part of the thinking repertoire of a psychiatrist when faced with a mentally ill patient. The same can generally be said of clinical psychologists. Nonetheless, such an
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approach has been developing on the sidelines of psychiatry and clinical psychology (Stevens and Price, 2000; Gilbert and Bailey, 2000; Benjamin, 2002; Buss, 2003) with potentially very important contributions to understanding why mental disorders exist in the first place. Unfortunately, while promising, Darwinian medicine (Williams and Nesse, 1991) and psychiatry (McGuire and Troisi, 1998) are fraught with methodological difficulties. Unlike the record of somatically transmitted traits, there is virtually nothing about the behavior of our species before prehistoric times to serve as objective data on which to build rational evolutionary explanations. Although a great deal can be gleaned from the behavior of other animals, a field which is known as ethology (Kramer and McKinney, 1979), mental disorders are far more complex than the aberrant behavior of subhuman primates and mammals. Such a perspective is nonetheless fundamental to psychiatry as a behavioral science (McGuire et al., 1992). For this reason, we believe that the bend of the beginningQ of the Darwinian perspective on mental disorders (Akiskal, 2003) should attempt ingenious methods of validation (Nesse, 1984). This report attempts to sketch out a theoretical perspective, and emerging data-based attempts to validate it, stemming from our work on temperament (Akiskal et al., 1979; Akiskal and Akiskal, 1992; Akiskal, 1996).
2. A theoretical framework It is easy to understand how handicapping anxiety and phobic disorders can be conceptualized as extremes of behaviors necessary for survival (Nesse, 1998). Freud (1894/1917) expressed this concept as follows: bThe expectation that every neurotic phenomenon can be cured may be derived from the belief that the neuroses are something quite unnecessary. . . whereas they are constitutionally fixed illnesses [that] persist over long periods or throughout life.Q We submit that putative traits underlying those for bipolar disorders (Wilson, 1998) likewise represent an excellent paradigm to conceptualize the link between mental disorders and adaptive temperamental attributes. Temperament refers to temporally stable behavior traits with strong affective reactivity.
Current evidence suggests that bipolarity lies along a continuum from extreme temperament to fullblown affective illness (Akiskal et al., 1985; Akiskal and Akiskal, 1988; Akiskal, 2002a,b). Less work has been conducted on the continuum between normal and extreme temperaments (Placidi et al., 1998), but the data available (reviewed in this issue, Akiskal et al., 2005a,b,c), does suggest that many, although not all, temperamental traits tend to be continuously distributed. Although the link between temperament and mental disorder goes back to the earliest days of psychological medicine in the Greek period (Klibansky et al., 1996), it is not presently part of the orthodox body of psychological and psychiatric science (Akiskal et al., 2005a,b,c). Nonetheless, many authorities have hypothesized a continuum between cyclothymia and full-blown manic-depressive illness. The German psychiatrist Kretschmer (1936) expressed it most eloquently when he stated that bendogenous psychoses are nothing but exaggerated forms of normal temperament.Q The British psychiatrist CrichtonMiller (1930) put it tersely thus: bThe term manicdepressive psychosis may be correct enough for use in mental hospitals. . . the term cyclothymia, on the other hand. . . includes all the milder manifestations, and brings the whole syndrome within the frontiers of everyday life.Q Within this theoretical framework, we submit that affective temperaments play a fundamental role in the predisposition to affective disorders and affective psychoses (Akiskal and Akiskal, 1992). Those who question this view may inquire why bnormalQ or bsupernormalQ traits should underlie major mental aberrations. The question could be more meaningfully examined from the reverse position. We submit that the affective temperaments represent the most prevalent phenotypic expression of the genes underlying bipolar disorder: The disorder itself is the aberration (Akiskal, 2002a,b), and exists because the genes themselves, likely to conform to oligogenic models (Akiskal et al., 2000; Kelsoe, 2003), are useful towards evolutionary ends, and, in principle, some of them should be demonstrable in other species. If this model is correct, then adaptive traits must be more common among the bdiluteQ forms of the illness (i.e., bipolar II vs. bipolar I) or among the bclinically wellQ biological relatives who carry some but not all
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of the genes of the mentally ill proband. Indeed, in a previous report by us (Akiskal and Akiskal, 1988), we found that artistic creativity was present in 8% of bipolar II or III vs. a negligible rate in bipolar I, schizoaffective, and unipolar depressive patients; the cyclothymic temperament in soft bipolar patients appeared to mediate such creativity. In addition, Coryell et al. (1989) and Richards et al. (1988) demonstrated far greater achievement in the families as opposed to the identified bipolar patients. The same appears true for social and economic class (Verdoux and Bourgeois, 1995a,b). More broadly, an evolutionary bclass hypothesisQ for several temperaments can be formulated with the following postulates: ! !
!
! !
anxious worrying temperamentally might subserve an altruistic role (Akiskal, 1998); a phobic-anxious temperament in fostering dependence could favor the conjugal bond (Akiskal, 1998); the depressive or melancholic temperament might promote work-orientation in men (Akiskal, 1993) and the marital bond in women (Akiskal, 1998); the cyclothymic temperament is involved in romance and creativity (Akiskal and Akiskal, 1988), the hyperthymic temperament subserves exploration, territoriality and leadership (Akiskal and Akiskal, 1988).
Indeed, affective disorders in their subthreshold traits seem to subserve key roles in emotional communication and survival (Akiskal, 2000). In what follows, we review and report psychometric data in support for several of these hypotheses. This has been possible because, in our original formulation and operationalization of affective temperaments (Akiskal, 1992a, Akiskal et al., 2005a,b, this issue), we included adaptive traits—social phenotypes—relevant for each of the temperaments. Moreover, in establishing the psychometric properties and the external validity of the affective temperaments (Akiskal et al., 2005b, this issue), we examined the correlations of our Temperament Evaluation of Memphis, Pisa, Paris and San Diego (TEMPS)-A instrument (Akiskal et al., 2005b, this issue) with the Cloninger Temperament and Character Inventory (TCI) instrument (1994) which has ethologically
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relevant factors such as bharm avoidanceQ and bnovelty seeking.Q
3. Evolutionary significance of affective temperaments 3.1. The hyperthymic temperament An ethological hypothesis can be supported in the most straightforward fashion for the hyperthymic temperament. Building on classical sources (Kraepelin, 1921; Schneider, 1958) and contemporary observations (Akiskal et al., 1977, 1979), this temperament has been characterized by exuberant, upbeat, overenergetic and overconfident lifelong traits (Akiskal and Akiskal, 1992; Akiskal, 1992a,b): (1) cheerful and overoptimistic; (2) warm, people-seeking, and extroverted; (3) eloquent and jocular; (4) overconfident and self-assured; (5) high energy level, full of plans and improvident activities; (6) over-involved and meddlesome; (7) uninhibited, stimulus-seeking or promiscuous; and (8) habitual short sleeper. Obviously, such traits have great relevance to territoriality and leadership, defending the territory from challenges from within and without the social group. Other authors have also described this trait behavioral pattern. For instance, Possl and von Zerssen (1990) described the biography of these individuals in the following traits: (1) vivid, active, and extroverted; (2) verbally aggressive, self assured; (3) strong-willed; (4) self-employed; (5) risk-taking and sensation-seeking; (6) breaking social norms; and (7) generous and spendthrift. This contribution came from a study of the premorbid behavior of bipolar patients. Gardner (1982), based on a more intuitive formulation, described the behavior of these individuals in even more territorial terms: (1) cheerfulness and joking; (2) irrepressible infectious quality; (3) unusual warmth; (4) expansive; (5) increased self-confidence; (6) scheming; (7) robust and tireless; and (8) pushy and meddlesome. We have developed an operational definition of this temperament (Akiskal et al., 1979; Akiskal and Akiskal, 1992) and studied it in a self-rated form (21 items). In a paper in this issue (Akiskal et al., 2005b), we have reported the emergence of a
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distinct hyperthymic factor from our analysis of 110 items representing five proposed temperaments. It is noteworthy that aspects most relevant to territoriality and leadership had the highest loadings on this factor, including bI am the kind of person who likes to be the bossQ (Table 1). The fact that, in a factor analysis of the affective temperaments, the hyperthymic and depressive temperaments have near mirror image opposite loadings ( 0.93 and +0.78, respectively, [Akiskal et al., 1998]) is consistent with the negative correlation of the hyperthymic temperament with bharm avoidanceQ ( 0.53); coupled with its positive correlation with bnovelty seekingQ (+0.34), indicates that this temperament is always on the go. The latter correlations with the TCI framework (Cloninger et al., 1994) are reported in greater detail elsewhere in this issue (Akiskal et al., 2005b); a summary is given in Table 2. They are reinforced by yet another paper in this issue validating the interview version of the TEMPS against the TCI (Maremmani et al., 2005), showing strong positive correlations between the hyperthymic and the TCI subdimensions of gregariousness, exploratory excitability, uninhibited optimism, attachment, confidence, extravagance, independence, vigor and impulsiveness. Despite their tremendous assets, the hyperthymics’ negative correlation with harm avoidance, nonetheless, render such individuals vulnerable to risks inherent in impulsive action.
Summarized from Akiskal et al. (2005b, this issue).
Novelty seeking Harm avoidance a b c d e f
0.10 0.58
Cycc 0.35 0.49
Hypd 0.34 0.53
Irre 0.26 0.32
Anxf 0.14 0.48
Summarized from Akiskal et al. (2005b, this issue). Dys=Dysthymic. Cyc=Cyclothymic. Hyp=Hyperthymic. Irr=Irritable. Anx=Generalized anxious.
3.2. The generalized anxious temperament
0.68
0.66 0.63
Table 3 The generalized anxious factora
Factor 4
a
Dysb
An evolutionary role for a generalized anxious temperament can also be envisioned. This temperament, which describes an exaggerated personality disposition toward worrying, can be considered an baltruistic anxietyQ (Akiskal, 1998) subserving, hypothetically the survival of one’s extended phenotype in a kin selection paradigm (Hamilton, 1963). That worrying would increase upon relaxation (Berkovec et al., 1991) is not a paradox, and makes sense in an ethological perspective. It is of great theoretical and practical relevance in our analysis (Akiskal et al., 2005b, this issue) of the 26 traits that constitute this construct in its self-rated form that an independent generalized anxious factor emerged with strong loading on the three items related to worrying about one’s kin (Table 3). In support for the evolutionary perspective proposed herein, and summarized in Table 2, this temperament (Akiskal et al., 2005b, this issue) correlates positively with harm avoidance (+0.48) and negatively with novelty seeking ( 0.14).
Table 1 Validated traits of the hyperthymic temperament in the San Diego TEMPS—A study I have a gift for speech, convincing and inspiring the others I often get many great ideas I love to tackle new projects, even if risky I like telling jokes, people tell me I am humorous I have abilities and expertise in many fields I am totally comfortable even with people I hardly know I love to be with a lot of people I am the kind of person who likes to be the boss
Table 2 Correlation coefficients between temperaments (TEMPS) and personality (TCI)a
Factor 5
0.58 0.57 0.55 0.53 0.48
I am often fearful of someone in my family coming down with a serious disease I’m always thinking someone might break bad news to me about a family member When someone is late coming home, I fear they may have had an accident a
Summarized from Akiskal et al. (2005b, this issue).
0.80
0.72
0.66
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3.3. The depressive temperament
Table 5 Female–male ratio in different types of affective illnessa
The depressive temperament overlaps to some extent with the generalized anxious (Erfurth et al., 2005, this issue). The overlap pertains largely to cognitive attributes. Nonetheless, there are differences in nuance. Sensitivity to suffering, a cardinal feature of the depressive temperament, represents an important attribute in a species like ours, where caring for young and sick individuals is necessary for survival (Akiskal, 2001). This temperament (Table 4), the anlage of dysthymia, in the extreme often leads to clinical (major) depression. These people tend to be self-denying and devote themselves to others: family, institutions, helping professions. They feel in greatest equilibrium when in harmony with others, conforming to social norms and roles (Possl and von Zerssen, 1990; Kraus, 1996; Ueki et al., 2004). This is true for both men and women with this temperament, who are vulnerable to develop clinical depression when divested from such roles. A new study (Akiskal et al. 2005b, this issue) sheds light on their assets and liabilities: the fact that the depressive type correlates positively with harm avoidance (+0.58) and negatively with novelty seeking ( 0.10)—see Table 2—suggests that their search for harmony and security in familiar, social and professional bonds is protective to a point; disincli-
Manic-depressive illness (1:1) Bipolar II (2:1) Recurrent unipolar depression (2:1) Rapid-cycling (3:1) Minor depression (4:1)
Table 4 Validated traits of the depressive temperament in the memphis TEMPS—a studya People tell me I am unable to see the lighter side of things. I have always blamed myself for what others might consider no big deal. I do not seem to have as much energy as other people. I’m the kind of person who does not like change very much. In a group, I would rather hear others talk. I often give in to others. I feel very uneasy meeting new people. My feelings are easily hurt by criticism or rejection. I put the needs of others above my own. I would rather work for someone else than be the boss. a
Akiskal et al. (2005c, this issue), in press.
0.32 0.47 0.31 0.44
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a Tabulated from Boyd and Weissman (1982), Perugi et al. (1990) and Kilzieh and Akiskal (1999).
nation to explore the new would make their lives boring at best and vulnerable to breakdown in situations of loss of the familiar. This type is predominant in females (Placidi et al., 1998; Erfurth et al., 2005, this issue). Hypothetically, such predominance may have considerable evolutionary significance (Niculescu and Akiskal, 2001). In a recent paper, Angst et al. (2004) showed that being married was highly correlated with depression, especially subthreshold depression, and that it was lowest in individuals who had experienced no level of depression. Some view marriage as depressant for women (Gove, 1978), but this author did not properly control for alcoholism in the male, which may have eliminated the gender differences. The depressant hypothesis of marriage for women is contradicted by the inverse relationship between gender ratio and the severity of depression displayed in Table 5. Therefore, trait levels of depression might have a putative evolutionary advantage for women. What might that advantage be? An evolutionary hypothesis would suggest that anxiousdepressive traits promote bonding to a male, as well as protecting the resultant pregnancy and the offspring (Akiskal et al., 2005a,b,c). The harm avoidance data (+correlation) and the novelty seeking data ( correlation) presented above support our bdepression-protectiveQ evolutionary hypothesis for women.
0.44
3.4. The cyclothymic temperament
0.51 0.45 0.42
As of our original study (Akiskal et al., 1977), we have found that bfalling in and out of loveQ is an important characteristic of cyclothymic individuals. Given the topic of love, we thought it appropriate to validate it as a constituent of the cyclothymic trait in our collaborative French study! These data are summarized in Table 6 (Akiskal et al., 2005a). The
0.49 0.45
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Table 6 Traits of the cyclothymic temperament in its French validationa Feeling often tired for no reason Experiencing all emotions intensely Rapid shifts in mood and energy Mood and energy up or down, rarely in between Alternating between feeling high and then low Thinking ability fluctuates greatly Enjoying people and then losing interest Exploding at others then feeling guilty Starting things then losing interest Mood changes without knowing why Alternating between bubbling with energy and sluggish Rapid shifts of spirits Alternating between optimism and pessimism Feeling overly confident and then unsure of oneself Alternating between being sociable and withdrawn Wide variation of sleep need Perceptions vary between vivid and dull Being happy and sad at the same time Prone to daydreaming Strong urge for risky or outrageous behavior Having fallen in and out of love numerous times a
0.25 0.46 0.74 0.68 0.64 0.68 0.58 0.41 0.50 0.60 0.64 0.56 0.56 0.56 0.53 0.57 0.67 0.57 0.42 0.40 0.33
Akiskal et al. (2005a), this issue.
pursuit of lovemaking opportunities is obviously of great ethological significance because ultimately Darwinian evolution works through sexual behavior in transmitting desirable traits. We have hypothesized that the flamboyant and restless pursuit of romantic opportunities in cyclothymia subserves such a mechanism (Akiskal, 2000). Even their creative bent in poetry, music, painting, or fashion design may have evolved to subserve such a mechanism. Moreover, cyclothymic women, with their temperamental bcapriciousnessQ, would make them difficult to attain for lovemaking, thereby increasing the likelihood that the most brobustQ male could be found, leading to a better chance for adaptive survival of offspring emerging from such unions on a protected territory with advantages of nourishment and opportunities. Cyclothymic traits appear to lie on a polygenic continuum between excessive temperament and bipolar disorder. Indeed, clinically identified cyclothymes have patterns of familial affective illness, as one would expect for a forme fruste disorder (Akiskal et al., 1977). Cyclothymia has also been observed in the juvenile offspring of bipolar probands (Akiskal et al., 1995). Hypothetically, this temperament might represent one of the inherited trait diatheses for bipolar disorder. For instance,
moody–temperamental individuals are overrepresented in the bdiscordantQ monozygotic co-twins of bipolar patients (Bertelsen et al., 1977). Alternatively, and in a more theoretical vein, bipolar illness might be the genetic reservoir for the desirable cyclothymic traits in the population at large (Akiskal, 2000). These desirable traits, upheld in our TEMPS-A research (Akiskal et al., 2005a,b,c, this issue) and summarized in Table 2, correlated highly with novelty seeking (+0.49) and curiously positively with harm avoidance as well (+0.35). The latter might be hypothesized to represent a bprotectiveQ break against the dangers of the most extremes of risk-taking.
4. Implications for therapy The foregoing data and considerations have important implications for the treatment of mood disorders, particularly for the treatment of bipolar disorders. Because dilute expressions of the illness may persist between major episodes, baggressive treatmentQ with mood stabilizers can comprise adaptive functioning and what is unique to the patient as a person. Except in the acute phases of the illness, the emphasis in treatment should be more on functioning than complete mood stabilization (Akiskal and Akiskal, 2005, in press). There are also psychotherapeutic implications (Akiskal, 1992b). Generalized anxious temperament can benefit from meditation, a phobic temperament from cognitive behavioral approaches, a dysthymic individual from work as therapy, and the cyclothymic would require rhythmotherapy and limit setting. Hyperthymic individuals are action-oriented rather than psychologically oriented, and typically shun psychiatrists and psychotherapists. They are more interested in running the world than bbeing lectured toQ about the desirability of change of behavior at a time of major conflict. The approach to such individuals in psychotherapy is among the most challenging in our field. The inflexibility of their otherwise adaptive traits is at the root of the sexual and financial scandals and tragedies (Akiskal, 2000) that great men bring upon themselves (this temperament is more prevalent in men [Placidi et al., 1998]).
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5. Concluding remarks We have presented a theoretical Darwinian framework for bipolar illness. In an oligogenic model, the constituent traits of this illness may have emerged for survival and adaptive roles in the evolutionary past of our species. These roles include, among others, exploration, territoriality, leadership, social organization, mate selection, and caring for others. The adaptive role of behavioral traits implicated in human evolution may actually transcend the individual and involve the social group at large (Pepper, 2000; Fletcher and Zwick, 2004). Cloninger (1986, 1987) has suggested that harmavoidant and novelty-seeking reaction patterns arise from multifactorial phylogenetic mechanisms, which, in their boptimaQ, are advantageous to the adaptation and survival of the individual. It is also likely that even in their extreme expression, each reaction or temperament type might confer advantages at times of new environmental challenges; thereby conferring survival advantages to the social group at large. In other words, individual temperamental excesses, while not bidealQ or optimal for a given person who expresses them at a time of challenge, may nonetheless in aggregate with other extreme temperaments serve as boptimaQ for a given society—hence to the evolutionary adaptation of our species at large. If nothing else, this should lead to greater tolerance to human diversity: extreme types may hold the genetic keys to our adaptation in the world we inhabit—the planet we share. Indeed, it has been suggested that human evolution has occurred because of a few people with the requisite adaptability in the face of new environments created by ecological disasters (Potts, 1997). From a therapeutic standpoint, understanding the evolutionary context of human behavior should help the transition away from the concept of personality disorder (with its emphasis on what is negative and malfunctioning in one’s personality domain) to that of temperament (which subsumes both assets and liabilities). Such transition, in turn, should help psychiatry and clinical psychology graduate to a new era in which instead of blaming the patients’ character, mental health professionals will endeavor to teach people how to maximize their personal assets to overcome their disordered interpersonal life.
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In a future contribution, we will pursue the hypothesis that curiosity, novelty-seeking and/or creativity associated with bipolar traits may have played a signal role in the rise of the new humans, including the Homo sapiens, and the extinction of the Neanderthal. Such a hypothesis does not rule out the possibility that social interaction and even mating with the Neanderthal—with their love for the familiar terrain, caring and peaceful attributes—may have contributed to the evolutionary success of the new humans. Some support for these views can be found in the anthropological archaeological record (Mellars, 1995; Wong, 2000; Rigaud and Simek, 2004). More speculatively, the anxious-dysthymic and hyperthymic traits underlying bipolarity may have their origin in the respective mix of Neanderthal and early Homo sapiens or their ancestors; the cyclothymic type might actually reflect a me´lange of the attributes of the two.
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disorders. Presented at Collegium Internationale Neuro-psychopharmacologicum, pp. 20 – 24. Benjamin, L.S., 2002. Interpersonal Diagnosis and Treatment of Personality Disorders. (Second Edition). The Guilford Press, New York. Berkovec, T.D., Shadick, R.N., Hopkins, M., 1991. The nature of normal and pathological worry. In: Rapee, R.M., Barlow, D.H. (Eds.), Chronic Anxiety: Generalized Anxiety Disorder and Mixed Anxiety-Depression. The Guilford Press, New York. Bertelsen, A., Harvald, B., Hauge, M., 1977. A Danish twin study of manic-depressive disorders. Br. J. Psychiatry 130, 330 – 351. Boyd, J.H., Weissman, M.M., 1982. Screening for depression in a community sample. Understanding the discrepancies between depression symptom and diagnostic sales. Arch. Gen. Psychiatry 39, 1195 – 1200. Buss, D.M., 2003. Evolutionary Psychology: The New Science of the Mind. (Second Edition). Pearson Allyn & Bacon. Cloninger, C.R., 1986. A unified biosocial theory of personality and its role in the development of anxiety states. Psychiatr. Dev. 4, 167 – 226. Cloninger, C.R., 1987. A systematic method for clinical description and classification of personality variants. A proposal. Arch. Gen. Psychiatry 44, 573 – 588. Cloninger, R.C., Przybeck, T.R., Svrakic, D.M., et al., 1994. The Temperament and Character Inventory (TCI): A guide to its development and use. Center for Psychobiology of Personality, Washington University, St. Louis, MO. Coryell, W., Endicott, J., Keller, M., 1989. Bipolar affective disorder and high achievement: a familial association. Am. J. Psychiatry 146, 983 – 988. Crichton-Miller, H., 1930. Discussion of the diagnosis and treatment of the milder forms of the manic-depressive psychosis. Proc. R. Soc. Med. 23, 883 – 886. Erfurth, A., Gerlach, A.L., Hellweg, I., Boenigk, I., Michael, N., Akiskal, H.S., 2005. Studies on a German (Munster) version of the temperament auto-questionnaire TEMPS-A: construction and validation of the briefTEMPS-M. J. Affect. Disord. 85, 53–70. Fletcher, J.A., Zwick, M., 2004. Strong altruism can evolve in randomly formed groups. J. Theor. Biol. 228, 303 – 313. Freud, S., 1894/1917. The neuropsychoses of defence. In: Strachey, J. (Ed.), Standard Edition of the Complete Psychological Works of Sigmund Freud. Hogarth Press, London. Gardner Jr., R., 1982. Mechanisms in manic-depressive disorder: an evolutionary model. Arch. Gen. Psychiatry 39, 1436 – 1441. Gilbert, P., Bailey, K.G., 2000. Genes on the Couch: Explorations in Evolutionary Psychology. Taylor & Francis Group, London. Gove, W.R., 1978. Sex differences in mental illness among adult men and women: an evaluation of four questions raised regarding the evidence on the higher rates of women. Soc. Sci. Med. 12, 187 – 198. Hamilton, W.D., 1963. The evolution of altruistic behavior. Am. Natur. 97, 534 – 556. Kelsoe, J.R., 2003. Arguments for the genetic basis of the bipolar spectrum. J. Affect. Disord. 73, 183 – 197.
K.K. Akiskal, H.S. Akiskal / Journal of Affective Disorders 85 (2005) 231–239 Kilzieh, N., Akiskal, H.S., 1999. Rapid-cycling bipolar disorder. An overview of research and clinical experience. Psychiatr. Clin. North Am. 22, 585 – 607. Klibansky, R., Panowsky, E., Fritz Saxl, F., 1996. Saturn und Melancholie. University of Chicago Press, Chicago. Kraus, A., 1996. Role performance, identity structure and psychosis in melancholic and manic-depressive patients. In: Mundt, C., Goldstein, M.J., Hahlweg, K., Fiedler, P. (Eds.), Interpersonal Factors in the Origin and Course of Affective Disorders. Royal College of Psychiatrists, London, pp. 31 – 47. Kraepelin, E., 1921. Manic-Depressive Illness and Paranoia. Livingstone, Edinburgh. Kramer, D.A., McKinney Jr., W.T., 1979. The overlapping territories of psychiatry and ethology. J. Nerv. Ment. Dis. 167, 3 – 22. Kretschmer, E., 1936. Physique and Character. Kegan, Paul, Trench, Trubner and Co. Ltd., London. McGuire, M., Troisi, A., 1998. Darwinian Psychiatry. Oxford Univ. Press, New York. McGuire, M.T., Marks, I., Nesse, R.M., Troisi, A., 1992. Evolutionary biology: a basic science for psychiatry? Acta Psychiatr. Scand. 86, 89 – 96. Maremmani, I., Akiskal, H.S., Signoretta, S., Liguori, A., Perugi, G., Cloninger, R., 2005. The relationship of Kraepelian affective temperaments (as measured by TEMPS-I) to the Tridimensional Personality Questionnaire (TPQ). J. Affect. Disord. 85, 17–28. (this issue). Mellars, PA., 1995. The Neanderthal Legacy: An Archaeological Perspective of Western Europe. Princeton Univ. Press, Princeton, NJ. Nesse, R.M., 1984. An evolutionary perspective on psychiatry. Compr. Psychiatry 25, 575 – 580. Nesse, R., 1998. Emotional disorders in evolutionary perspective. Br. J. Med. Psychol. 71, 397 – 415. Niculescu, A.B., Akiskal, H.S., 2001. Sex hormones, darwinism, and depression. Arch. Gen. Psychiatry 58, 183 – 184. Pepper, J.W., 2000. Relatedness in trait group models of social evolution. J. Theor. Biol. 206, 355 – 368. Perugi, G., Musetti, L., Simonini, E., Piagentini, F., Cassano, G.B., Akiskal, H.S., 1990. Gender mediated clinical features of depressive illness: the importance of temperamental differences. Br. J. Psychiatry 157, 835 – 841.
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Placidi, G.F, Signoretta, S., Liguori, A., Gervasi, R., Maremmani, I., Akiskal, H.S., 1998. The semi-structured affective temperament interview (TEMPS-I): reliability and psychometric properties in 1010 14–26 year students. J. Affect. Disord. 47, 1 – 10. Possl, J., von Zerssen, D., 1990. A case history analysis of the bmanic typeQ and the bmelancholic typeQ of premorbid personality in affectively ill patients. Eur. Arch. Psychiatr. Neurol. Sci. 23, 347 – 355. Potts, R., 1997. Humanity’s Descent. The Consequences of Ecological Instability. Avon Books, New York. Richards, R., Kinney, D.K., Lunde, I., Benet, M., Merzel, A.P., 1988. Creativity in manic-depressives, cyclothymes, their normal relatives, and control subjects. J. Abnorm. Psychology 97, 281 – 288. Rigaud, J.-Ph., Simek, J.F., 2004. Milieux, Techniques et Cultures Pre´historiques—La Grotte XVI a` Cenac-et-Saint-Julien, Dordogne. http://www.ipgq.u-bordeaux1.fr/Pages/operations/ grotte16.html, Accessed 07/13/2004. Schneider, K., 1958. Psychopathic Personalities. Charles C. Thomas, Springfield, IL. Stevens, A., Price, J., 2000. Evolutionary Psychiatry: A new beginning, 2nd ed. Routledge, London. Ueki, H., Holzapfel, C., Sakado, K., Washino, K., Inoue, M., Ogawa, N., 2004. Dimension of typus melancholicus on Kasahara’s inventory for the melancholic type personality. Psychopathology 37, 53 – 58. Verdoux, H., Bourgeois, M., 1995a. Comparative study on the occupational levels of unipolar and bipolar probands and relatives. Ann. Med. Psychol. 153, 67 – 70. Verdoux, H., Bourgeois, M., 1995b. Social class in unipolar and bipolar probands and relatives. J. Affect. Disord. 33, 181 – 187. Wong, Kate, 2000/2004. A French site suggests Neanderthals and early modern humans behaved similarly. Scientific American: Paleolithic Pit Stop. http://www.sciam.com/print_version. cfm?article, ID=000F0825-AC71-1C72-9EB7809EC588F2D7 (Accessed 07/13/2004). Williams, G.C., Nesse, R.M., 1991. The dawn of Darwinian medicine. Q. Rev. Biol. 66, 1 – 22. Wilson, D.R., 1998. Evolutionary epidemiology and manic depression. Br. J. Med. Psychol. 71, 375 – 395.
Special article
The theoretical underpinnings of affective temperaments: implications for evolutionary foundations of bipolar disorder and human nature Kareen K. Akiskala, Hagop S. Akiskala,b,* a International Mood Center, La Jolla, CA, USA University of California at San Diego and VA Psychiatry Service, San Diego, CA, USA
b
Received 26 April 2004; accepted 16 August 2004
Abstract We sketch out putative evolutionary roles for affective temperaments within the theoretical framework of mood disorders conceptualized as extremes in an oligogenic model of inheritance, whereby the constituent traits in their dilute phenotypes confer adaptive advantages to individuals and/or their social group. Depressive traits, among other functions, would subserve sensitivity to the suffering of other members of the species, overlapping with those of the generalized anxious temperament, thereby enhancing the survival of not only kin but also other conspecifics. The pursuit of romantic opportunities in cyclothymia suggests that it may have evolved as a mechanism in reproductive success; cyclothymics’ creative bent in poetry, music, painting, cooking or fashion design (among men, in particular) also appears useful for sexual seduction. Hyperthymic traits would lend distinct advantages in leadership, exploration, territoriality and mating. These are just some of the possibilities of the rich and complex temperamental traits subserving bipolarity within an evolutionary framework. We test selected aspects of these hypotheses with the use of correlations between the constituent traits of the Temperament Evaluation of Memphis, Pisa, Paris and San Diego (TEMPS) and correlations between the TEMPS and the Temperament and Character Inventory (TCI). Such data support the counterbalancing protective influence of harm avoidance on the risk-taking behavior of cyclothymic individuals, in both men and women. Finally, we outline a hypothesis on the evolutionary function of anxious-depressive traits for women. D 2004 Elsevier B.V. All rights reserved. Keywords: Hyperthymic traits; TEMPS; TCI
1. Introduction
* Corresponding author. Tel.: +1 619 552 8585x2666; fax: +1 619 534 8598. E-mail address: [email protected] (H.S. Akiskal). 0165-0327/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.jad.2004.08.002
An evolutionary perspective is not ordinarily part of the thinking repertoire of a psychiatrist when faced with a mentally ill patient. The same can generally be said of clinical psychologists. Nonetheless, such an
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approach has been developing on the sidelines of psychiatry and clinical psychology (Stevens and Price, 2000; Gilbert and Bailey, 2000; Benjamin, 2002; Buss, 2003) with potentially very important contributions to understanding why mental disorders exist in the first place. Unfortunately, while promising, Darwinian medicine (Williams and Nesse, 1991) and psychiatry (McGuire and Troisi, 1998) are fraught with methodological difficulties. Unlike the record of somatically transmitted traits, there is virtually nothing about the behavior of our species before prehistoric times to serve as objective data on which to build rational evolutionary explanations. Although a great deal can be gleaned from the behavior of other animals, a field which is known as ethology (Kramer and McKinney, 1979), mental disorders are far more complex than the aberrant behavior of subhuman primates and mammals. Such a perspective is nonetheless fundamental to psychiatry as a behavioral science (McGuire et al., 1992). For this reason, we believe that the bend of the beginningQ of the Darwinian perspective on mental disorders (Akiskal, 2003) should attempt ingenious methods of validation (Nesse, 1984). This report attempts to sketch out a theoretical perspective, and emerging data-based attempts to validate it, stemming from our work on temperament (Akiskal et al., 1979; Akiskal and Akiskal, 1992; Akiskal, 1996).
2. A theoretical framework It is easy to understand how handicapping anxiety and phobic disorders can be conceptualized as extremes of behaviors necessary for survival (Nesse, 1998). Freud (1894/1917) expressed this concept as follows: bThe expectation that every neurotic phenomenon can be cured may be derived from the belief that the neuroses are something quite unnecessary. . . whereas they are constitutionally fixed illnesses [that] persist over long periods or throughout life.Q We submit that putative traits underlying those for bipolar disorders (Wilson, 1998) likewise represent an excellent paradigm to conceptualize the link between mental disorders and adaptive temperamental attributes. Temperament refers to temporally stable behavior traits with strong affective reactivity.
Current evidence suggests that bipolarity lies along a continuum from extreme temperament to fullblown affective illness (Akiskal et al., 1985; Akiskal and Akiskal, 1988; Akiskal, 2002a,b). Less work has been conducted on the continuum between normal and extreme temperaments (Placidi et al., 1998), but the data available (reviewed in this issue, Akiskal et al., 2005a,b,c), does suggest that many, although not all, temperamental traits tend to be continuously distributed. Although the link between temperament and mental disorder goes back to the earliest days of psychological medicine in the Greek period (Klibansky et al., 1996), it is not presently part of the orthodox body of psychological and psychiatric science (Akiskal et al., 2005a,b,c). Nonetheless, many authorities have hypothesized a continuum between cyclothymia and full-blown manic-depressive illness. The German psychiatrist Kretschmer (1936) expressed it most eloquently when he stated that bendogenous psychoses are nothing but exaggerated forms of normal temperament.Q The British psychiatrist CrichtonMiller (1930) put it tersely thus: bThe term manicdepressive psychosis may be correct enough for use in mental hospitals. . . the term cyclothymia, on the other hand. . . includes all the milder manifestations, and brings the whole syndrome within the frontiers of everyday life.Q Within this theoretical framework, we submit that affective temperaments play a fundamental role in the predisposition to affective disorders and affective psychoses (Akiskal and Akiskal, 1992). Those who question this view may inquire why bnormalQ or bsupernormalQ traits should underlie major mental aberrations. The question could be more meaningfully examined from the reverse position. We submit that the affective temperaments represent the most prevalent phenotypic expression of the genes underlying bipolar disorder: The disorder itself is the aberration (Akiskal, 2002a,b), and exists because the genes themselves, likely to conform to oligogenic models (Akiskal et al., 2000; Kelsoe, 2003), are useful towards evolutionary ends, and, in principle, some of them should be demonstrable in other species. If this model is correct, then adaptive traits must be more common among the bdiluteQ forms of the illness (i.e., bipolar II vs. bipolar I) or among the bclinically wellQ biological relatives who carry some but not all
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of the genes of the mentally ill proband. Indeed, in a previous report by us (Akiskal and Akiskal, 1988), we found that artistic creativity was present in 8% of bipolar II or III vs. a negligible rate in bipolar I, schizoaffective, and unipolar depressive patients; the cyclothymic temperament in soft bipolar patients appeared to mediate such creativity. In addition, Coryell et al. (1989) and Richards et al. (1988) demonstrated far greater achievement in the families as opposed to the identified bipolar patients. The same appears true for social and economic class (Verdoux and Bourgeois, 1995a,b). More broadly, an evolutionary bclass hypothesisQ for several temperaments can be formulated with the following postulates: ! !
!
! !
anxious worrying temperamentally might subserve an altruistic role (Akiskal, 1998); a phobic-anxious temperament in fostering dependence could favor the conjugal bond (Akiskal, 1998); the depressive or melancholic temperament might promote work-orientation in men (Akiskal, 1993) and the marital bond in women (Akiskal, 1998); the cyclothymic temperament is involved in romance and creativity (Akiskal and Akiskal, 1988), the hyperthymic temperament subserves exploration, territoriality and leadership (Akiskal and Akiskal, 1988).
Indeed, affective disorders in their subthreshold traits seem to subserve key roles in emotional communication and survival (Akiskal, 2000). In what follows, we review and report psychometric data in support for several of these hypotheses. This has been possible because, in our original formulation and operationalization of affective temperaments (Akiskal, 1992a, Akiskal et al., 2005a,b, this issue), we included adaptive traits—social phenotypes—relevant for each of the temperaments. Moreover, in establishing the psychometric properties and the external validity of the affective temperaments (Akiskal et al., 2005b, this issue), we examined the correlations of our Temperament Evaluation of Memphis, Pisa, Paris and San Diego (TEMPS)-A instrument (Akiskal et al., 2005b, this issue) with the Cloninger Temperament and Character Inventory (TCI) instrument (1994) which has ethologically
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relevant factors such as bharm avoidanceQ and bnovelty seeking.Q
3. Evolutionary significance of affective temperaments 3.1. The hyperthymic temperament An ethological hypothesis can be supported in the most straightforward fashion for the hyperthymic temperament. Building on classical sources (Kraepelin, 1921; Schneider, 1958) and contemporary observations (Akiskal et al., 1977, 1979), this temperament has been characterized by exuberant, upbeat, overenergetic and overconfident lifelong traits (Akiskal and Akiskal, 1992; Akiskal, 1992a,b): (1) cheerful and overoptimistic; (2) warm, people-seeking, and extroverted; (3) eloquent and jocular; (4) overconfident and self-assured; (5) high energy level, full of plans and improvident activities; (6) over-involved and meddlesome; (7) uninhibited, stimulus-seeking or promiscuous; and (8) habitual short sleeper. Obviously, such traits have great relevance to territoriality and leadership, defending the territory from challenges from within and without the social group. Other authors have also described this trait behavioral pattern. For instance, Possl and von Zerssen (1990) described the biography of these individuals in the following traits: (1) vivid, active, and extroverted; (2) verbally aggressive, self assured; (3) strong-willed; (4) self-employed; (5) risk-taking and sensation-seeking; (6) breaking social norms; and (7) generous and spendthrift. This contribution came from a study of the premorbid behavior of bipolar patients. Gardner (1982), based on a more intuitive formulation, described the behavior of these individuals in even more territorial terms: (1) cheerfulness and joking; (2) irrepressible infectious quality; (3) unusual warmth; (4) expansive; (5) increased self-confidence; (6) scheming; (7) robust and tireless; and (8) pushy and meddlesome. We have developed an operational definition of this temperament (Akiskal et al., 1979; Akiskal and Akiskal, 1992) and studied it in a self-rated form (21 items). In a paper in this issue (Akiskal et al., 2005b), we have reported the emergence of a
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distinct hyperthymic factor from our analysis of 110 items representing five proposed temperaments. It is noteworthy that aspects most relevant to territoriality and leadership had the highest loadings on this factor, including bI am the kind of person who likes to be the bossQ (Table 1). The fact that, in a factor analysis of the affective temperaments, the hyperthymic and depressive temperaments have near mirror image opposite loadings ( 0.93 and +0.78, respectively, [Akiskal et al., 1998]) is consistent with the negative correlation of the hyperthymic temperament with bharm avoidanceQ ( 0.53); coupled with its positive correlation with bnovelty seekingQ (+0.34), indicates that this temperament is always on the go. The latter correlations with the TCI framework (Cloninger et al., 1994) are reported in greater detail elsewhere in this issue (Akiskal et al., 2005b); a summary is given in Table 2. They are reinforced by yet another paper in this issue validating the interview version of the TEMPS against the TCI (Maremmani et al., 2005), showing strong positive correlations between the hyperthymic and the TCI subdimensions of gregariousness, exploratory excitability, uninhibited optimism, attachment, confidence, extravagance, independence, vigor and impulsiveness. Despite their tremendous assets, the hyperthymics’ negative correlation with harm avoidance, nonetheless, render such individuals vulnerable to risks inherent in impulsive action.
Summarized from Akiskal et al. (2005b, this issue).
Novelty seeking Harm avoidance a b c d e f
0.10 0.58
Cycc 0.35 0.49
Hypd 0.34 0.53
Irre 0.26 0.32
Anxf 0.14 0.48
Summarized from Akiskal et al. (2005b, this issue). Dys=Dysthymic. Cyc=Cyclothymic. Hyp=Hyperthymic. Irr=Irritable. Anx=Generalized anxious.
3.2. The generalized anxious temperament
0.68
0.66 0.63
Table 3 The generalized anxious factora
Factor 4
a
Dysb
An evolutionary role for a generalized anxious temperament can also be envisioned. This temperament, which describes an exaggerated personality disposition toward worrying, can be considered an baltruistic anxietyQ (Akiskal, 1998) subserving, hypothetically the survival of one’s extended phenotype in a kin selection paradigm (Hamilton, 1963). That worrying would increase upon relaxation (Berkovec et al., 1991) is not a paradox, and makes sense in an ethological perspective. It is of great theoretical and practical relevance in our analysis (Akiskal et al., 2005b, this issue) of the 26 traits that constitute this construct in its self-rated form that an independent generalized anxious factor emerged with strong loading on the three items related to worrying about one’s kin (Table 3). In support for the evolutionary perspective proposed herein, and summarized in Table 2, this temperament (Akiskal et al., 2005b, this issue) correlates positively with harm avoidance (+0.48) and negatively with novelty seeking ( 0.14).
Table 1 Validated traits of the hyperthymic temperament in the San Diego TEMPS—A study I have a gift for speech, convincing and inspiring the others I often get many great ideas I love to tackle new projects, even if risky I like telling jokes, people tell me I am humorous I have abilities and expertise in many fields I am totally comfortable even with people I hardly know I love to be with a lot of people I am the kind of person who likes to be the boss
Table 2 Correlation coefficients between temperaments (TEMPS) and personality (TCI)a
Factor 5
0.58 0.57 0.55 0.53 0.48
I am often fearful of someone in my family coming down with a serious disease I’m always thinking someone might break bad news to me about a family member When someone is late coming home, I fear they may have had an accident a
Summarized from Akiskal et al. (2005b, this issue).
0.80
0.72
0.66
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3.3. The depressive temperament
Table 5 Female–male ratio in different types of affective illnessa
The depressive temperament overlaps to some extent with the generalized anxious (Erfurth et al., 2005, this issue). The overlap pertains largely to cognitive attributes. Nonetheless, there are differences in nuance. Sensitivity to suffering, a cardinal feature of the depressive temperament, represents an important attribute in a species like ours, where caring for young and sick individuals is necessary for survival (Akiskal, 2001). This temperament (Table 4), the anlage of dysthymia, in the extreme often leads to clinical (major) depression. These people tend to be self-denying and devote themselves to others: family, institutions, helping professions. They feel in greatest equilibrium when in harmony with others, conforming to social norms and roles (Possl and von Zerssen, 1990; Kraus, 1996; Ueki et al., 2004). This is true for both men and women with this temperament, who are vulnerable to develop clinical depression when divested from such roles. A new study (Akiskal et al. 2005b, this issue) sheds light on their assets and liabilities: the fact that the depressive type correlates positively with harm avoidance (+0.58) and negatively with novelty seeking ( 0.10)—see Table 2—suggests that their search for harmony and security in familiar, social and professional bonds is protective to a point; disincli-
Manic-depressive illness (1:1) Bipolar II (2:1) Recurrent unipolar depression (2:1) Rapid-cycling (3:1) Minor depression (4:1)
Table 4 Validated traits of the depressive temperament in the memphis TEMPS—a studya People tell me I am unable to see the lighter side of things. I have always blamed myself for what others might consider no big deal. I do not seem to have as much energy as other people. I’m the kind of person who does not like change very much. In a group, I would rather hear others talk. I often give in to others. I feel very uneasy meeting new people. My feelings are easily hurt by criticism or rejection. I put the needs of others above my own. I would rather work for someone else than be the boss. a
Akiskal et al. (2005c, this issue), in press.
0.32 0.47 0.31 0.44
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a Tabulated from Boyd and Weissman (1982), Perugi et al. (1990) and Kilzieh and Akiskal (1999).
nation to explore the new would make their lives boring at best and vulnerable to breakdown in situations of loss of the familiar. This type is predominant in females (Placidi et al., 1998; Erfurth et al., 2005, this issue). Hypothetically, such predominance may have considerable evolutionary significance (Niculescu and Akiskal, 2001). In a recent paper, Angst et al. (2004) showed that being married was highly correlated with depression, especially subthreshold depression, and that it was lowest in individuals who had experienced no level of depression. Some view marriage as depressant for women (Gove, 1978), but this author did not properly control for alcoholism in the male, which may have eliminated the gender differences. The depressant hypothesis of marriage for women is contradicted by the inverse relationship between gender ratio and the severity of depression displayed in Table 5. Therefore, trait levels of depression might have a putative evolutionary advantage for women. What might that advantage be? An evolutionary hypothesis would suggest that anxiousdepressive traits promote bonding to a male, as well as protecting the resultant pregnancy and the offspring (Akiskal et al., 2005a,b,c). The harm avoidance data (+correlation) and the novelty seeking data ( correlation) presented above support our bdepression-protectiveQ evolutionary hypothesis for women.
0.44
3.4. The cyclothymic temperament
0.51 0.45 0.42
As of our original study (Akiskal et al., 1977), we have found that bfalling in and out of loveQ is an important characteristic of cyclothymic individuals. Given the topic of love, we thought it appropriate to validate it as a constituent of the cyclothymic trait in our collaborative French study! These data are summarized in Table 6 (Akiskal et al., 2005a). The
0.49 0.45
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Table 6 Traits of the cyclothymic temperament in its French validationa Feeling often tired for no reason Experiencing all emotions intensely Rapid shifts in mood and energy Mood and energy up or down, rarely in between Alternating between feeling high and then low Thinking ability fluctuates greatly Enjoying people and then losing interest Exploding at others then feeling guilty Starting things then losing interest Mood changes without knowing why Alternating between bubbling with energy and sluggish Rapid shifts of spirits Alternating between optimism and pessimism Feeling overly confident and then unsure of oneself Alternating between being sociable and withdrawn Wide variation of sleep need Perceptions vary between vivid and dull Being happy and sad at the same time Prone to daydreaming Strong urge for risky or outrageous behavior Having fallen in and out of love numerous times a
0.25 0.46 0.74 0.68 0.64 0.68 0.58 0.41 0.50 0.60 0.64 0.56 0.56 0.56 0.53 0.57 0.67 0.57 0.42 0.40 0.33
Akiskal et al. (2005a), this issue.
pursuit of lovemaking opportunities is obviously of great ethological significance because ultimately Darwinian evolution works through sexual behavior in transmitting desirable traits. We have hypothesized that the flamboyant and restless pursuit of romantic opportunities in cyclothymia subserves such a mechanism (Akiskal, 2000). Even their creative bent in poetry, music, painting, or fashion design may have evolved to subserve such a mechanism. Moreover, cyclothymic women, with their temperamental bcapriciousnessQ, would make them difficult to attain for lovemaking, thereby increasing the likelihood that the most brobustQ male could be found, leading to a better chance for adaptive survival of offspring emerging from such unions on a protected territory with advantages of nourishment and opportunities. Cyclothymic traits appear to lie on a polygenic continuum between excessive temperament and bipolar disorder. Indeed, clinically identified cyclothymes have patterns of familial affective illness, as one would expect for a forme fruste disorder (Akiskal et al., 1977). Cyclothymia has also been observed in the juvenile offspring of bipolar probands (Akiskal et al., 1995). Hypothetically, this temperament might represent one of the inherited trait diatheses for bipolar disorder. For instance,
moody–temperamental individuals are overrepresented in the bdiscordantQ monozygotic co-twins of bipolar patients (Bertelsen et al., 1977). Alternatively, and in a more theoretical vein, bipolar illness might be the genetic reservoir for the desirable cyclothymic traits in the population at large (Akiskal, 2000). These desirable traits, upheld in our TEMPS-A research (Akiskal et al., 2005a,b,c, this issue) and summarized in Table 2, correlated highly with novelty seeking (+0.49) and curiously positively with harm avoidance as well (+0.35). The latter might be hypothesized to represent a bprotectiveQ break against the dangers of the most extremes of risk-taking.
4. Implications for therapy The foregoing data and considerations have important implications for the treatment of mood disorders, particularly for the treatment of bipolar disorders. Because dilute expressions of the illness may persist between major episodes, baggressive treatmentQ with mood stabilizers can comprise adaptive functioning and what is unique to the patient as a person. Except in the acute phases of the illness, the emphasis in treatment should be more on functioning than complete mood stabilization (Akiskal and Akiskal, 2005, in press). There are also psychotherapeutic implications (Akiskal, 1992b). Generalized anxious temperament can benefit from meditation, a phobic temperament from cognitive behavioral approaches, a dysthymic individual from work as therapy, and the cyclothymic would require rhythmotherapy and limit setting. Hyperthymic individuals are action-oriented rather than psychologically oriented, and typically shun psychiatrists and psychotherapists. They are more interested in running the world than bbeing lectured toQ about the desirability of change of behavior at a time of major conflict. The approach to such individuals in psychotherapy is among the most challenging in our field. The inflexibility of their otherwise adaptive traits is at the root of the sexual and financial scandals and tragedies (Akiskal, 2000) that great men bring upon themselves (this temperament is more prevalent in men [Placidi et al., 1998]).
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5. Concluding remarks We have presented a theoretical Darwinian framework for bipolar illness. In an oligogenic model, the constituent traits of this illness may have emerged for survival and adaptive roles in the evolutionary past of our species. These roles include, among others, exploration, territoriality, leadership, social organization, mate selection, and caring for others. The adaptive role of behavioral traits implicated in human evolution may actually transcend the individual and involve the social group at large (Pepper, 2000; Fletcher and Zwick, 2004). Cloninger (1986, 1987) has suggested that harmavoidant and novelty-seeking reaction patterns arise from multifactorial phylogenetic mechanisms, which, in their boptimaQ, are advantageous to the adaptation and survival of the individual. It is also likely that even in their extreme expression, each reaction or temperament type might confer advantages at times of new environmental challenges; thereby conferring survival advantages to the social group at large. In other words, individual temperamental excesses, while not bidealQ or optimal for a given person who expresses them at a time of challenge, may nonetheless in aggregate with other extreme temperaments serve as boptimaQ for a given society—hence to the evolutionary adaptation of our species at large. If nothing else, this should lead to greater tolerance to human diversity: extreme types may hold the genetic keys to our adaptation in the world we inhabit—the planet we share. Indeed, it has been suggested that human evolution has occurred because of a few people with the requisite adaptability in the face of new environments created by ecological disasters (Potts, 1997). From a therapeutic standpoint, understanding the evolutionary context of human behavior should help the transition away from the concept of personality disorder (with its emphasis on what is negative and malfunctioning in one’s personality domain) to that of temperament (which subsumes both assets and liabilities). Such transition, in turn, should help psychiatry and clinical psychology graduate to a new era in which instead of blaming the patients’ character, mental health professionals will endeavor to teach people how to maximize their personal assets to overcome their disordered interpersonal life.
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In a future contribution, we will pursue the hypothesis that curiosity, novelty-seeking and/or creativity associated with bipolar traits may have played a signal role in the rise of the new humans, including the Homo sapiens, and the extinction of the Neanderthal. Such a hypothesis does not rule out the possibility that social interaction and even mating with the Neanderthal—with their love for the familiar terrain, caring and peaceful attributes—may have contributed to the evolutionary success of the new humans. Some support for these views can be found in the anthropological archaeological record (Mellars, 1995; Wong, 2000; Rigaud and Simek, 2004). More speculatively, the anxious-dysthymic and hyperthymic traits underlying bipolarity may have their origin in the respective mix of Neanderthal and early Homo sapiens or their ancestors; the cyclothymic type might actually reflect a me´lange of the attributes of the two.
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