- Email: [email protected]
Associations between psychological profiles and diseases: examining hemispheric dominance and autonomic activation as underlying regulators
Medical Hypotheses (2003) 61(1), 75–79 ª 2003 Elsevier Science Ltd. All rights reserved. doi:10.1016/S0306-9877(03)00111-7
Associations between psychological profiles and diseases: examining hemispheric dominance and autonomic activation as underlying regulators A. Panzer, M. Viljoen Department of Physiology, University of Pretoria, Pretoria, South Africa
Summary Personality profiles are often typical for specific illnesses, e.g., the type A personality and heart disease. We hypothesize that many more such patterns exist, and have developed a scheme in which many diseases can be classified, depending on hemispheric dominance (i.e., integrated, intellectualising or emotional) and type of autonomic control (i.e., dominance of either sympathetic or parasympathetic system, or an increase in both types of autonomic outflow). Our hypothesis is based on recent findings in neurophysiology, involving the early rearing environmental effects on the developing orbitofrontal cortex, and attachment theory. We conclude with implications for therapy, and a discussion of the limitations of our hypothesis. ª 2003 Elsevier Science Ltd. All rights reserved.
INTRODUCTION Many clinicians will agree that patterns exist in human pathology. Some of these have received widespread recognition. The ambitious, hard-driving type A personality is known to be associated with heart disease (1), while the conflict-avoiding, appeasing type C personality is more likely to develop cancer (2). We believe that many more such patterns exist, and have tried to provide an overview (see Table 1). Obviously, any synopsis linking personality patterns with illnesses will inevitably be an oversimplification. We are, however, of the opinion that many of the hypotheses generated here are testable, and may contribute to a more comprehensive and detailed theory of human disease.
In order to explain our hypothesis, we need to first consider the underlying neuroanatomy and neurophysiology, which may have developed differently mainly due to variations in genetic predispositions and infant rearing conditions. We then discuss a scheme into which many personality types can be classified, depending on hemispheric dominance (i.e., integrated, intellectualising or emotional) and type of autonomic control (i.e., dominance of either sympathetic or parasympathetic system, or an increase in both types of autonomic outflow). Then we list examples of diseases, which are associated with our newly defined categories. We conclude with implications for therapy and a discussion of the limitations of our theory.
NEUROANATOMY AND NEUROPHYSIOLOGY Received 23 May 2002 Accepted 11 November 2002
Development
Correspondence to: M. Viljoen PhD, Department of Physiology, University of Pretoria, P.O. Box 2034, Pretoria 0001, South Africa. Phone: +27-12-3192140; Fax: +27-12-321-1679; E-mail: [email protected]
Infants are born with a genetic predisposition (3), which will partly determine the type of pathology they will develop when under severe or continuous stress (4,5). However, apart from the genetic make-up of an
75
76 Panzer and Viljoen
Table 1 A classification of human diseases based on hemispheric dominance and type of autonomic control
Lettering in bold print refers to the psychological state, normal print lists typical diseases, whereas lettering in italics refers to likely early experiences.
individual, early rearing experiences also fundamentally influence outcome. Animal studies have provided conclusive proof that maternal behaviour towards her offspring programs their neuroendocrine responses to stress, and that this strongly influences both their behavioural and immmunological status in adulthood (6). The same holds for human infant development. The primary caregiver is critical in modulating the infant’s physiological arousal. This determines the type and sensitivity of the infant’s developing long-term stress responses, which could range from being protective against or conducive of the development of mental and physical illnesses in adulthood (7). A considerable amount of stimulation is required for normal brain maturation (8). Cortical networks are formed by an initial overabundant production of synapses, which are then sculpted by a process of parcellation, i.e., activity-dependent fine-tuning of connections and loss of surplus circuitry (9). Early experiences are critical in determining the circuit wiring of the orbitofrontal cortex, which largely regulates the responsivity of the stress axes and autonomic nervous system, and monitors and adjusts emotional responses (10). During Medical Hypotheses (2003) 61(1), 75–79
critical periods of maturation, environmental stresses lead to dysregulated levels of stress hormones in the brain, leading to pathomorphogenesis (10). Developing neurons will establish or maintain aberrant connections, or die, if exposed to an adverse rearing environment. This may lead to impaired cortical control over behaviour. Abnormal seizure-like activity (kindling) may occur, which has a hyperactivating influence (9,10). Apart from influences on nerve cells, abnormal rearing conditions also affect neurotransmitters, which are important in the regulation of neural development and plasticity (8). Hemispheric dominance Hemispheric dominance may play a significant role in determining individual disease vulnerability. The left hemisphere is the site of verbal coping, while emotions are felt in the right hemisphere (11,12). For optimal health, integration between the hemispheres has to occur, in which emotions originating from the right hemisphere are recognised and dealt with by the left hemisphere. It seems that people who integrate remain ª 2003 Elsevier Science Ltd. All rights reserved.
Associations between psychological profiles and diseases
healthy, while those who intellectualise while ignoring their emotions (i.e., left dominant) tend to develop physical diseases, and those who feel (i.e., right dominant), but cannot work through their emotions may tend towards psychiatric diseases (9,10,12). If one considers the orbitofrontal, limbic and autonomic systems, the above broad categories may be refined. Autonomic control The orbitofrontal cortex is of major importance, as it is the only brain structure with connections to just about all other regions. It receives input from all sensory associations, has an output to motor areas, and projects extensively to limbic areas (9). Two limbic circuits exist. First, the excitational ventral tegmental limbic system, (encompassing the anterior cingulate, insula, temporal pole, central nucleus of the amygdala, olfactory areas, glutamate responsive NMDA receptors of mesocorticolimbic dopamine neurons in ventral tegmental areas of the anterior reticular formation and centers in the paraventricular nucleus of the hypothalamus), is associated with sympathetic autonomic nervous system activation (9). Second, the inhibitory lateral tegmental limbic circuit (innervating noradrenergic neurons in the medullary solitary nucleus, and the vagal complex in brain stem caudal reticular formation) stimulates the parasympathetic areas of the hypothalamus (9). If the excitational limbic circuit is damaged by extensive parcellation, the inhibitory limbic circuit (and thus the parasympathetic component of the autonomic nervous system) will be dominant (9,10). Parasympathetically mediated passive coping is driven by the inhibitory limbic circuit and leads to withdrawal directed towards the reduction of the emotional impact of stress (9,10). Such individuals will show reduced overt emotionality, but inefficiency under stress in regulating high arousal states. They are vulnerable to overregulation and internalising psychopathologies (9,10). Conversely, damage of the inhibitory circuit will lead to sympathetic dominance, which leads to a susceptibility to underregulation and externalising psychopathologies. Under severe stress, both these circuits may be in a state of activation, leading to increased sympathetic and parasympathetic outflow (9,10). In ideal circumstances, both sympathetic and parasympathetic outflow would be low. DISEASES AND CATEGORIES A summary of the different categories is provided in Table 1. Optimal health ensues when left and right hemispheres are integrated, and all autonomic outflow is ª 2003 Elsevier Science Ltd. All rights reserved.
77
low. This would most likely be the outcome of sensitively responsive mothering. Left hemisphere dominant Intellectualising persons with sympathetic dominance typically suppress their negative emotions like anger and unhappiness. They avoid conflict, try to please, and easily feel responsible for others wrongdoings (13,14). At some stage in their lives such people are bound to feel helpless (12,15). This is a strong trigger for the secretion of cortisol, which is a strong immunosuppressant (12,16,17). Malignant cells and infectious agents are then not kept in check anymore. Cancer or infections (repeated and/or serious) may result (18). The psychological profile would also seem to fit persons with fibromyalgia and chronic pain syndromes (19,20) and ulcerative colitis (18). A possible contributing factor could be a rearing style of conditional love: i.e., affection shown only when the child is ill or ‘good’ (21,22). Intellectualising persons with parasympathetic dominance have usually learnt to suppress all emotions successfully. They are externally driven, with the workaholic as prototype. They often are compulsively selfreliant, accordingly do not feel helpless, and thus do not secrete cortisol (17). However, along with the lack of rise in cortisol, these individuals do not turn to others to help them regulate their over-aroused autonomic nervous system (16). Their autonomic system is thus in a constant state of activation (16), leading to increased levels of noradrenaline, which results in hypertension (7) and later heart disease. Stress-induced noradrenaline activity can cause a suppression of T-helper type 1 responses and cellular immunity, while stimulating Thelper type 2 responses and humeral immunity (23). The immune system of these individuals is usually overactive, and allergies and autoimmune diseases commonly occur in this group (13). Because these persons are usually completely unaware of their emotions, they may interpret their physical manifestations of anxiety on a purely physical basis, e.g., palpitations, light headedness, inability to swallow. They therefore may be diagnosed with somatisation (11,21). Maternal neglect may have played a role in the genesis of the above disorders. If children are exposed to severe physical or sexual abuse in the critical period of brain maturation, the stress overload may lead to limbic kindling, with resultant increased sympathetic and parasympathetic outflow, experienced subjectively as emotional chaos (9,24). One way of coping with these extreme experiences would be to shut off emotions completely, and dissociate. Posttraumatic stress disorder (PTSD) and other dissociative disorders would seem to fit into this category. Dissociation thus has an adaptive function by allowing a person Medical Hypotheses (2003) 61(1), 75–79
78 Panzer and Viljoen
not to become overwhelmed in the face of trauma (25). Imaging studies have shown that combat-related PTSD leads to smaller right hippocampal volumes, and thus presumably dominance of the left hippocampal system (26). Right hemisphere dominant If we now turn towards those individuals who are aware of what they feel, it seems as if this is a protective factor for their immune systems. The emotional individuals are more likely to develop psychiatric than physical disorders. Emotional persons with sympathetic dominance typically feel anxious. Their rearing style was often characterised by unpredictability (22), and early experience with diminished control is a known risk factor for later anxiety (25,27). Anxiety disorders, obsessive-compulsive disorder, panic disorders, and histrionic and schizotypal personality disorders seem to fit into this category. For example, studies have shown that persons with panic disorder had more often experienced early loss of a caregiver or extremely inadequate caregiving, and persons with agoraphobia reported more early separation from their mothers and parental divorce (25). Persons who are aware of their emotions with parasympathetic dominance are characterised by feelings of anger or emptiness. Eating disorders, substance abuse, conduct disorder, depression and narcissistic, borderline and antisocial personality disorders would seem to fit into this category (see below). Maternal rejection may be a common feature of this group. Sexual abuse is extremely common in the histories of patients with borderline personality disorder (25). Imaging studies have shown that severely sexually abused women have smaller left hippocampal volumes, and thus presumably dominance of the right hippocampal system (26). Antisocial personality is associated with harsh discipline, inadequate supervision, prolonged separation from caregivers, unaffectionate mothers and deviant fathers (25). Eating disordered patients have a decreased ability to examine their own psychological states (which is a function of the left hemisphere), and divert distress by focussing on their bodies instead. Their parents typically indicated support, while actually undermining their daughters confidence (25). Anti-serotonin and antidopamine antibodies may play a role in the eating disorders (28). There appears to be a significant genotype-environment interaction in the brain metabolism of serotonin, wherein the ultimate effect of a gene polymorphism is highly dependent on the specific early attachment experience of that individual (29). Children who are exposed to severe emotional abuse (e.g., extreme humiliation) may not be able to cope, and Medical Hypotheses (2003) 61(1), 75–79
simultaneous sympathetic and parasympathetic activation could occur (9). As these children become increasingly shut off from their reasoning capabilities (in the left hemisphere), they may tend towards psychosis (11). Schizophrenia may result. Chronic schizophrenics have significantly reduced gray matter in the left anterior hippocampal amygdalar (12). Furthermore, children at high risk for schizophrenia, show left-sided movement abnormalities when challenged, reflecting overactivity of ascending dopaminergic systems in the right hemisphere (9).
IMPLICATIONS FOR THERAPY Optimal health ensues with integration of reason and emotion. As is well known, those with psychiatric disorders can benefit greatly from therapy designed to strengthen their cognitive and verbal reasoning skills. What is less well recognised, is that those with physical diseases may profit greatly by coming to terms with their suppressed emotions.
LIMITATIONS AND SUGGESTIONS FOR RESEARCH Any theory attempting to explain such a vast and complex subject as the etiology of human disease is bound to be ridden with oversimplifications, omissions and errors. Our theory is no exception. We have not even touched upon important confounding factors such as stress axis over- or underregulation, other important hormones and neurotransmitters, state and/or pulsatility changes, circadian rhythm, type and duration of stress, cytokines, or the influence of behaviour or perception to name just a few (30,31). However, as we are convinced that patterns exist between psychological profiles and disease types, our hypothesis may be a small stepping-stone. Further studies to examine hemispheric dominance and autonomic system activation in typical patient groups may be indicated.
REFERENCES 1. Friedman H. S. Personality and disease: overview, review and preview. In: H. S. Friedman (ed). Personality and Disease. New York: Wiley, 1990: 3–13. 2. Temoshok L. Personality, coping style, emotion and cancer: toward an integrative model. Cancer Surveys 1987; 6: 837–851. 3. Lakatos K., Toth I., Nemoda Z., Ney K., Sasvari-Szekely M., Gervai J. Dopamine D4 receptor (DRD4) gene polymorphism is associated with attachment disorganisation in infants. Mol Psychiatry 2000; 5: 633–637. 4. Collins W. A., Maccoby E. E., Steinberg L., Hetherington E. M., Bornstein M. H. Contemporary research on parenting:
ª 2003 Elsevier Science Ltd. All rights reserved.
Associations between psychological profiles and diseases
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
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16. 17.
the case for nature and nurture. Am Psychol 2000; 55(2): 218–232. Fonagy P. The human genome and the representational world: the role of early mother–infant interaction in creating an interpersonal interpretive mechanism. Bull Menninger Clin 2001; 65(3): 427–448. Worlein J. M., Laudenschlager M. L. Effects of early rearing experiences and social interactions on immune function in nonhuman primates, 3rd Edn R. Ader, D. L. Felton, N. Cohen (eds). Psychoneuroimmunology; vol. 2. San Diego: Academic Press, 2001: 73–86. Luecken L. J. Childhood attachment and loss experiences affect adult cardiovascular and cortisol function. Psychosom Med 1998; 60: 765–772. Joseph R. Environmental influences on neural plasticity, the limbic system, emotional development and attachment: a review. Child Psychiatry Hum Dev 1999; 29(3): 189–208. Schore A. N. Early organization of the nonlinear right brain and development of a predisposition to psychiatric disorders. Dev Psychopathol 1997; 9: 595–631. Schore A. N. The experience-dependent maturation of a regulatory system in the orbital prefrontal cortex and the origin of developmental psychopathology. Dev Psychopathol 1996; 8(1): 59–87. Taylor G. J., Parker J. D. A., Bagby R. M. Emotional intelligence and the emotional brain: points of convergence and implications for psychoanalysis. J Am Acad Psychoanal 1999; 27(3): 339–354. Henry J. P. Psychological and physiological responses to stress: the right hemisphere and the hypothalamo-pituitaryadrenal axis, an inquiry into problems of human bonding. Acta Physiol Scand Suppl 1997; 640: 10–25. Kotler T., Buzwell S., Romeo Y., Bowland J. Avoidant attachment as a risk factor for health. Br J Med Psychol 1994; 67(3): 237–245. Joubert D., Reza Sadeghi M., Elliott M., Devins G. M., Laperriere N., Rodin G. Physical sequelae and self-perceived attachment in adult survivors of childhood cancer. Psycho-Oncology 2001; 10: 284–292. Gunnar M. R. Quality of early care and buffering of neuroendocrine stress reactions: potential effects on the developing brain. Prev Med 1998; 27: 208–211. Pally R. Emotional processing: the mind-body connection. J Psycho-Anal 1998; 79: 349–362. Spangler G., Grossmann K. E. Biobehavioral organization in securely and insecurely attached infants. Child Dev 1993; 64(5): 1439–1450.
ª 2003 Elsevier Science Ltd. All rights reserved.
79
18. Maunder R. G., Hunter J. J. Attachment and psychosomatic medicine: developmental contributions to stress and disease. Psychosom Med 2001; 63: 556–567. 19. McWilliams L. A., Cox B. J., Enns M. W. Impact of adult attachment styles on pain and disability associated with arthritis in a nationally representative sample. Clin J Pain 2000; 16(4): 360–364. 20. Hallberg L. R. M., Carlsson S. G. Psychosocial vulnerability and maintaining forces related to fibromyalgia. Scand J Caring Sci 1998; 12: 95–103. 21. Stuart S., Noyes R. Attachment and interpersonal communication in somatisation. Psychosomatics 1999; 40: 34–43. 22. Watson J. S. Contingency perception and misperception in infancy: some potential implications for attachment. Bull Menninger Clin 2001; 65(3): 296–320. 23. Elenkov I. J., Wilder R. L., Chrousos G. P., Vizi E. S. The sympathetic nerve- an integrative interface between two supersystems: the brain and immune system. Pharmacol Rev 2000; 52: 595–638. 24. Bremner J. D., Southwick S. M., Johnson D. R., Yehuda R., Charney D. S. Childhood physical abuse in combat-related posttraumatic stress disorder. Am J Psychiatry 1993; 150: 235–239. 25. Dozier M., Chase Stovall K. C., Albus K. E. Attachment and psychopathology in adulthood. In: J. Cassidy, P. R. Shaver (eds). Handbook of Attachment: Theory, Research and Clinical Applications. New York: The Guilford Press, 1999: 497–519. 26. Lynch M., Cichetti D. Trauma, mental representation, and the organization of memory for mother-referent material. Dev Psychopathol 1998; 10: 739–759. 27. Chorpita B. F., Barlow D. H. The development of anxiety: the role of control in the early environment. Psychol Bull 1998; 124(1): 3–21. 28. Corcos M., Atger F., Levy-Soussan P. et al. Bulimia nervosa and autoimmunity. Psychiatry Res 1999; 87(1): 77–82. 29. Suomi S. J. Attachment in Rhesus monkeys. In: J. Cassidy, P. R. Shaver (eds). Handbook of Attachment: Theory, Research and Clinical Applications. New York: The Guilford Press, 1999: 181–197. 30. Carter C. S. Neuroendocrine perspectives on social attachment and love. Psychoneuroendocrinology 1998; 23(8): 779–818. 31. Kraemer G. W. Psychobiology of early social attachment in Rhesus monkeys. Ann N Y Acad Sci 1997; 807: 401–418.
Medical Hypotheses (2003) 61(1), 75–79
Associations between psychological profiles and diseases: examining hemispheric dominance and autonomic activation as underlying regulators A. Panzer, M. Viljoen Department of Physiology, University of Pretoria, Pretoria, South Africa
Summary Personality profiles are often typical for specific illnesses, e.g., the type A personality and heart disease. We hypothesize that many more such patterns exist, and have developed a scheme in which many diseases can be classified, depending on hemispheric dominance (i.e., integrated, intellectualising or emotional) and type of autonomic control (i.e., dominance of either sympathetic or parasympathetic system, or an increase in both types of autonomic outflow). Our hypothesis is based on recent findings in neurophysiology, involving the early rearing environmental effects on the developing orbitofrontal cortex, and attachment theory. We conclude with implications for therapy, and a discussion of the limitations of our hypothesis. ª 2003 Elsevier Science Ltd. All rights reserved.
INTRODUCTION Many clinicians will agree that patterns exist in human pathology. Some of these have received widespread recognition. The ambitious, hard-driving type A personality is known to be associated with heart disease (1), while the conflict-avoiding, appeasing type C personality is more likely to develop cancer (2). We believe that many more such patterns exist, and have tried to provide an overview (see Table 1). Obviously, any synopsis linking personality patterns with illnesses will inevitably be an oversimplification. We are, however, of the opinion that many of the hypotheses generated here are testable, and may contribute to a more comprehensive and detailed theory of human disease.
In order to explain our hypothesis, we need to first consider the underlying neuroanatomy and neurophysiology, which may have developed differently mainly due to variations in genetic predispositions and infant rearing conditions. We then discuss a scheme into which many personality types can be classified, depending on hemispheric dominance (i.e., integrated, intellectualising or emotional) and type of autonomic control (i.e., dominance of either sympathetic or parasympathetic system, or an increase in both types of autonomic outflow). Then we list examples of diseases, which are associated with our newly defined categories. We conclude with implications for therapy and a discussion of the limitations of our theory.
NEUROANATOMY AND NEUROPHYSIOLOGY Received 23 May 2002 Accepted 11 November 2002
Development
Correspondence to: M. Viljoen PhD, Department of Physiology, University of Pretoria, P.O. Box 2034, Pretoria 0001, South Africa. Phone: +27-12-3192140; Fax: +27-12-321-1679; E-mail: [email protected]
Infants are born with a genetic predisposition (3), which will partly determine the type of pathology they will develop when under severe or continuous stress (4,5). However, apart from the genetic make-up of an
75
76 Panzer and Viljoen
Table 1 A classification of human diseases based on hemispheric dominance and type of autonomic control
Lettering in bold print refers to the psychological state, normal print lists typical diseases, whereas lettering in italics refers to likely early experiences.
individual, early rearing experiences also fundamentally influence outcome. Animal studies have provided conclusive proof that maternal behaviour towards her offspring programs their neuroendocrine responses to stress, and that this strongly influences both their behavioural and immmunological status in adulthood (6). The same holds for human infant development. The primary caregiver is critical in modulating the infant’s physiological arousal. This determines the type and sensitivity of the infant’s developing long-term stress responses, which could range from being protective against or conducive of the development of mental and physical illnesses in adulthood (7). A considerable amount of stimulation is required for normal brain maturation (8). Cortical networks are formed by an initial overabundant production of synapses, which are then sculpted by a process of parcellation, i.e., activity-dependent fine-tuning of connections and loss of surplus circuitry (9). Early experiences are critical in determining the circuit wiring of the orbitofrontal cortex, which largely regulates the responsivity of the stress axes and autonomic nervous system, and monitors and adjusts emotional responses (10). During Medical Hypotheses (2003) 61(1), 75–79
critical periods of maturation, environmental stresses lead to dysregulated levels of stress hormones in the brain, leading to pathomorphogenesis (10). Developing neurons will establish or maintain aberrant connections, or die, if exposed to an adverse rearing environment. This may lead to impaired cortical control over behaviour. Abnormal seizure-like activity (kindling) may occur, which has a hyperactivating influence (9,10). Apart from influences on nerve cells, abnormal rearing conditions also affect neurotransmitters, which are important in the regulation of neural development and plasticity (8). Hemispheric dominance Hemispheric dominance may play a significant role in determining individual disease vulnerability. The left hemisphere is the site of verbal coping, while emotions are felt in the right hemisphere (11,12). For optimal health, integration between the hemispheres has to occur, in which emotions originating from the right hemisphere are recognised and dealt with by the left hemisphere. It seems that people who integrate remain ª 2003 Elsevier Science Ltd. All rights reserved.
Associations between psychological profiles and diseases
healthy, while those who intellectualise while ignoring their emotions (i.e., left dominant) tend to develop physical diseases, and those who feel (i.e., right dominant), but cannot work through their emotions may tend towards psychiatric diseases (9,10,12). If one considers the orbitofrontal, limbic and autonomic systems, the above broad categories may be refined. Autonomic control The orbitofrontal cortex is of major importance, as it is the only brain structure with connections to just about all other regions. It receives input from all sensory associations, has an output to motor areas, and projects extensively to limbic areas (9). Two limbic circuits exist. First, the excitational ventral tegmental limbic system, (encompassing the anterior cingulate, insula, temporal pole, central nucleus of the amygdala, olfactory areas, glutamate responsive NMDA receptors of mesocorticolimbic dopamine neurons in ventral tegmental areas of the anterior reticular formation and centers in the paraventricular nucleus of the hypothalamus), is associated with sympathetic autonomic nervous system activation (9). Second, the inhibitory lateral tegmental limbic circuit (innervating noradrenergic neurons in the medullary solitary nucleus, and the vagal complex in brain stem caudal reticular formation) stimulates the parasympathetic areas of the hypothalamus (9). If the excitational limbic circuit is damaged by extensive parcellation, the inhibitory limbic circuit (and thus the parasympathetic component of the autonomic nervous system) will be dominant (9,10). Parasympathetically mediated passive coping is driven by the inhibitory limbic circuit and leads to withdrawal directed towards the reduction of the emotional impact of stress (9,10). Such individuals will show reduced overt emotionality, but inefficiency under stress in regulating high arousal states. They are vulnerable to overregulation and internalising psychopathologies (9,10). Conversely, damage of the inhibitory circuit will lead to sympathetic dominance, which leads to a susceptibility to underregulation and externalising psychopathologies. Under severe stress, both these circuits may be in a state of activation, leading to increased sympathetic and parasympathetic outflow (9,10). In ideal circumstances, both sympathetic and parasympathetic outflow would be low. DISEASES AND CATEGORIES A summary of the different categories is provided in Table 1. Optimal health ensues when left and right hemispheres are integrated, and all autonomic outflow is ª 2003 Elsevier Science Ltd. All rights reserved.
77
low. This would most likely be the outcome of sensitively responsive mothering. Left hemisphere dominant Intellectualising persons with sympathetic dominance typically suppress their negative emotions like anger and unhappiness. They avoid conflict, try to please, and easily feel responsible for others wrongdoings (13,14). At some stage in their lives such people are bound to feel helpless (12,15). This is a strong trigger for the secretion of cortisol, which is a strong immunosuppressant (12,16,17). Malignant cells and infectious agents are then not kept in check anymore. Cancer or infections (repeated and/or serious) may result (18). The psychological profile would also seem to fit persons with fibromyalgia and chronic pain syndromes (19,20) and ulcerative colitis (18). A possible contributing factor could be a rearing style of conditional love: i.e., affection shown only when the child is ill or ‘good’ (21,22). Intellectualising persons with parasympathetic dominance have usually learnt to suppress all emotions successfully. They are externally driven, with the workaholic as prototype. They often are compulsively selfreliant, accordingly do not feel helpless, and thus do not secrete cortisol (17). However, along with the lack of rise in cortisol, these individuals do not turn to others to help them regulate their over-aroused autonomic nervous system (16). Their autonomic system is thus in a constant state of activation (16), leading to increased levels of noradrenaline, which results in hypertension (7) and later heart disease. Stress-induced noradrenaline activity can cause a suppression of T-helper type 1 responses and cellular immunity, while stimulating Thelper type 2 responses and humeral immunity (23). The immune system of these individuals is usually overactive, and allergies and autoimmune diseases commonly occur in this group (13). Because these persons are usually completely unaware of their emotions, they may interpret their physical manifestations of anxiety on a purely physical basis, e.g., palpitations, light headedness, inability to swallow. They therefore may be diagnosed with somatisation (11,21). Maternal neglect may have played a role in the genesis of the above disorders. If children are exposed to severe physical or sexual abuse in the critical period of brain maturation, the stress overload may lead to limbic kindling, with resultant increased sympathetic and parasympathetic outflow, experienced subjectively as emotional chaos (9,24). One way of coping with these extreme experiences would be to shut off emotions completely, and dissociate. Posttraumatic stress disorder (PTSD) and other dissociative disorders would seem to fit into this category. Dissociation thus has an adaptive function by allowing a person Medical Hypotheses (2003) 61(1), 75–79
78 Panzer and Viljoen
not to become overwhelmed in the face of trauma (25). Imaging studies have shown that combat-related PTSD leads to smaller right hippocampal volumes, and thus presumably dominance of the left hippocampal system (26). Right hemisphere dominant If we now turn towards those individuals who are aware of what they feel, it seems as if this is a protective factor for their immune systems. The emotional individuals are more likely to develop psychiatric than physical disorders. Emotional persons with sympathetic dominance typically feel anxious. Their rearing style was often characterised by unpredictability (22), and early experience with diminished control is a known risk factor for later anxiety (25,27). Anxiety disorders, obsessive-compulsive disorder, panic disorders, and histrionic and schizotypal personality disorders seem to fit into this category. For example, studies have shown that persons with panic disorder had more often experienced early loss of a caregiver or extremely inadequate caregiving, and persons with agoraphobia reported more early separation from their mothers and parental divorce (25). Persons who are aware of their emotions with parasympathetic dominance are characterised by feelings of anger or emptiness. Eating disorders, substance abuse, conduct disorder, depression and narcissistic, borderline and antisocial personality disorders would seem to fit into this category (see below). Maternal rejection may be a common feature of this group. Sexual abuse is extremely common in the histories of patients with borderline personality disorder (25). Imaging studies have shown that severely sexually abused women have smaller left hippocampal volumes, and thus presumably dominance of the right hippocampal system (26). Antisocial personality is associated with harsh discipline, inadequate supervision, prolonged separation from caregivers, unaffectionate mothers and deviant fathers (25). Eating disordered patients have a decreased ability to examine their own psychological states (which is a function of the left hemisphere), and divert distress by focussing on their bodies instead. Their parents typically indicated support, while actually undermining their daughters confidence (25). Anti-serotonin and antidopamine antibodies may play a role in the eating disorders (28). There appears to be a significant genotype-environment interaction in the brain metabolism of serotonin, wherein the ultimate effect of a gene polymorphism is highly dependent on the specific early attachment experience of that individual (29). Children who are exposed to severe emotional abuse (e.g., extreme humiliation) may not be able to cope, and Medical Hypotheses (2003) 61(1), 75–79
simultaneous sympathetic and parasympathetic activation could occur (9). As these children become increasingly shut off from their reasoning capabilities (in the left hemisphere), they may tend towards psychosis (11). Schizophrenia may result. Chronic schizophrenics have significantly reduced gray matter in the left anterior hippocampal amygdalar (12). Furthermore, children at high risk for schizophrenia, show left-sided movement abnormalities when challenged, reflecting overactivity of ascending dopaminergic systems in the right hemisphere (9).
IMPLICATIONS FOR THERAPY Optimal health ensues with integration of reason and emotion. As is well known, those with psychiatric disorders can benefit greatly from therapy designed to strengthen their cognitive and verbal reasoning skills. What is less well recognised, is that those with physical diseases may profit greatly by coming to terms with their suppressed emotions.
LIMITATIONS AND SUGGESTIONS FOR RESEARCH Any theory attempting to explain such a vast and complex subject as the etiology of human disease is bound to be ridden with oversimplifications, omissions and errors. Our theory is no exception. We have not even touched upon important confounding factors such as stress axis over- or underregulation, other important hormones and neurotransmitters, state and/or pulsatility changes, circadian rhythm, type and duration of stress, cytokines, or the influence of behaviour or perception to name just a few (30,31). However, as we are convinced that patterns exist between psychological profiles and disease types, our hypothesis may be a small stepping-stone. Further studies to examine hemispheric dominance and autonomic system activation in typical patient groups may be indicated.
REFERENCES 1. Friedman H. S. Personality and disease: overview, review and preview. In: H. S. Friedman (ed). Personality and Disease. New York: Wiley, 1990: 3–13. 2. Temoshok L. Personality, coping style, emotion and cancer: toward an integrative model. Cancer Surveys 1987; 6: 837–851. 3. Lakatos K., Toth I., Nemoda Z., Ney K., Sasvari-Szekely M., Gervai J. Dopamine D4 receptor (DRD4) gene polymorphism is associated with attachment disorganisation in infants. Mol Psychiatry 2000; 5: 633–637. 4. Collins W. A., Maccoby E. E., Steinberg L., Hetherington E. M., Bornstein M. H. Contemporary research on parenting:
ª 2003 Elsevier Science Ltd. All rights reserved.
Associations between psychological profiles and diseases
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
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