Personality is a term with many varying connotations, depending on the context of usage. It is a term that may be used to denote a celebrity (a public personality of figure), one’s character and temperament, or the way one comes across to others (he or she has a good personality). In medical and psychological parlance, however, personality is used to denote “those characteristics of a person that account for consistent patterns of feeling, thinking and behaving”; unique and enduring patterns of behavior and emotional response, which make us distinct individuals.
It seems rational to assume that one’s personality is a product of one’s upbringing and experience. We often cluck our tongues disapprovingly and say “Poor boy, with a disturbed background like that, how else would you expect him to behave” or indeed to warmly suggest, “One would expect no less from her; after all she comes from such a good family”. Psychological research seems to support these social assumptions that we regularly make. There is little doubt in the notion that our personalities are in good measure a product of our upbringing, the positive and negative experiences we have in our lives, the human interactions that influence us, and the patterns of emotional response we consequently develop.But is that all? Can every aspect of the human personality be explained on the basis of upbringing and experience? Do disturbed families yield disturbed children who may then grow up into disturbed adults only because of environment? Or are there genetic and other biological factors that influence these developments? Indeed, why do some people from very disturbed backgrounds remain stable and productive, while others from seemingly stable backgrounds display enduring disturbances in their ways of thinking, feeling and behaving? These are questions that continue to befuddle us.
Localising Mind and Brain InteractionsGiven the mind does not exist as a physical entity and is widely regarded as the software (the Brain being the hardware), it seems self evident that disturbances in brain function would have an impact on our mind (and possibly vice-versa). Surely, any affectation of these brain systems is likely to have an influence on our personality? Surely, also, our personalities are likely to result from biological imprints in our brain, imprints that lead to the very consistent patterns of thinking, feeling, and behaving, making us the individuals we are?Perhaps the earliest attempt to link human temperament with the brain was “Phrenology”, the study of the human skull, its characteristics, and the correlation of these with various aspects of behavior, emotion and temperament. From this time emerged also what has become an enduring tradition in clinical neurology practice; repetitive and careful observation and documentation of patients: the symptoms they described, and the signs that were manifest during the clinical examination, an approach that yielded excellent descriptions of emotions, behavior and temperament in brain disorders. Correlating these with studies of brain biology using brain scans, genetic, chemical and hormonal studies etc., and autopsy data, has improved our understanding of mind-brain interactions. The personality in neurological disorders such as epilepsy is now relatively well documented, and we are able to build models linking different brain structures with typical behavioral patterns that are observed in these disorders.
A Tale of Two PersonalitiesWhile there are several striking descriptions in the literature of personality changes associated with brain disease, the illness in which classic personality features are well described is epilepsy, providing a template to understand the neurological contributions to human personality. Epilepsy is a paroxysmal disorder that often begins in childhood or adolescence, and may continue throughout a person’s life. Epilepsy is characterised by recurrent seizures or fits, usually involving loss of consciousness, fall, jerking of the limbs, clenching of the jaws, injury (often tongue bite), and incontinence (involuntarily urination and/or defecation). Epilepsy may, however, also manifest in partial or minor forms as involuntary movements or repetitive behaviors of which the person is unaware or partially aware. The illness which begins as short circuit in normal brain activity is commonly characterised as primary or secondary generalised: primary generalised epilepsy arises from a central pacemaker in the brain and secondary generalised from a distinct part of the brain (usually a lesion or scar) later spreading to involve other parts (generalising). Distinct personality types are described in the two different forms of epilepsy: the obsessive-emotive personality of temporal lobe epilepsy and the labile-disinhibited personality of juvenile myoclonic epilepsy.
The Obsessive NeuroticOne of the most striking descriptions of personality in neurology is in patients with epilepsy that arises from the temporal lobes. The temporal lobes are located on either side of the brain, roughly in the area beneath the ears and are the seat of human memory and emotion. It has been shown in a number of studies that disturbances in this region can result in striking behavioral or cognitive (memory, attention etc.) change.An American neurologist, Normal Geschwind, widely regarded as the father of behavioral neurology, described specific personality features in people with temporal lobe epilepsy. These include:
- A tendency to write copiously (but not necessarily in a creative way) and to keep voluminous diaries (Hypergraphia)
- A tendency to be overly religious, often in a ritualistic manner, out of keeping with the person’s family/ cultural background (Hyper-religiosity)
- A tendency to have a decreased interest in sexual matters (Hypo-sexuality)
- A tendency for anxiety and obsessionality; to dwell on minor matters and to experience difficulty in terminating social intercourse (emotional viscosity or stickiness)
- An increased interest in spiritual or ideational issues in the absence of pragmatic interests
- Turbulent emotions — irritability, agitation, anxiety, restlessness, paranoia etc.
- Mood swings, commonly spells of depression with occasional elation
- Psychotic and quasi-psychotic phenomena; transient hallucinations, delusional thinking etc. occurring on and off
These personality traits have been described mainly in people with chronic temporal lobe epilepsy that failed to respond to anti-epileptic drug therapy. We must remember the vast majority of people with temporal lobe epilepsy are honest, conscientious, sincere and upright members of the community they live in, these positive qualities being aided perhaps by the personality traits described. Only in a small proportion of people, usually those with severe epilepsy, do these traits become severe and/or disabling. In some way therefore, these are probably the behavioral manifestations of the pathology in the brain that most often underlies temporal lobe epilepsy, sclerosis of a part of the temporal lobe called the hippocampus. The hippocampus is a small organ, no larger than a finger joint, which is the storehouse of memory and is located on either side, deep within the brain. Adjacent to it is the amygdala, a multinucleated structure that is believed to play a substantive role in human emotion. There is evolving literature that suggests a role for these structures in various disorders of the mind, schizophrenia and depression for example. One may argue that both behavioural and brain dysfunction are varying manifestations of a common underlying abnormality in brain biology. In disorders like temporal lobe epilepsy the patterns appear to be surfacing early providing the basis for enduring behaviour patterns i.e. the personality.
The Eternal AdolescentIn contrast to the person with Temporal Lobe Epilepsy, the person with Juvenile Myoclonic Epilepsy (JME) has been described as the eternal adolescent by Dieter Janz, the legendary German neurologist who first described the condition in the 1950s. Juvenile Myoclonic Epilepsy is characterised by myoclonic jerks; sudden jerky spasms of the limbs, even the whole body, which might even result in objects flying out of the person’s hand. These myoclonic jerks also have potential to generalise and manifest as a full blown seizure. Further, people with JME also suffer from “absence” periods, when they appear out of touch, albeit briefly, and “photosensitivity”, the sensitivity to flashing lights, these provoking myoclonic jerks or even a seizure episode.Describing the personality of people with JME, Janz and Christian found them to be of average intellectual ability with a tendency to “promise more than they can deliver”. They went on to describe the personality of people with JME as follows. “They often appeared self assured and bragging, the girls and women coquettish, but they only act decidedly mistruthfully and are timid, frightened and inhibited. Their labile feelings of self worth lead them to be both eager to help, to invite, to give, on the one hand and to be able to act in an exaggeratedly sensitive way on the other hand. Their mood changes rapidly and frequently. This makes their contact both charming and difficult. They are easy to encourage and discourage, they are gullible and unreliable. Their suggestibility makes contacts easily but makes trust difficult. This personality profile plays along a scale from likeable nonchalance or timidity, through a psychasthenic syndrome to the extremes represented by sensitive or reckless psychopathy.”In the clinic setting, treating the person with JME can often be an exasperating experience. They seldom follow through on instructions; often break rules willfully; for example, despite knowing that lack of sleep may provoke seizures, they favour late nights. They may be irregular with their epilepsy medication to the point of recklessness. They may show disinhibition in their patterns of interaction, political correctness not being their strength. Indeed, the person with JME demonstrates many features of frontal lobe dysfunction, emphasising the importance of this part of the brain in social behavior.
From Brain Circuits to Personality TraitsThis tale of two personalities in epilepsy indicates clearly the differential role of frontal and temporal brain circuits in human personality development and change. Temporal lobe dysfunction underlies dominant obsessional neurotic personality traits and frontal lobe dysfunction, immature eternal adolescence. To assume, however, a direct impact of these brain circuits on behavioral patterns may be simplistic, as today, the brain is conceived as working in circuits (a sum of parts). However, these observations help establish a general principle that the brain has considerable impact, not only on the behavioral state of a person (current or ongoing dysfunction), but also on behavioral traits (enduring temperamental patterns).What is striking about the personality features in epilepsy is that they become established rather early in the person’s life (much like the illness, which often begins in childhood or in adolescence), and are not only personality changes consequent to progressive brain disease or brain injury as in Stroke, Multiple Sclerosis and Parkinson’s disease. They do therefore reflect to a large extent, the natural history of personality development in the human being, and are probably a product of both brain biology and life experience.
The Inside Man!In highlighting the epilepsy example, it must be borne in mind that the severe personality changes in epilepsy are an exception rather than the norm; and are confined to a small proportion of people with difficult-to-treat epilepsy. Importantly, however, the changes in epilepsy described herein help us understand the biological underpinnings of the human personality, clarifying for us a role for nature, beyond nurture.One wonders if all personality traits have their biological imprints in the brain; that dominant personality trait patterns in each one of us merely reflect the pre-dominance of brain circuits? One may argue that both the behavioral and brain dysfunction in epilepsy are varying manifestations of a common underlying abnormality in brain biology. If that were true, then pray what role doth life experience have in shaping our personalities, you may well ask. Would not a lifetime of coping with the trials and tribulations of illness have an impact on the personality? Would the disability, physical, psychosocial and pragmatic that chronic illness confers on a person, not influence the personality, towards neurotic obsessionality or carefree adolescence? And pray, what lessons do these models have for understanding the personality of people without neurological illness? A plethora of questions assails us and begs for answers; answers that current medical and scientific knowledge do not possess.As medical technology evolves and we begin to visualise brain circuits in action, using techniques like Functional MRI, MRI Tractography and Positron Emission Tomography (PET), we expect to see the links between brain biology and human behavior unravel further. Perhaps, in time, we will all understand this “inside man (or woman)”; the personality that resides in our brains. In the interim, conditions like epilepsy are windows through which we can view the brain and mind. And view the brain and mind we must with compassion and understanding; without stigmatisation; combining science with medicine; cleverness with common sense; knowledge of medicine and the art of clinical practice; all the while thanking people with epilepsy for enhancing our understanding of the brain and mind.