The Psychology of Hunger

Eating and digestion supply the body with the necessary fuel needed for function and survival. Metabolism is the body's rate of energy (or calorie) utilization and several psychological mechanisms that keep our body in energy homeostasis by regulating the food consumption rate. For example, some psychological signals induce hunger and prompt the need to eat, while others stop the intake of food by producing satiety (the state in which we don't feel hunger anymore).

However, this is not the case as many people believe that hunger and eating simply occur when energy levels in our bodies run low and that we feel full when our immediate energy levels are restored. Our body monitors its energy supplies, but this information interacts with other factors; for example, the amount and variety of food to regulate the food intake—making hunger and satiety not necessarily linked to immediate energy requirements. Moreover, homeostatic mechanisms are designed to prevent us from running low on energy in the first place. In evolutionary terms, an organism that did not eat until its energy supply started to become low (in any absolute sense) would be at a serious survival disadvantage.

Finally, many researchers believe that there is a set point; or, as said biologically, a determined standard; around which body weight (or more accurately, fat mass) is regulated. This view holds that if we tend to overeat or undereat, homeostatic mechanisms alter our energy utilization and hunger to make us return to close to our original weight. But some researchers argue that the set point theory has limitations. They propose that as we overeat or undereat, homeostatic mechanisms make it harder to keep gaining or losing weight, but do not return us to our original weight. This makes us possibly settle in a new weight over time. Stated in a different point of view, "Biology does not determine a fixed body weight but rather, a range or zone of body weight."

Genes and Environment

Some individuals gain weight more easily than others even with less consumption of foods as well as  less fatty food consumption, while there are others who eat in excess with more fatty food and still stay slim for example: South Esat Asians who eat an excessive amount of fat still stay slim while others can gain weight with less amount of fat consumption. The reason for this can be in the genes, making some individuals more susceptible to gaining weight due to low metabolism, while others stay slim due to high metabolism. But there can be hormonal factors which contribute to weight gain and loss as well; such as thyroid conditions, thyroid dominance and menopause in some people. Heredity influences one's basal metabolic rate, causing a tendency to store energy as fat or lean tissue. Identical twins that are raised apart are about as similar body mass as identical twins who are raised together. This makes the genetic factors account for about 40% to 70% of the variation in BMI among both genders.

According to studies, over 200 genes have said to be have been identified as possible contributors to human obesity. However, although heredity affects our susceptibility to obesity, the environment does play a part in causing obesity too. There haven't been much changes in genes in recent decades, but the rate of obesity has had a significant increase. Experts believe the reasons to be the abundance of inexpensive foods that taste good but contain a high percentage of fats and carbs; a cultural emphasis on getting the best value, which contributes to the supersizing of menu items; and the advances in technology, which decrease the need for daily physical activity.

The Pima Indians of Arizona have provided a striking example of the way genes and environment interact in producing obesity. The Pimas have a genetic predisposition to obesity and diabetes, but before the 20th century, both these conditions were rare among the members of the tribe. Their native diet and the physically-active lifestyle prevented their genetic predisposition from expressing itself. But Pimas born after World War II, in particular, have had a dramatic increase rate in obesity with the adoption of a westernized diet and sedentary lifestyle. Today, the Pimas living in Arizona have one of the highest rates of obesity and diabetes in the world. In contrast to this, however, the Pimas living in northwest Mexico have a much lower obesity rate than their Arizona counterparts due to their sticking to a more traditional diet with more performance of physical labour.

Dieting and Weight Loss

However, for millions of overweight people, being fat primes them to stay fat, in part by altering their body chemistry and energy expenditure levels. This is an example of why obese people generally have high levels of insulin (a hormone that is secreted by the pancreas helping convert glucose into fat) than people with normal weight do. Substantial weight gain can also make it hard to exercise vigorously, and dieting slows the basal metabolism as the body responds to food deprivation with a decrease in energy expenditure.

Does this mean that diets are doomed to fail? The common adage of "Ninety-five percent of individuals who lose weight, regain the lost weight within a few years" evolved from a single study that was done decades ago. According to Albert Stunkard, one of the researchers, 100 obesity patients were given a diet and sent off, which was 'state-of-the-art' in 1959. There are no good longterm estimates of weight loss success rates in part because we rarely hear from people who succeed (or fail) on their own without the help from clinics or treatment programmes.

There are reports of around one-third of Americans trying to lose weight, although not all of them are the ones who necessarily need to lose weight. There are significant sex and ethnic differences in dieting emerging from adolescence. Some dieters are motivated by health consequences, while the primary motivators to be slim are psychological concerns and social pressures—especially among women. Which may begin as a diet may, unfortunately, evolve into a life-threatening eating disorder.

Eating Disorders: Anorexia and Bulimia

According to researchers, the motivation of abnormal behaviour (like seen in anorexia and bulimia) could be caused by the contribution of psychological, environmental, and biological factors. Researchers are unable to experiment on individuals affected by these disorders in order to manipulate possible causes to check if individuals become anorexic or bulimic, but they are able to examine the factors associated with the disorders, as well as the changes that occur in the individuals when they are treated successfully.

Risk Factors

Two college freshmen named Sara and Lisa suffered from eating disorders. Sara was a victim of anorexia nervosa, which was an intense fear of being fat, causing her to severely restrict her food intake to the point of self-starvation. Despite looking emaciated and weighing 85 percent less than a person would be expected to be according to the said person's age and height, anorexic patients continue to view themselves as being fat. Anorexia causes a cease in menstruation, produces bone loss, stresses the heart, and increases risk of death.

Individuals like Lisa, who suffers from bulimia nervosa, are also in fear of getting fat. They tend to binge-eat, after which they purge the food by inducing vomiting or using laxatives. Often individuals suffering from bulimia consume between 2,000 to 4,000 calories during their binges. In some cases, they tend to consume around 20,000 calories per day. Although most bulimics are of normal body weight, repeated purging can cause severe physical consequences; which include gastric problems and badly-eroded teeth. Whereas most anorexics do not see their food restriction as problematic, bulimics typically do. However, they find it extremely difficult to alter their binge-purge pattern.

According to Becker, in 1999, around 90 percent of anorexic and bulimic individuals were women. According to some surveys, up to 10 percent of college women exhibited symptoms of bulimia although the general prevalence among North American women was 1 to 3 percent compared with 0.5 percent for anorexia. The latest statistics will be higher.

Sociocultural Factors

Anorexia and bulimia are more common in industrialized cultures, where being thin is equated to beauty. However, cultural norms alone cannot be held accountable for eating disorders as only a small percentage of women within a particular culture tend to be anorexic or bulimic; personality factors can be part of the issue. Anorexic individuals are often perfectionists. For example; Sara, who was a high-achiever (a highschool valedictorian), strove to live up to lofty self-standards which included strict ideals of an acceptably thin body. For Sara and Lisa, losing weight became a battle for success and control.

Their upbringing too may have played a role in their need for perfectionism and control. According to their description of their parents; they are disapproving, with expectations of abnormally-high achievement standards. For some anorexic children and teens, food refusal may be reinforced by the distress they cause their parents to feel; making self-starvation a way to punish their parents while gaining some control over their lives. As one anorexic patient said in a therapy session: it was like a power thing; I was showing my mother that  I don't need to eat and I can make her mad. The last thing a  parent wants is for you to die. You can get back at anyone, but if I  need to find a way, I had to forgive her as I am killing myself.

For individuals with bulimia, a different pattern from anorexia emerges; tending to be depressed and anxious, with an exhibition of low-impulse control, as well as lacking a stable sense of personal identity. Their food cravings are often caused by stress and negative mood, causing them to binge-eat to temporarily reduce their negative emotional state; followed by feelings of guilt, self-contempt, and anxiety—which is followed by the purging, maybe as a means of reducing these negative feelings.

Genetic Factors

On the biological side, genetic factors appear to predispose some individuals towards eating disorders. The concordance rate of eating disorders is higher among identical twins than among fraternal twins. The concordance rate between first-degree relatives, such as parents and siblings, are also higher than third and fourth-degree relatives. Researchers are searching for specific genes and combination genes that could be contributors to eating disorders.

Anorexia and bulimia exhibit abnormal activity in serotonin, leptin, and other body chemicals. According to the belief of some researchers, neurotransmitter and hormonal imbalances help in the causing of eating disorders; but others propose that the abnormal eating patterns are the initial cause of the chemical changes as a response that, once started, perpetuate eating and digestive irregularities. Other bodily changes also help in the perpetuating of eating disorders. An example of this is the stomach acid which is expelled into the mouth during vomiting, which causes those suffering from bulimia to lose taste sensitivity and also makes the usually unpleasant taste of vomit more tolerable.

Treating eating disorders can be difficult, taking years; but with professional help, around half of all anorexic and bulimic patients are able to make a full recovery while others are able to eat more normally while still maintaining their preoccupation with food and weight.

Personality Disorders: Causal Factors of ASPD

Biological Factors

Research on the biological factors of Antisocial Personality Disorder (ASPD) has focused on both genetic and psychological factors. The concordance rate of genetic predisposition shows a higher evident rate among identical twins than in fraternal twins for ASPD. Adoption study conclusions are similar, too. When researchers compared criminal records of men who were adopted, the rate of criminality was almost twice as high when the biological father had a criminal record and the adoptive father did not—a clear sign of genetic predisposition.

The clue to genetic predisposition factors of antisocial behaviour in individuals could be the relative absence of anxiety and guilt, which seems to characterize Antisocial Personality Disorder. According to many researchers' beliefs, the psychological basis for the disorder may be a dysfunction in the brain structures governing emotional arousal and behavioral self-control. This can result in impulsive behaviour and a clinically under-aroused state; impairing avoidance learning, causing boredom, and encouraging a search for excitement. According to psychological basis, children and adults alike with antisocial behaviour patterns tend to have lower heart rates, particularly under stress.

MRIs of antisocial individuals have shown subtle neurological deficits in their prefrontal lobes—the seat of executive function; which are planning, reasoning, and behavioral inhibition; such neurological deficits are associated with a reduction of autonomic activity. This supports a long-suspected idea of severely antisocial individuals being wired differently at a neurological level, causing them to respond with less arousal and a greater sense of impulsiveness to pleasurable and unpleasurable stimuli alike.

Psychological & Environmental Factors

According to psychodynamic theorists, antisocial personalities are individuals with no conscience. Psychoanalytic theorists believe that such individuals lack anxiety and guilt because they did not develop an adequate superego. The absence of a well-developed superego causes reduction of the restraints on the identity, resulting in impulsive behaviour. Inadequate identification with appropriate adult figures is thought to cause these individuals' failure to develop a strong superego because these figures weren’t either physically or psychologically available to the child. Supporting this position, the absence of the father from home has a higher related incidence of antisocial symptoms in children, even with socioeconomic status equated.

Cognitive theorists believe that an important feature of antisocial individuals is their consistent failure in thinking about—or to anticipate the long-term negative consequences—of their acts. This results in impulsive behaviour, with thought only of their wants of the moment. From this perspective, the key to preventing these individuals from getting themselves into trouble is to help them develop cognitive control (executive function) necessary to think before acting. Learning through modelling can play an important role too.

Many antisocial personalities come from homes of aggressive and inattentive parents. Such parents become role models for aggressive behaviour and disregard for others' needs. Another important environmental factor is exposure to deviant peers. Antisocial children often learn some of their deviant behaviour from peer groups that help model antisocial behaviour and reinforce it with social approval. When environmental factors are combined with a possible genetic predisposition for antisocial behaviour, it clearly encourages a pattern of deviant behaviour.

According to the learning explanations of some biological theorists, it suggests that individuals with antisocial behaviour lack impulse control. Learning theorists believe that the reason for poor impulse control in these individuals occur due to impaired ability to develop conditioned fear responses when they are punished. This results in a deficit of avoidance learning. Hans Eysenck said a person's ability to develop a conscience depended on that person’s ability to learn fear and inhibitory avoidance responses. Individuals who fail in these aspects will have less ability to inhibit their behaviour.

Clinical studies

In accordance with this hypothesis, Adrian Raine and his co-workers did a 14-year follow-up on males who had been subjected to classical conditioning at the age of 15, in which a soft tone had been used as the conditioned stimulus (CS) and a loud averse tone as the unconditioned stimulus (UCS). Conditioned fear was measured by the participant’s skin conductance response when the CS occurred after a number of pairings with the loud UCS. According to the research findings, the men who accumulated a criminal record by the age of 29 had shown poorer conditioning at the age of 15 than those with no criminal record.

According to further studies, major damage to the grey and white matter in the prefrontal cortex, as well as autonomic deficits, can result in pseudo-psychopathic personality in patients with neurological disorders, but it is not known whether individuals with antisocial personality disorder in the community, with no discernible brain trauma, also have subtle prefrontal deficits.

When prefrontal grey and white matter volumes were assessed using structural magnetic resonance imaging in 21 community volunteers with ASPD; as well as in two control groups which comprised of 34 healthy subjects, 26 subjects with substance dependence, and 21 psychiatric controls. The autonomic activity of (skin conductance and heart rate) was assessed during a social stressor in which the participants gave a videotaped speech of their faults.

The ASPD group showed an 11 percent reduction of prefrontal grey matter volume in the absence of ostensible brain lesions and reduced autonomic activity during the stressor. These deficits were a prediction of group membership independent of psychosocial risk factors. These findings are said to be the first evidence of structural brain deficits in ASPD. This prefrontal structural deficit may underlie the low arousal, poor fear conditioning, lack of conscience, and decision-making deficits known to characterize antisocial behaviour.

Causal Factors of Schizophrenia

Schizophrenia has long been a focus of research due to the seriousness of the disorder as well as the many years of anguish and incapacitation experienced by the patients. Predisposition to schizophrenia is high if an immediate family member has the disorder, but there are chances of developing Schizophrenia even without a family history of the disorder.

Biological factors

Genetic predisposition:

Strong evidence exists of genetic predisposition to schizophrenia, but some develop the disorder without family history. The more closely an individual is related to a person with the disorder, the higher the chances are of him developing it. According to studies, identical twins have a higher rate of developing the disorder than fraternal twins. Adoption studies show a higher concordance with biological parents than with adoptive parents.

But genetics is not the only cause; if it was, the concordance rate of schizophrenia in twins would be at 100 percent. Schizophrenia develops in adulthood. Men develop symptoms of schizophrenia in their late teens or early twenties, while women show symptoms of the disorder in their twenties or thirties. More subtle signs of the disorder maybe present earlier, such as poor performance in school, troubled relationships, and lack of motivation.

Brain abnormalities:

Brain scans of such individuals indicate a number of structural abnormalities. According to the Neurodegenerative Hypothesis, the destruction of neural tissue can cause schizophrenia. MRI studies have shown mild to moderate brain atrophy; a general loss or deterioration of neurons in the cerebral cortex and limbic system, together with enlarged ventricles (cavities containing cerebrospinal fluid).

The atrophy is centered in the brain region influencing cognitive process and emotion. This may explain the thought disorders and inappropriate emotions seen in such patients. Likewise, MRI images of the thalamus, which collects and routes sensory input to various parts of the brain, reveal abnormalities as well. This may help account for the disordered attention and perception reported by the patients whose cerebral cortex may be getting garbled with unfiltered information of the thalamus. These structural differences are more common in patients exhibiting negative symptoms.

Biochemical factors:

Dopamine, a major excitatory neurotransmitter, may play a key role in schizophrenia. According to the Dopamine Hypothesis, the symptoms of schizophrenia, specifically the positive symptoms, are produced by overactivity of the dopamine system in areas of the brain which regulate emotional expression, motivational behaviour, and cognitive function.

Individuals diagnosed with schizophrenia have more dopamine receptors on neuron membranes than non-schizophrenics. These receptors seem to be overactive to dopamine stimulation and additionally, the effectiveness of antipsychotic drugs used to treat this disorder are positively related to their ability to reduce dopamine-produced synaptic activity. Other neurotransmitter systems could be involved in this complex disorder, too. Considering the biochemical and brain findings concerning schizophrenia, it is not clear whether they cause the disorder or vice versa.

Psychological factors

Freud and other psychoanalytic thinkers' view of schizophrenia was that it is a retreat from unbeatable stress and conflict. To Freud, schizophrenia represented an example of an extreme defence mechanism of regression, in which such a person retreats to an earlier and more secure (even infantile stage) of psychological development, when faced with overwhelming anxiety. Other psychodynamic thinkers, focusing on the interpersonal withdrawal, which is an important feature of schizophrenia, tend to view the disorder as a retreat from an interpersonal world that’s too stressful to deal with.

Even though Freud’s explanation on regression hasn’t received much direct research support, the belief of stress as a causal factor is accepted today. Some cognitive theorists believe that people with schizophrenia have a defect in the attention mechanism which filters out irrelevant stimuli, making them feel overwhelmed by both internal and external stimuli and in turn, causing sensory input to become a chaotic flood, resulting in irrelevant thoughts and images flashing into consciousness. The stimulus overload produces distractability, thought disorganisation, and a sense of being overwhelmed by disconnected thoughts and ideas.

As one schizophrenic noted, “Everything seems to come pouring in at once…I can’t seem to keep  anything out” (Carson). The recent MRI findings on thalamic abnormalities described earlier may help explain how the stimuli overload could occur through a malfunction of the brain's switchboard.

Environmental factors

Stressful life events seem to play an important role in the emergence of schizophrenic behaviour. Two to three weeks preceding a 'psychotic break', when acute signs of schizophrenia appear, these events tend to cluster. Stressful life events seem to interact with such a person's personality or biological vulnerability factors. A highly-vulnerable individual may require just a small stressful event to reach the breaking point. In a study, psychotic and non-psychotic individuals rated their emotional responses as they encountered stressful events in their daily lives. The psychotic individuals' reactions to their stresses were more intense with negative emotions, suggestive of emotional overactivity being a vulnerability factor.

Family dynamics have for long been a prime suspect in the origins of this disorder, but the search for characteristics of a parent or family causing the disorder has largely been unsuccessful. Significantly, children with biologically normal parents who are raised by adoptive parents with the schizophrenic disorder do not show an increased risk of developing the disorder. Although schizophrenic individuals often are from families with problems, the nature of the seriousness of such problems is not different from those of which non-schizophrenics are raised.

This does not mean that family dynamics are unimportant; it may just mean that a person must have a biological vulnerability factor in order to be affected by stressful family events to such a degree. There is indeed evidence that this vulnerability factor may appear early in life. In a study conducted by researchers, pre-schizophrenic children and their non-schizophrenic brothers and sisters were analysed using home movies of schizophrenic children. Even at these early ages, sometimes a child as young as two years old seem to show more odd and uncoordinated movements and less emotional expressiveness, especially for positive emotions. These odd behavioural patterns may not just reflect a vulnerability factor, but may also help create environmental stress by evoking negative reactions from others.

Although researchers have had difficulty pinpointing family factors contributing to the initial appearance of this disorder, one finding is consistent of previously-hospitalised schizophrenics being more likely to relapse when returned to a home environment that is high in a factor called 'Expressed Emotion'. Expressed emotion involves high levels of criticism, hostility, and over-involvement. One review of 26 studies showed that within 9-12 months of returning home, an average relapse of 48% in patients with  families who were high in expressed emotion, compared with a relapse rate of 21% with families that were low in this factor.

However, before we conclude on high expressed emotions causing relapses in patients, there is a finding from another study worth noting; which are videotapes of actual interactions between patients and their families. Analysis of the videotapes revealed that families who were high in expressed emotion did indeed make more negative comments to patients when they engaged in strange behaviours, but they also showed these patients behaving around four times as many strange behaviours, clouding the issue of what causes what. Thus, high expressed emotion may be a cause of a response to these patients' disordered behaviours; because people with this disorder can be overly sensitive to stress and even mildly negative family reactions could trigger underlying biological vulnerabilities, resulting in a relapse.

Sociocultural factors 

Sociocultural factors are undoubtedly linked to schizophrenia. According to many studies, the highest prevalence of schizophrenia is found in lower socioeconomic populations.Why is this? Is schizophrenia caused due to poverty, or is it an affect of the disorder? Two views tend to give opposite answers. The Social Causation Hypothesis attributes the higher prevalence of schizophrenia  to the higher levels of stress experienced by low-income people, particularly in urban environments.

In contrast, the Social Drift Hypothesis proposes that with the development of schizophrenic disorder, these individuals' personal and occupational functions tends to deteriorate, causing them to drift down the socioeconomic ladder into poverty and migrate to economically depressed urban environments. Perhaps both social causation and social drift maybe at work, for the factors linking poverty, social and environmental stressors, as well as schizophrenia, are undoubtedly complex.

In contrast to most disorders, schizophrenia may be a culture-free disorder. According to a worldwide epidemiological study sponsored by the World Health Organisation, the prevalence of schizophrenia  is not dramatically different throughout the world. Researchers have, however, found that the likelihood of recovery is greater in developing countries than in the developed nations, such as North America and Western Europe. This may be due to stronger community orientation and greater social support extended to disturbed individuals in developing countries.

Schizophrenia reflects complex interactions among psychological, biological, and environmental factors and presents prominent causal factors identified by analysis. Some patients do well with treatment and live productive lives, while others continue to be symptomatic. As this disorder starts in early adulthood, these individuals can benefit from rehabilitation and help them develop management skills, complete education or vocational training, and hold onto a job. This helps with self-sufficiency in people afflicted with schizophrenia.

There is no cure for schizophrenia, but management of symptoms with medication, cognitive behavioural therapy, and supportive psychotherapy. Substance abuse is high in schizophrenic patients, owing to the misuse of drugs, which can make diagnosis harder.