Eating Disorders in Schizophrenia

Daily struggles with management strategies may lead physicians to raise certain questions about the prediction of illness courses. Among these questions are "Which symptoms are transient?" "Which are lasting?" and "Which should be prioritized in patient care?" There are tacit operational rules within medical practice that dictate which symptoms to focus on from a hierarchic list.

In this context, eating disorders in patients with schizophrenia have been underappreciated and poorly studied within the traditional diagnostic systems in mental illness. Even when they are recognized, there is often unsubstantiated optimism that eating-related symptoms will disappear as psychosis abates. On the other hand, the psychiatrist may have a speculative skepticism, regarding schizophrenia as encompassing an inability to comply with prescribed ways of living. This may reflect emphasis on overt behaviors in the clinical management of schizophrenia, with less concern about the cognitive drives behind them.

We have observed that patients with schizophrenia have disturbances in eating behaviors that make up an entire spectrum of eating disorders, including disinhibited as well as restrictive eating associated with underlying preoccupation with body image.¹ Eating-related cognitive dimensions did not correlate with objective measures of severity of overt psychotic symptoms measured by the Positive and Negative Symptom Scale (PANSS),² but instead, correlated strongly with patients' subjective perception of distress associated with psychiatric symptoms reported on the McLean Hospital 32-item Behavior and Symptom Identification Scale (BASIS-32).³

Determining whether eating disturbance is a comorbid condition in a subgroup of patients with schizophrenia or part of the broader schizophrenic spectrum disorder has important therapeutic implications for long-term outcome. Through functional profiling of phenotypic manifestations, we may be able to identify subgroups of schizophrenia with potential biologic overlap with eating disorders. This should be followed by a search for genetic correlates of variability.

The coexistence of eating disturbance and schizophrenia is not a new phenomenon; in fact, it has been observed by many clinicians over the years. Kraepelin⁴ and Bleuler⁵ described disorganized and uncontrolled food intake as being characteristic of schizophrenia. Bruch,⁶ on the other hand, suggested that overeating in schizophrenia is an adaptive defense against stress, used for the maintenance of self-control; she referred to a monozygotic twin study in which Kallman observed greater weight as a favorable prognostic sign, since the heavier twin did not become psychotic. However, these early descriptions do not suggest cognitive awareness or deliberateness of behaviors.

Recent molecular examinations have assumed biologic differences in hunger, satiation, and satiety mechanisms in schizophrenia and have focused on metabolic signals. The assumption in most is that the homeostatic signals are offset by schizophrenia or by psychotropic medications. But this assumption is challenged by the heterogeneous patterns of weight and energy consumption changes observed in patients with identical diagnoses and medications.

The hypothalamic sum of physiologic feeding signals can easily be overridden by cortical signals related to emotions and environments. The salience of the motivation to eat; whether this actually results in enough drive to lead to active seeking of food; factors involved in eating termination; the actual hedonic value of the food; and how that changes future expectations of food reward and determines future feeding behaviors are all big chunks of the missing picture. Such cognitive processes may account in part for the individual variability in changes of food intake and body weight associated with the illness and its medications.

What kind of cognitive schemas drive eating and related behaviors in schizophrenia? Do patients have purposeful behaviors or is a compelling impulsivity accompanied by the presence of acknowledgment?

Distortions of body image and a deficient sense of self-effectiveness have been recognized as fundamental underlying features of schizophrenia.⁷ Such cognitive processes may predispose patients with schizophrenia to eating disorders. Many patients with schizophrenia will acknowledge body dissatisfaction and attempts at weight reduction, characterized by periods of restrictive eating, long-term unsuccessful diets that result in demoralization and cycles of binges and fasts. Some patients will deny body image preoccupations and concede the presence of less significant reasons for incessant calisthenics and rigid dietary restrictions, such as the need to fit into old clothes because there is no money for new ones.

Regarding uncontrolled intake, which has received more attention than food restriction in schizophrenia, some patients acknowledge eating large quantities of food after attempted periods of purposeful dieting, but without a subjective sense of loss of control over food intake. This is not a binge in its strict sense under DSM operational terms. Lack of insight is often regarded as a sign of psychosis. However, awareness or insight is not consistently present (nor are they all—or—nothing concepts) in other psychiatric illnesses, including eating disorders. In fact, one of the most distinctive characteristics of anorexia nervosa is a lack of appropriate concern about or denial of the seriousness of low body weight.⁸

Although it is a key drive for anorexic behaviors, the body conceptualization disturbance in anorexia nervosa is not well defined. There is considerable variation in the presence and severity of various observed behaviors and psychological states, such as denial of illness, motivation to change behavior, fear of changing behavior, and sense of adequacy and self-competence.⁹ Similarly, in bulimia nervosa, the International Classification of Diseases-¹⁰ criterion of "intrusive dread of fatness" and the DSM-IV criterion of "self-evaluation unduly influenced by body shape and weight" are not reflective of good insight. Eating disorders resemble schizophrenia in the fixation on thinness, perceptual distortions of somatic stimuli, perseveration over hips and thighs, and the bizarreness of beliefs and rituals related to eating.

To add further to the complexity, psychiatric symptoms fluctuate in qualitative as well as quantitative terms. When, during fluctuations in insight, a certain threshold of awareness is absent, accompanied by ego-syntonicity of excessive ideations and stereotypic behaviors, eating disorders have reached psychotic proportions. Indeed, for years, anorexia nervosa was considered a forme fruste of schizophrenia. Even now, in settings in which physicians are less familiar with eating disorders, such a complex of symptoms is much more likely to be diagnosed as schizophrenia.