Neurobiological aspects of feeding disorders

Bloody Women: A Discourse Analysis of Amenorrhea as a Symptom of Anorexia Nervosa

Amenorhea, the absence of menstruation, is now considered to be a major diagnostic symptom of anorexia nervosa and has been interpreted as `psychobiological' retreat from adult womanhood. However, such interpretations may be overly simplistic. This article draws on poststructuralist theory to examine the ways in which menstruation and amenorrhea are discursively constituted in relation to constructions of femininity. It is based on interviews with 23 women (21 who had been diagnosed as anorexic and two who were self-diagnosed). Discourse analysis of the interviews indicated that `menstruation' was negatively construed as a signifier of `femininity'. However, it signified a very specific `femininity' that was alien, out of control, highly emotional, sexual, vulnerable and dangerous. It is argued that amenorrhea in anorexia may signify a rejection of this particular negative construction of femininity' rather than of adulthood or femininity per se.

Verbal hallucinations and language production processes in schizophrenia

How is it that many schizophrenics identify certain instances of verbal imagery as hallucinatory? Most investigators have assumed that alterations in sensory features of imagery explain this. This approach, however, has not yielded a definitive picture of the nature of verbal hallucinations. An alternative perspective suggests itself if one allows the possibility that the nonself quality of hallucinations is inferred on the basis of the experience of unintendedness that accompanies imagery production. Information-processing models of “intentional” cognitive processes call for abstract planning representations that are linked to goals and beliefs. Unintended actions - and imagery - can reflect planning disruptions whereby cognitive products do not cohere with concurrent goals. A model of schizophrenic speech disorganization is presented that postulates a disturbance of discourse planning. Insofar as verbal imagery can be viewed as inwardly directed speech, a consequence of such planning disturbances could be the production of unintended imagery. This link between the outward disorganization of schizophrenic speech and unintended verbal imagery is statistically supported by comparing the speech behavior of hallucinating and nonhallucinating schizophrenics. Studies of “borderline” hallucinations during normal, “goal-less” relaxation and drowsiness suggest that experiential unintendedness leads to a nonpathological variant of hallucinatory otherness that is correctable upon emerging from such passive cognitive states. This contrasts with the schizophrenic case, where nonconcordance with cognitive goals reinforces the unintendedness of verbal images and sustains the conviction of an external source. This model compares favorably with earlier models of verbal hallucinations and provides further evidence for a language production disorder in many schizophrenics.Short Abstract: How is it that many schizophrenics identify certain instances of verbal imagery as hallucinatory? This paper proposes that the critical feature identifying hallucinations is the experience of unintendedness. This experience is nonpathological during passive conscious states but pathological if occurring during goal-directed cognitive processing. A model of schizophrenic speech disorganization is presented that postulates a disturbance of discourse planning that specifies communicative intentions. These alterations could generate unintended verbal imagery as well. Statistical data are offered to support the model, and relevant empirical studies are reviewed.

The role of leptin in anorexia nervosa: clinical implications

Leptin is a hormone with pleiotropic functions affecting several tissues. Because leptin has a crucial role in the adaptation of an organism to semi-starvation, anorexia nervosa (AN) serves as a model disorder to elucidate the functional implications of hypoleptinaemia; vice versa, several symptoms in patients with this eating disorder are related to the low leptin levels, which are characteristic of acute AN. Weight gain in AN patients can induce relative hyperleptinaemia in comparison to controls matched for body mass index; circulating leptin concentrations in AN patients thus transverse from subnormal to supranormal levels within a few weeks. We review findings on leptin secretion in AN and focus on implications, particularly for the hypothalamus-pituitary-gonadal axis, bone mineral density and physical hyperactivity. Undoubtedly, the elucidation of leptin's function as a trigger of diverse neuroendocrine adaptations to a restricted energy intake has substantially advanced our knowledge of the pathogenesis of distinct symptoms of AN, including amenorrhoea that represents one of the four diagnostic criteria. The fact that hypoleptinaemia can induce hyperactivity in a rat model for AN has led to a series of studies in AN patients, which support the notion that application of leptin to severely hyperactive patients might prove beneficial.

Abnormal neuronal network in anorexia nervosa studied with I-123-IMP SPECT

Single photon emission computed tomography was used to study 14 female patients with anorexia nervosa and 8 female normal comparison subjects. Automatic voxel-based analysis of the images was carried out using statistical parametric mapping (SPM) software. Statistics across the entire brain were displayed as Z scores (threshold: P<0.05). Compared with the normal comparison subjects, the anorectic patients were characterized by hypoperfusion in the medial prefrontal cortex and the anterior cingulate gyrus, and hyperperfusion in the thalamus and the amygdala-hippocampus complex. These results suggest that a dysfunction in neuronal circuitry may be related to anorexia nervosa.

Candidate gene polymorphisms in eating disorders

Anorexia nervosa and bulimia nervosa are complex disorders characterized by disordered eating behaviour. Attitudes towards weight and shape as well as the perception of body shape are disturbed. A substantial genetic influence on these disorders has been suggested by formal genetic studies. Obsessive-compulsive behaviour, perfectionism and anxious personality traits seem to occur premorbidly in several patients. Disturbances of neurotransmitter, neuropeptide and neuroendocrine systems have been reported in acutely ill and followed-up patients. Hence, these systems might be involved in the etiology of these eating disorders.Genetic studies on candidate genes have mainly focussed on the serotonergic system and on genes involved in body weight regulation. Up to now, polymorphisms and variations in various genes (e.g. genes for 5-HT receptors, leptin gene, melanocortin MC(4) receptor gene) have been assessed for association and transmission disequilibrium pertaining to anorexia nervosa and/or bulimia nervosa. Most of the studies yielded negative results. Four studies of a polymorphism (-1438 G/A) within the promoter of the 5-HT(2A) gene (5-HT(2A)) revealed an association of the A-allele to anorexia nervosa. However, three studies could not confirm this result. Furthermore, a meta-analysis did not support the positive association. Currently, combined efforts within the European Union will answer the question of whether or not the A-allele is involved in the predisposition to anorexia nervosa. A transmission disequilibrium test is being performed in about 300 trios consisting of a patient with anorexia nervosa and both parents. As candidate gene approaches did not unequivocally identify susceptibility genes (alleles) for anorexia nervosa or bulimia nervosa, systematic model-free genome-wide screenings should also be performed in order to identify currently unknown genes involved in eating disorders. This kind of approach has already been initiated for anorexia nervosa. Genetic research on eating disorders will hopefully lead to new pharmacological treatment strategies.

Neuroanatomy of human appetitive function: A positron emission tomography investigation

OBJECTIVE

The mediating neuroanatomy of human appetitive function is poorly understood. A state induction paradigm was employed, in conjunction with positron emission tomography, to test the hypothesis that limbic/paralimbic regions respond to the desirability of food stimuli.

METHODS

Eight normal subjects were studied during each of three conditions, involving visual exposure to high-caloric food, low-caloric food, and nonfood stimuli. Subjective indices of hunger were measured via analog scales.

RESULTS

Planned contrasts demonstrated significant increases in desire to eat and decreases in left temporoinsular cortical blood flow during the high-caloric versus control conditions.

DISCUSSION

Results implicate the temporo-insular cortex in normal appetitive function, suggesting that activity within this region is associated with the desirability or valence of food stimuli, prior to ingestion. These data will provide a broad foundation for future studies of patients with eating disorders.

Brain hypometabolism of glucose in anorexia nervosa: normalization after weight gain

Using positron emission tomography and (18-F)-fluorodeoxyglucose, we studied cerebral glucose metabolism in 10 anorectic girls within their underweight state and after weight gain. Ten age- and sex-matched healthy volunteers were used as controls. Both groups were scanned during rest, eyes closed and with low ambient noise. In absolute values, the underweight anorectic patients, when compared to control subjects, showed a global (p = 0.002) and regional (p < or = 0.001) hypometabolism of glucose which normalized with weight gain. In relative values, no global difference could be assessed between underweight anorectic patients and controls but a trend can, nevertheless, be observed toward parietal and superior frontal cortex hypometabolism associated with a relative hypermetabolism in the caudate nuclei and in the inferior frontal cortex. After weight gain, all regions normalized for absolute and relative values, although a trend appears toward relative parietal hypometabolism and inferior frontal cortex hypermetabolism in weight gain anorectic patients. Absolute brain glucose hypometabolism might result from neuroendocrinological or morphological aspects of anorexia nervosa or might be the expression of altered neurotransmission following deficient nutritional state. As some differences exists in relative values in underweight patients and tend to persist in weight gain states, this could support a potential abnormal cerebral functioning, a different reaction to starvation within several regions of the brain or different restoration rates according to the region.

Brain hypometabolism of glucose in anorexia nervosa: a PET scan study

Cerebral glucose metabolism was studied in 20 underweight anorectic girls and in 10 age- and sex-matched healthy volunteers using positron emission tomography with (18-F)-fluorodeoxy-glucose. Both groups were scanned during rest, with eye closed and with low ambient noise. Compared to controls, the underweight anorectic group showed a global hypometabolism (p = .002) and an absolute (p < .001) as well as relative (p < .01) hypometabolism of glucose in cortical regions, with the most significant differences found in the frontal and the parietal cortices. Within the underweight anorectic and the control groups, no correlations were found between absolute or relative rCMRGlu and BMI, anxiety scores, or Hamilton scores of depression. Different factors might explain this reduction of glucose metabolism in anorexia nervosa. It might be the consequence of neurophysiological or morphological aspects of anorexia nervosa and/or the result of some associated symptoms such as anxiety or depressed feelings. Supported by cognitive studies, we can also hypothesize a primary corticocerebral dysfunctioning in anorexia nervosa.

Normal gastric antral myoelectrical activity in early onset anorexia nervosa

Anorexia, epigastric discomfort, nausea, and vomiting may result from disordered gastric motility and emptying. These features have been found in many adults with anorexia nervosa, but have never been investigated in early onset anorexia nervosa. In 14 patients with early onset anorexia nervosa (eight of whom had upper gastrointestinal tract symptoms), six children with other eating disorders, four children with non-ulcer dyspepsia, and 10 controls matched for age and sex, the non-invasive technique of surface electrogastrography was used to measure fasting and postprandial gastric antral electrical control activity, which underlies antral motility. The electrical signal was recorded by four bipolar silver/silver chloride electrodes attached to the upper abdomen, amplified and low pass filtered at 0.33 Hz before being displayed on a polygraph, digitised at 1 Hz, and stored on the hard disk of a personal computer for later offline analysis. Patients with non-ulcer dyspepsia had gastric antral dysrhythmias. No significant difference was found in the mean (SD) dominant frequency of the antral electrical control activity between patients with early onset anorexia nervosa (2.86 (0.35) cycles/minute (cpm)), patients with other eating disorders (3.14 (0.65) cpm), and controls (3.00 (0.46) cpm). The amplitude of electrical control activity increased postprandially in all but one subject and the fasting/postprandial amplitude ratio did not significantly differ between patients with early onset anorexia nervosa and controls, though patients with longer established disease had a smaller increase in amplitude. Gastric antral electrical dysrhythmias are not a feature of early onset anorexia nervosa and therefore do not induce or perpetuate food refusal in this disorder.