Intellect, perceptual characteristics, and weight gain in anorexia nervosa

Neuropsychology of eating disorders: 1995-2012

Eating disorders are considered psychiatric pathologies that are characterized by pathological worry related to body shape and weight. The lack of progress in treatment development, at least in part, reflects the fact that little is known about the pathophysiologic mechanisms that account for the development and persistence of eating disorders. The possibility that patients with eating disorders have a dysfunction of the central nervous system has been previously explored; several studies assessing the relationship between cognitive processing and certain eating behaviors have been conducted. These studies aim to achieve a better understanding of the pathophysiology of such diseases. The aim of this study was to review the current state of neuropsychological studies focused on eating disorders. This was done by means of a search process covering three relevant electronic databases, as well as an additional search on references included in the analyzed papers; we also mention other published reviews obtained by handsearching.

Predictors of neuropsychological recovery in treatment for anorexia nervosa

Previous research indicates that individuals with Anorexia Nervosa (AN) often experience some degree of neuropsychological dysfunction. Although most aspects of cognition improve with treatment, factors that predict neuropsychological improvement remain elusive. The present study investigated whether cognitive reserve, the estimated level of premorbid cognitive functioning, and AN subtype predicted neuropsychological improvement during inpatient treatment for AN. Neuropsychological functioning was assessed pre- and post-hospitalization in 28 women with AN (18 with restricting type and 10 with binge-eating/purging type), and cognitive reserve was estimated at admission using a word reading test. Level of cognitive reserve and AN subtype were both significant predictors of neuropsychological improvement in this sample. Cognitive reserve was significantly associated with improvements in verbal memory, semantic fluency, basic auditory attention and visuospatial construction. Participants with AN binge-eating/purging type demonstrated significantly greater neuropsychological improvement during treatment than did participants with AN restricting type. Information about cognitive reserve and AN subtype may provide clinicians with valuable prognostic information and help guide treatment.

In first presentation adolescent anorexia nervosa, do cognitive markers of underweight status change with weight gain following a refeeding intervention?

OBJECTIVE

To determine the nature and severity of cognitive functioning impairment in adolescent anorexia nervosa (AN) when underweight and following weight gain.

METHOD

In 37 first admission adolescent (12-18 years) AN patients and 45 matched controls, general cognitive functions were assessed at baseline and follow-up using the IntegNeuro-computerized battery. AN participants were tested between days 3 and 10 of their admission when underweight, with retesting conducted after weight restoration.

RESULTS

When underweight, AN participants performed more poorly than controls on sensori-motor speed tasks and exhibited a susceptibility to interference, but had superior working memory. Once the weight is restored, individuals significantly improved relative to their own performance. Relative to controls, they were significantly faster on attention and executive function tasks, exhibited superior verbal fluency, working memory, and a significantly superior ability to inhibit well-learnt responses.

DISCUSSION

Cognitive impairments in adolescent AN appear to normalize with refeeding and weight gain.

Central coherence in eating disorders: a systematic review

BACKGROUND

This review systematically appraised the research evidence for local versus global information processing to test the hypothesis that people with eating disorders (ED) had weak central coherence.

METHOD

Searches on Medline, EMBASE, PsycINFO and ISI Web of Science databases were conducted in November 2006 and subsequently updated in September 2007. Each search was conducted in two steps: (1) neuropsychological tasks measuring central coherence and (2) words related to cognitive functioning in eating disorders. Data were summarized in a meta-analysis if the number of studies for a given test was >5.

RESULTS

Data were extracted from 16 studies. Meta-analyses were conducted for four tasks obtaining moderate effect sizes. The majority of studies found global processing difficulties across the ED spectrum. The results are less clear regarding local processing.

CONCLUSIONS

People with ED have difficulties in global processing. It is less certain as to whether they have superior local processing. Currently, there is insufficient evidence to refute the weak central coherence hypothesis.

Neuropsychological studies in anorexia nervosa

Neuropsychological findings in eating disorders are somewhat inconsistent. This may be because individual studies have used a broad range of tests on relatively small, heterogeneous clinical groups, thus limiting the detection of subtle neuropsychological differences in these patients. Therefore, rather than using broad assessments of a variety of neuropsychological functions, adoption of a more focused, hypothesis-driven approach based on clinical practice is proposed. This will allow more in-depth investigations of targeted functions and will improve the chances of detecting a problem, of exploring its ecologic validity, and of tailoring a treatment. We have demonstrated this approach using our neuropsychological studies of cognitive flexibility in anorexia nervosa (AN).

Neuropsicologia dos transtornos alimentares: revisão sistemática da literatura

ANTECEDENTES: A etiologia dos transtornos alimentares (TA) ainda não se encontra estabelecida. Dentre os diversos fatores envolvidos, a hipótese de uma disfunção do sistema nervoso central tem sido explorada de diversas maneiras. Assim, a avaliação neuropsicológica de pacientes com TA tem por finalidade investigar a ocorrência de déficits cognitivos associados a estas patologias. OBJETIVOS: O objetivo deste artigo é avaliar o estado atual das investigações sobre a avaliação neuropsicológica em pacientes com TA. MÉTODOS: Foi realizada uma pesquisa bibliográfica - utilizando as seguintes bases de dados como estratégias de procura: MedLINE, PsychoINFO, LILACS e Cochrane Data Bank -, procurando artigos relacionados ao tema e publicados até o ano de 2004. RESULTADOS: A anorexia nervosa é o transtorno alimentar que conta com mais estudos neuropsicológicos e, de uma forma geral, os resultados apontam para déficits de atenção, déficits viso-espaciais e de viso-construção. Na bulimia nervosa, as alterações mais encontradas são déficits de atenção seletiva e das funções executivas. O transtorno da compulsão alimentar periódica ainda não conta com estudos neuropsicológicos até o momento. Após um tratamento bem-sucedido do transtorno alimentar, embora haja uma diminuição dos déficits cognitivos, algumas alterações cognitivas parecem persistir. CONCLUSÕES: Os transtornos alimentares parecem estar associados a algum grau de disfunção neuropsicológica, muito embora as funções específicas que se apresentam deficitárias variem entre os estudos encontrados, talvez em decorrência de variações metodológicas. O fato de que, após o tratamento, alguns pacientes apresentem uma melhora no funcionamento cognitivo poderia indicar que, em alguns casos, os déficits seriam funcionais. A ausência de melhora no funcionamento cognitivo de alguns pacientes, após diversas formas de intervenção, pode sugerir que estes déficits antecederiam o desenvolvimento dos transtornos alimentares, podendo, assim, contribuir para seu desenvolvimento ou para um pior prognóstico. O melhor delineamento do perfil cognitivo dos pacientes com transtorno alimentar torna-se importante para orientar abordagens terapêuticas mais seletivas.

Zur Neuropsychologie und Neurophysiologie der Anorexia nervosa

Zusammenfassung. Theoretischer Hintergrund: Konvergierende neurowissenschaftliche Befunde zur Anorexia nervosa deuten darauf hin, dass Veränderungen im Zentralnervensystem mit Störungen des Essverhaltens assoziiert sein können. Fragestellung und Methode: Es soll ein Überblick über ausgewählte empirische Befunde aus den Bereichen Neuroanatomie, Neurophysiologie und Neuropsychologie gegeben werden. Ergebnisse und Schlussfolgerungen: Trotz der teilweise heterogenen Befundlage belegen die Ergebnisse, dass bei der Anorexie strukturelle und funktionelle cerebrale Veränderungen vorliegen können, denen möglicherweise eine Rolle bei der Genese und Aufrechterhaltung der Erkrankung zukommt.

Microstructure of eating behavior associated with Rorschach characteristics in obesity

The relationship between the microstructure of eating behavior and personality aspects according to the Rorschach Comprehensive System (Exner, 1991, 1993) was investigated among obese participants (N = 32). Eating behavior was measured using a computerized eating monitor, VIKTOR (Cabmek, Stockholm, Sweden), calculating initial eating rate and the eating curve. A higher initial eating rate reflecting eating drive was associated with Rorschach signs of stress overload according to the D Score and higher affective responsiveness to external stimuli seen in the Affective ratio. The stress overload may prompt eating, and affective responsiveness may be linked to appetite through a higher sensitivity to food stimuli, thus increasing eating drive. An accelerating rate of consumption during the meal was associated with intense emotionality and oral dependency, suggested by Pure C and Food responses.

Are there specific disabilities of number processing in adolescent patients with Anorexia nervosa? Evidence from clinical and neuropsychological data when compared to morphometric measures from magnetic resonance imaging

The cerebral effect of the loss of body weight in Anorexia nervosa (A.n.)--the so-called 'pseudoatrophy'-- is well known and confirmed by several neuroimaging studies. Another subject of intensive research has been whether A.n. leads to specific cognitive impairments, especially of intelligence. However, there are no previous studies on the relations between the cerebral changes, intelligence performance, and disorders of number processing in adolescent patients with A.n. We examined n = 18 inpatients with A.n. (means at admission: age 14.5 years, SD 1.59; BMI 14.9, SD 1.36), diagnosed according to ICD-10 criteria at three different timepoints: at admission to treatment (T1), with 50 % restoration of their normal weight (T2), and with normal weight (T3). At each timepoint, a cerebral MRI scan was obtained. Based on the MRI we determined the volume of the external and internal cerebrospinal fluid cavities, fissures of Sylvius, the surface of mesencephalon and pons, and surface and length of the Corpus callosum. At T1 and T3, a neuropsychological examination was conducted including tests of the general fluid ability and general cristallized ability of intelligence (CFT-20), as well as tests of vocabulary and number processing. The same instruments were given to a group of matched controls (means: age 15.8 years, SD 1.57; BMI 20.5, SD 2.3) at one timepoint. We could show a significant volume difference of the lateral ventricles and the fissure of Sylvius between patients at T, and controls, which abaded with the patient's weight restoration. But a significant surface deficit of the mesencephalon, and less pronounced in the pons, persisted to T3 in patients when compared to controls, suggesting a selectivity of the cerebral changes in A.n. The neuropsychological examinations revealed significant changes in test performance for both the general intelligence test and number processing. At T1 the number processing performance was significantly lower in patients when compared to controls. However, when the patients had restored their normal body weight, we found 2.02 % with a 'severe disorder of arithmetic skills' and 4.45 % with a 'functional disorder of arithmetic skills'. This combined prevalence of 6.47 % of patients with a subnormal arithmetic performance is analogous to that in the normal population.

[Haptic perception and EEG changes in anorexia nervosa]

OBJECTIVES

We predicted that due to diminished somatosensory integrative ability, the anorectic patients would have problems reproducing haptic stimuli. In addition we sought to determine whether EEGs from anorectic patients (AN) and the healthy controls (CO) would show discrepancies between the two groups during haptic explorations in theta-power over the right parietal region.

METHOD

EEG power (theta-power) data of AN (n = 13) and CO (n = 13) were analyzed during haptic exploration tasks and rest intervals. The haptic explorations consisted of palpating the structure of six sunken reliefs in sequence with both hands, eyes closed. After each exploration the structure was drawn on a piece of paper.

RESULTS

The reproductions of haptic stimuli submitted by the anorectic patients were of notably poorer quality than those of the healthy controls. During rest intervals and haptic explorations, spectral power was generally lower in the AN group in comparison to the healthy controls. Significant theta-power differences between groups showed over the right parietal cortex during haptic explorations. The decrease in EEG power in the anorectic patients in the theta bands across the right parietal region during haptic exploration tasks could be interpreted as a minor activation of visuo-spatial regions. The results of the haptic explorations as well as the EEG-power changes indicate a cortical dysfunction and deficits in somatosensory integration processing in anorexia nervosa patients.

Neuropsychological assessments before and after treatment in patients with anorexia nervosa and bulimia nervosa

In psychiatric patients the identification of cognitive deficits which predict a poor clinical outcome is important for the development of specific treatment strategies aimed at the amelioration of these impaired cognitive functions to increase the likelihood of full clinical remission. However, such attempts are absent in bulimia nervosa (BU), are scarce in anorexia nervosa (AN) and, furthermore, provide conflicting results. In the present prospective study we investigated the neuropsychological demands in 12 patients with AN and in 14 patients with BU before, during, and after a treatment period. At the initial testing session, both patients samples showed similar and impaired performance levels on tasks measuring attentional demands and problem solving abilities, while their mnemonic functions were preserved. At the final testing session, which took place 7 months thereafter, the impaired cognitive functions had improved to a similar degree in the AN and the BU subgroups. However, although the eating disorder symptomatology had ameliorated in parallel, no direct associations could be established with the initial neuropsychological demands and their rectification, respectively. On an individual level, 11 patients initially showed obvious cognitive deficits. However, the clinical characteristics of this subgroup differed not from that found in the 15 'good performers'. These findings indicate that the cognitive functions in the acute AN and BU are similarly impaired, but also ameliorate in a similar manner with clinical remission. Because no associations were obvious between cognitive and clinical rectifications, significant contributions of mediating factors (e.g., changes in metabolic brain turnover and in steroid hormones) are suggested.

Differential hemispheric involvement in anorexia nervosa

Hemispheric function was assessed in 22 restricting anorexia nervosa (AN) female subjects and 22 normal female controls. Two verbal and two visuospatial tasks and a set of psychopathological tests were administered. The failure of the "classic" lateralization tests to reveal the expected left hemisphere dominance or a right hemisphere deficit in AN group, as compared to controls, is counterbalanced by the tendency of the psychopathological tests to prove the neuropsychological hypothesis of the present study. Neuropsychological interpretation of psychopathological data, however, does not constitute direct evidence and so further studies and more sophisticated techniques are needed.

Assessment of brain function in adolescent anorexia nervosa before and after weight gain

This study assessed brain function in 20 adolescent females with anorexia nervosa (AN) and 20 controls using event-related potentials (ERPs) and a battery of neuropsychological tests. In the AN group, N4 latencies for a nonverbal memory task were significantly longer than for a verbal task, and P3 latencies for the verbal task were significantly longer among anorexics as compared to controls. On the nonverbal task, the AN group failed to show a right > left hemispheric asymmetry for P3 amplitudes which was observed for controls. These group differences for P3 latency and amplitude were particularly pronounced in the central-parietal region of the head. Body Mass Index (BMI) in the anorexic group significantly predicted N4 amplitudes for the verbal task in the left hemisphere and P3 amplitudes for the nonverbal task in the right hemisphere. The two groups did not differ on any of the tests used to assess neuropsychological functioning. Eight nutritionally recovered patients and their matched controls were retested using the same procedures. Anorexics showed larger P3 amplitudes for the verbal as compared to the nonverbal task at follow-up. These findings provide evidence for localized brain dysfunction in anorexia nervosa that only partially normalizes with weight gain.

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.

Cognition in eating disorders

Cognitive functions were investigated in four groups of women: 30 underweight anorexics, 38 normal-weight bulimics, 20 long-term weight-restored anorexics, and 39 normal controls. A MANOVA was used to examine performance on five neuropsychological domains derived from prior principal components analyses of a comprehensive neuropsychological battery. Underweight anorexics performed more poorly than normal controls in four of five neuropsychological domains (focusing/execution, verbal, memory, and visuospatial), while normal-weight bulimics showed poorer performances only in focusing/execution. The absolute differences in scores between eating disorder groups and normal controls were for the most part small, suggesting subtle rather than frank cognitive difficulties. Poorer neuropsychological test performance was associated with anxiety but not depression as measured by the Tryon, Stein, and Chu Tension scale and scale 2 of the MMPI respectively. The findings support previous reports of attentional difficulties in eating disorders but do not support the hypothesis of differential right-hemisphere dysfunction in eating disorders.

Neuropsychological test performance of bulimic patients

Thirty subjects with DSM-III diagnoses of bulimia were compared to 30 matched controls on the Luria-Nebraska Neuropsychological Battery. The bulimics showed poorer performance on tasks associated with functioning of the right frontal cortical area, primarily tasks involving speed of drawing geometric figures. The similarities of the findings to previous findings with anorexic samples and patients with affective disorders are discussed.