Local cerebral glucose metabolic rates in obsessive-compulsive disorder. A comparison with rates in unipolar depression and in normal controls

Quantitative comparison of measurements of cerebral glucose metabolic rate made with two positron cameras

The rapid progress in PET technology has created the dilemma of how to compare data from old and new tomographs. We examined cerebral metabolic data from two scanners, with different spatial resolutions and methods of attenuation correction, to see if metabolic values from the lower-resolution tomograph (ECAT II) could be adjusted to make them comparable to data from the higher-resolution scanner (Scanditronix PC1024-7B). Nine subjects were scanned on both tomographs after a single injection of [18F]2-fluoro-2-deoxy-D-glucose. Regional and lobar gray matter metabolic rates for glucose were obtained from comparable images from each scanner. Ratios of lobar to global gray matter metabolism also were calculated. Regression coefficients and percent differences were computed to compare ECAT II and PC1024 data. Two-thirds of the region pairs showed significant regressions, although percent differences were quite variable, with measures of glucose utilization ranging from 30 to 120% higher on the PC1024 compared to those from the ECAT II. Comparisons of lobar glucose rates between the two machines were less variable (50 to 80%), and ratios differed by only +/- 5% (except for the temporal ratios). Since there was no simple and consistent relationship between regional metabolic rates on the two tomographs, an overall adjustment of regional ECAT values for comparison to PC1024 values would be impossible. A region-by-region adjustment would be necessary. Lobar ratios are sufficiently similar that direct comparisons might be possible.

Positron emission tomography as a research tool in the investigation of psychiatric and psychological disorders

The principles of positron emission tomography (PET) are described, and illustrations of how these can be applied to clinical psychiatric questions relating to schizophrenia and depression are delineated. The metabolic changes in the frontal lobes which have been described in both depression and schizophrenia and depression are reviewed and discussed. More recent PET techniques allow several serial measurements of changes in regional blood flow in response to either a pharmacological challenge or a specific psychological task. This method provides a promising new approach to the study of the dopaminergic system in schizophrenia. New tracer methods of quantitating changes in in vivo concentrations of opioid receptors allow direct pharmacological access to the endogenous opioid system in the brain. Observations of regional cortical differences in opioid receptor concentration in relation to the medial and lateral pain systems are described. In addition, changes in receptor occupancy during sleep using [11C]diprenorphine and changes in the mu-specific tracer [11C]carfentanil in temporal lobe epilepsy are discussed.

Brain MRI in obsessive-compulsive disorder

Magnetic resonance imaging (MRI) brain scans were performed on 12 patients with obsessive-compulsive disorder and 12 healthy controls. Measurements of the area of the head of the caudate nucleus, cingulate gyrus thickness, intracaudate/frontal horn ratio, and area of the corpus callosum did not differ between the two groups. These limited data do not support the presence of a consistent gross brain structural abnormality in obsessive-compulsive disorder. Further studies using other anatomic measurements and other brain structural imaging techniques are warranted.

Positron emission tomography in the differential diagnosis of organic dementias

At present, PET is the only technology affording the quantitative, three-dimensional imaging of various aspects of brain function. Since function and metabolism are coupled, and since glucose is the dominant substrate of the brain's energy metabolism, studies of glucose metabolism by PET of 2(18F)-fluoro-2-deoxy-D-glucose (FDG) are widely applied for investigating the participation of various brain systems in simple or complex stimulations and tasks. In focal or diffuse disorders of the brain, functional impairment of affected or inactivated brain regions is a reproducible finding. While glucose metabolism is decreased slightly with age in a regionally different degree, in most types of dementia severe changes of glucose metabolism are observed. Degenerative dementia of the Alzheimer type is characterized by a metabolic disturbance most prominent in the parieto-occipito-temporal association cortex and later in the frontal lobe, while primary cortical areas, basal ganglia, thalamus, and cerebellum are not affected. By this typical pattern Alzheimer disease can be differentiated from other dementia syndromes, as e.g., Pick's disease (with the metabolic depression most prominent in the frontal and temporal lobe), multi infarct dementia (with multiple focal metabolic defects), and Huntington's chorea (with metabolic disturbance in the neostriatum). In demented patients PET studies can also be applied to the quantification of treatment effects on disturbed metabolism.

Serotonergic interhemispheric asymmetry: neurochemical and pharmaco-EEG evidence

1. Postmortem neurochemical investigations revealed interhemispheric asymmetry in the mediofrontal region of human brain. Significantly higher right hemisphere serotonin metabolite (5HIAA) content as well as increased maximal imipramine binding (IB) were found in the right hemisphere than in the left side. 2. IB did not show a gender difference in the mediofrontal area. However, women had higher IB in the right orbital frontal cortex than did men. 3. In vivo pharmaco-EEG results tend to support the postmortem neurochemical data. Intravenous chlorimipramine resulted in an asymmetric topographic distribution of the P300 auditory evoked potential, peak amplitudes were shifted to the right hemisphere.

Fluvoxamine treatment of coincident autistic disorder and obsessive-compulsive disorder: a case report

This is a single-case report of fluvoxamine treatment of comorbid autistic disorder (AD) and obsessive-compulsive disorder (OCD). Psychological, neuroanatomical, and neurochemical parallels are drawn between AD and OCD. The implications of this case of coincident AD and OCD, as well as the response to fluvoxamine, are discussed with respect to nosology, pathophysiology, and treatment of these disorders.

Integrated phylogeny of the primate brain, with special reference to humans and their diseases

Fossil, comparative anatomic and ontogenic data suggest that several systems of functionally and anatomically related brain regions underwent selective expansion or differentiation during primate evolution, according to the principle of 'integrated phylogeny'. This process was closely tied to expansion of the neocortex, particularly of its association areas. System I regions include the association neocortices as well as the nucleus basalis of Meynert, the entorhinal cortex, and subdivisions of the septum, hippocampal formation and amygdaloid complex. This system undergoes degeneration in Alzheimer's and Pick's diseases and Down syndrome. System II includes segregated circuits involving parts of the frontal cortex, basal ganglia, thalamus, and substantia nigra, and can become defective in obsessive-compulsive disorder, Huntington's and Parkinson's diseases. Certain nuclei in the mesencephalon and brainstem, which co-evolved with System I and II regions, also demonstrate pathology in diseases affecting these systems. Integrated phylogeny of each of these systems during primate evolution likely was promoted by regulatory mutations, gene duplications or chromosomal rearrangements. Thus, understanding the genetic basis of integrated phylogeny of systems of brain regions during primate evolution may elucidate the pathogenesis of the human diseases which affect these regions.

Obsessive-compulsive disorder: a clinical, neuropsychological and positron emission tomography study

The authors compared 16 nondepressed obsessive-compulsive patients (OCS) with 8 normal controls (NC) of similar age for resting-state regional cerebral glucose metabolic rates (rCMRglu) using positron emission tomography with the fluorodeoxyglucose method. OCS were rated for clinical data, and a neuropsychological battery was administered to 14 patients on the day of the scan. Absolute rCMRglu for whole cortex, and normalized prefrontal lateral cortex metabolic rates, were both significantly lower in OCS than in NC. No significant difference between treated (n = 10) and drug-free (n = 6) OCS was found for those variables. OCS were significantly impaired in the neuropsychological tasks assessing memory and attention. The rCMRglu for prefrontal lateral cortex were negatively correlated to Stroop-test subscores. This "frontal-oriented" task assessed the ability of OCS to inhibit immediate but inappropriate responses. These results suggest, in OCS, a modification of the general activating systems of cortical function and a relationship between the lateral prefrontal rCMRglu decrease and a selective attention deficit.

The case-control study in psychiatry

Case-control studies involve 'cases' being compared to 'controls' with respect to 'exposures', possible aetiological (or associated) factors. Associations between a disease and an exposure can be explained by chance, reverse causality, confounding and biases or, lastly, by causality. However, confounders as well as information and selection biases can be adjusted for at the design (or analysis) stage of the study. The strength of an association can be measured by means of relative risk, calculated indirectly using the odds ratio. Well conducted control studies should produce accurate estimates of relative risks in many psychiatric investigations.

Endogenous event-related potentials in obsessive-compulsive disorder

Brain event-related potentials (ERPs) were used to investigate central nervous system (CNS) correlates of cognitive function in obsessive-compulsive disorder (OCD). ERPs of 10 unmedicated OCD patients and 10 normal controls were measured in an auditory "oddball" task. Increasing task difficulty resulted in longer N200 and P300 latencies in normal subjects, but not in OCD patients. Moreover, OCD patients displayed shorter P300 latency than normal controls for the more difficult discrimination conditions. This replicates prior findings of Beech et al. (1983) for a visual task. For both levels of task difficulty, OCD patients also showed greater negativity than normal controls in the N200 region, which extended into the subsequent slow wave region. Negativities in the N200 and slow wave regions were larger at sites over the left hemisphere than the right hemisphere. The enhanced negativities and reduced P300 latency in OCD patients are discussed in terms of current theories postulating cortical hyperarousal and left hemisphere involvement in OCD.

Comparison of regional brain metabolism in bulimia nervosa and affective disorder assessed with positron emission tomography

Women with bulimia often present with symptoms of depression in addition to bingeing and purging behavior. Brain metabolism in eight women with bulimia nervosa was compared to that in eight women with major affective disorder and eight normal women, using positron emission tomography and 18-fluoro-2-deoxyglucose. Normal women have higher right than left cortical metabolic rates and active basal ganglia. Bulimics lost the normal right activation in some areas, but maintained basal ganglia activity. Depressives retained right hemisphere activation, but had decreased metabolism in basal ganglia. This suggests that although women with bulimia frequently present with symptoms of depression, the pathophysiologic changes associated with bulimia differ from major effective disorder.

Neurosurgical treatment of severe obsessive-compulsive disorder associated with Tourette's syndrome

We describe two patients with Gilles de la Tourette's syndrome (TS) and disabling obsessive-compulsive and ritualistic behaviors who underwent bilateral radiofrequency anterior cingulotomy. Both achieved a limited but sustained improvement in behavioral symptoms and overall functional abilities. Our observations indicate involvement of limbic structures in this disorder. The procedure should be considered for patients with TS complicated by resistant obsessive-compulsive disorder.

Obsessive-compulsive symptoms in childhood inflammatory bowel disease and cystic fibrosis

The Leyton Obsessional Inventory-Child Version was administered to 33 children with Crohn's disease, 11 with ulcerative colitis, and 46 with cystic fibrosis. Subjects with ulcerative colitis scored significantly higher on total number of obsessional symptoms and degree of resistance to symptoms than subjects with Crohn's disease. Scores of subjects with cystic fibrosis were intermediate between those of the ulcerative colitis and Crohn's disease groups. However, neither the ulcerative colitis group nor the Crohn's disease group differed significantly from the cystic fibrosis group that were statistically significant. Duration of illness was negatively correlated with symptoms in Crohn's disease and ulcerative colitis. The results suggest that obsessive-compulsive symptoms are not specific to Crohn's disease or ulcerative colitis and that obsessive-compulsive symptoms in pediatric chronic illness may be secondary to the demands of the illness.

Animal models of compulsive behavior

A convergence of clinical and pathological evidence points to the basal ganglia as the site of disturbance in compulsive disorders. However, the limbic system may be implicated as well. This article draws upon various lines of animal research in an attempt to explain how disturbances in one or another of these systems may produce compulsive behavior. Possible models include stimulation of the reinforcement mechanism, manipulation of the striatal "comparator" function, production and blockade of displacement behavior, and interference with the hippocampus' modulation of the stereotypy-inducing effect of reward. The common denominator of these models is a relative excess of dopaminergic activity in the basal ganglia. However, this does not necessarily implicate a primary dopaminergic disturbance in all human compulsive behavior.

Topographic evoked potential mapping in obsessive-compulsive disorder: evidence of frontal lobe dysfunction

Several lines of evidence suggest that frontal lobe dysfunction may underlie obsessive-compulsive disorder (OCD). Eighteen patients with OCD were compared with 18 normals matched for age, gender, handedness, and education on a Go-NoGo task. Visual evoked potentials were measured during the task. Topographic evoked potential mapping revealed significantly smaller P300 magnitudes in orbital frontal areas in the OCD patients. Results are compared with those from studies using other methodologies, and etiological implications are discussed.

Psychoanalysis and general psychiatry: obsessive-compulsive disorder as paradigm

To certain areas once dominated by psychoanalytic conceptualizations of psychopathology and pathogenesis, general psychiatry has in recent years made significant contributions. The obsessive-compulsive disorder is cited as an example, and illustrations of such contributions are described and discussed. Some implications for psychoanalytic theory and research are suggested.

Positron emission tomography of the brain

Positron emission tomography (PET) is a technique of transverse tomographic imaging in which detection of two photons emitted from the annihilation of a positron and an electron is used to reconstruct the distribution of a positron emitting isotope within an object. PET provides the capacity to quantitatively measure the local tissue distribution of a variety of radionuclides that are attached to compounds that distribute according to function. Although this technique has been used to measure multiple functions and receptors within the brain, one of the most widespread uses is the measurement of local cerebral glucose metabolism based on the deoxyglucose method. In this article, the application of PET to clinical disorders such as dementia, brain tumors, psychiatric disease, epilepsy, movement disorders, and stroke as well as to normal states such as aging are examined.

Obsessive-compulsive disorder: is there a frontal lobe dysfunction?

Obsessive-compulsive disorder has recently been found to be associated with various biochemical markers; this has revived interest in its biological basis. Most of the work to date has concentrated on the neurotransmitters involved. In this presentation, evidence from electrophysiological, neuropsychological, scan, lesion, and psychosurgical studies are integrated to focus on a possible frontal dysfunction in this disorder.

Brain imaging: applications in psychiatry

Various brain imaging techniques have become available in the past decade. These include techniques to evaluate brain structure, such as computed tomography and magnetic resonance imaging, and techniques to assess functional activity, such as measurement of regional cerebral blood flow, single photon emission computed tomography, and positron emission tomography. These techniques can be used to map brain structure and function in normal human beings, and they have enlarged our knowledge of the pathophysiology of mental illnesses by demonstrating structural, metabolic, and neurochemical abnormalities in a wide range of mental disorders.

Selective subcortical abnormalities in autism

Nine physically healthy, adult autistic men, with normal or near normal intelligence, and 13 healthy male controls were examined in a CT brain scan study. CT scans were analysed with a fully automated computer-assisted program, and regional brain radiodensities were measured with careful attention to artefacts. Autistic patients revealed significantly larger third, but not lateral, ventricular size and significantly lower mean caudate, but equivalent mean frontal and thalamic, radiodensities compared to controls. The sizes of the Sylvian fissures and interhemispheric fissure were equivalent between groups. The findings are consistent with selective subcortical abnormalities in autism.