Françoise Biver

Frontal and parietal metabolic disturbances in unipolar depression

The authors investigated brain glucose utilization using positron emission tomography (PET) in 12 normal volunteers and 12 unipolar unmedicated depressed patients (six endogenous; six nonendogenous) following injection of [18F]fluoro-deoxyglucose (FDG). Compared by analyses of variance, absolute and relative regional glucose metabolic rates appeared different in depressed patients and control subjects, especially in parietal and frontal lobes. In patients with unipolar depression, metabolic rates were increased in the orbital part of the frontal lobe and decreased in a frontal dorsolateral area. The metabolic supero-basal gradient calculated in the frontal cortex was significantly lower in depressed patients than in normal subjects. Decreased glucose metabolism was also observed in the parietal cortex of depressed patients. No differences in glucose metabolic rates have been detected between endogenous and nonendogenous patients. No correlation has been found between the metabolic data and the Hamilton Rating Scale.

Sex difference in 5HT2 receptor in the living human brain

Serotonergic mechanisms are involved in gender-related behaviors and psychiatric conditions like aggression, eating disorders, depression, impulsivity or suicide. We studied gender differences in the living human brain type-2 serotonin receptor (5HT2r). Twenty-two healthy age-matched men and women were investigated using positron emission tomography and the selective radiotracer, 18F-labeled altanserin. Binding was quantified using a non-linear least-squares minimization procedure. We found significantly higher 5HT2r binding capacity in men than in women, especially in the frontal and cingulate cortices. Distinct liability for men and women to suffer from some psychiatric disorders responding to serotonergic agents may be related to differences in brain serotonin receptors.

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.

Altered frontostriatal relationship in unmedicated schizophrenic patients

Positron emission tomography with [18F]-fluoro-2-deoxy-D-glucose as tracer was used to investigate frontal glucose metabolism in 15 unmedicated schizophrenic patients and 15 healthy subjects under resting conditions. Although no difference in absolute frontal cerebral metabolic rates of glucose (CMRglu) were found between schizophrenic patients and control subjects, relative measures significantly differentiated the two groups. Whole frontal metabolism and frontocaudate ratio were significantly decreased in both hemispheres in the patients. The results confirm the existence of hypofrontality in unmedicated schizophrenia and indicate disturbances in metabolic relationships between the frontal cortex and the striatum in this disorder.

Brain hypometabolism of glucose in low-weight depressed patients and in anorectic patients: a consequence of starvation?

As low-weight anorectic patients presented a global as well as a regional absolute hypometabolism of glucose, we investigated a population of ten age- and sex-matched low-weight depressed patients without anorexia nervosa to evaluate the impact of weight loss on cerebral glucose metabolism evaluated by positron emission tomography and [18F]-fluorodeoxyglucose. Ten age- and sex-matched healthy volunteers were used as controls. Absolute global and regional glucose activity was significantly lower in anorectic and low weight depressed patients than in control subjects. Anorectic patients compared with normal control subjects also showed lower relative metabolism of glucose in the parietal cortex. Within patients, absolute hypometabolism of glucose seems to be a consequence of low-weight while there is a positive correlation between absolute metabolism of glucose and body mass index.

In vivo binding of [18F]altanserin to rat brain 5HT2 receptors: A film and electronic autoradiographic study

To further validate its use in positron emission tomography (PET), we studied the binding of [18F]altanserin, a specific 5HT2 radioligand, in the rat brain using in vivo autoradiography. Distribution of [18F]altanserin binding was comparable to the in vitro mapping of 5HT2 receptors reported in the literature. Selective displacers were used to test the reversibility and the selectivity of this radioligand. Specific binding of [18F]altanserin in the rat frontal cortex was quantified by direct counting with an electronic imaging system and by quantification on digitalized autoradiograms. Close results of about 30 pmol/g were obtained with both methods. Our data confirmed that [18F]altanserin is a valid tracer for 5HT2 receptors binding studies.

Temporal glucose metabolism in borderline personality disorder

The pathophysiology of borderline personality disorder (BPD) is obscure. Underlying organic factors such as epilepsy are suspected because clinical characteristics of the syndrome are similar to some manifestations of patients with complex partial seizures (CPS). Positron emission tomography (PET) with 18F-fluorodeoxyglucose (FDG) reveals hypometabolism in the area surrounding epileptic foci. To test the epilepsy hypothesis in BPD, we have explored 10 patients with BPD and compared them with 15 control subjects using PET with FDG. We conclude that PET provides no metabolic indication of temporal lobe epilepsy in BPD.

Changes in metabolism of cerebral glucose after stereotactic leukotomy for refractory obsessive-compulsive disorder: a case report.

Brain glucose metabolism was investigated with PET and [18F]fluorodeoxyglucose, before and after a bifrontal stereotactic leukotomy in a 37 year old woman with refractory obsessive-compulsive disorder. A bilateral decrease in glucose metabolism was found in the orbital frontal cortex after psychosurgery. Glucose metabolism was decreased to a lesser degree in Brodmanns area 25, in the thalamus, and in the caudate nucleus. Clinical improvement in obsessive-compulsive disorder after stereotactic tractotomy seems to be associated with metabolic changes in the brain, in particular, in the orbital part of the frontal lobe.

Basal ganglia and frontal lobe glucose metabolism. A reproducibility positron emission tomography study.

Positron emission tomography (PET) with 18F‐fluoro‐2‐deoxy‐Dglucose (FDG) is frequently used to study the metabolic correlates of movement and mental disorders. These studies generally focus on changes in the frontal cortex and the basal ganglia. The reproducibility of glucose metabolism estimates in these structures was tested in 13 normal subjects studied at rest usmg a standard and simple protocol. A reproducible dorsoventral metabolic gradient was demonstrated in the frontal cortex. Such a grad1ent was not present in the basal ganglia when the upper region of interest in the caudate nucleus, where the lower metabolic rate of glucose was probably attnbutable to partial volume effects, was not considered. Absolute values of glucose metabolic rates varied by 6.4 to 12.5% m the frontal cortex and by 6.8 to 14.7% in the basal ganglia. Vamtions in normalized values in the basal gangl1a ranged from 4.0 to 8.6%. The number of subjects required to detect statistical differences in group companson or in test‐retest studies was calculated for different anticipated levels of change. With the variability detected in this expenment, less than 10 subjects were expected to be sufficient to detect a 15% change in most regions and in both types of studies.

Interregional correlation of cerebral glucose metabolism in unmedicated schizophrenia

To investigate metabolic relationships between different brain regions in schizophrenia, we measured regional brain metabolism using positron emission tomography (PET) and [18F]fluorodeoxyglucose (FDG) in 15 unmedicated schizophrenic patients and 15 healthy subjects. We analyzed correlations between glucose metabolism data of multiple brain regions using factorial analysis and correlation coefficient comparisons. Absolute regional intercorrelations in schizophrenic brains were found to be significantly stronger than in controls, in relationship to the greater variability of metabolic rates in schizophrenic patients. Variability of normalized metabolic rates and regional intercorrelations were not significantly different between schizophrenic patients and control subjects. We conclude that a global metabolic factor accounts for the variability of metabolic data in untreated schizophrenia.