Positron emission tomographic study of affective disorders: Problems and strategies

Abstract

Because anatomical studies of psychiatric disorders in humans have been largely unsuccessful, and because pharmacological interventions in patients with mental illness can be analyzed by means of biochemical assay techniques, positron emission tomography (PET) provides an exciting new means to study mental illness. Using fluorine-18-labeled fluorodeoxyglucose and PET to measure local cerebral glucose utilization, the investigators examined patients with affective disorders and normal age-matched controls. Patients with unipolar depression were studied in a drug-free baseline state following short-term administration of methylphenidate and in a euthymic state in long-term follow-up. Patients with bipolar disorders were studied in either the manic or depressed phases of illness and again in a euthymic state in long-term follow-up. Age-matched controls were studied both with and without methylphenidate administration. The results demonstrate that metabolic subgrouping of patients may be possible. Mood changes produced by pharmacological agents resulted in changes in the patterns of metabolism when compared with the baseline state. Problems associated with the use of PET to study mental illness fall into the categories of patient classification (diagnosis, state, trait, ambient conditions, and mental processes) and data analysis (anatomical and statistical). These problems, the limitations of the present techniques, and strategies for their improvement are discussed. Despite these difficulties, PET should prove to be a fruitful means of exploring the human biochemical abnormalities associated with mental illness.

Mesial temporal cortex hypoperfusion is associated with depression in subcortical stroke.

“…However, frontal and temporal glucose hypometabolism has been observed in major depression and in depression associated with other neurological diseases, using positron emission tomography. 29 - 30 In primary depression some authors found metabolic abnormalities involving both frontal and temporal cortices, 31 whereas others described glucose hypometabolism in either temporal 32 or frontal cortices. These previous observations, combined with the results of our study, suggest that interruption of pathways linking specific mesial temporal lobe regions may underlie depressive phenomenology.…”

Reduction of Prefrontal Cortex Glucose Metabolism Common to Three Types of Depression

“…depressions are severe illnesses that may afflict 2% to 4% of the general population at any time1"2 and 4% to7% ofthe general population over the course of a lifetime.3 In addition to the nonspecific, subjective experience of unhappiness, these medical depressions are characterized by and distinguished from ordinary sadness or demoralization by substantial disturbances of sleep, appetite, sexual function, cognition, and (of most concern) suicidal behavior.4 Further¬ more, the natural course of depressive mood disorders is one of alternations between states of illness and overt health,5 occa¬ sionally to the point of rapid, clocklike cycling of mood with little relation to external events.6,7 Besides occurring as primary affective disorders, with or without episodes ofmania ("bipolar" and "unipolar" depressions,6,8 respectively), the symptoms of major depression are known to complicate other psychiatric disorders as "secondary" disturbances-notably in obsessive-compulsive disorder (OCD) 21.8 ±6.6 (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32) 30.5 ±7.0 (20-43) 43±10 (33-61) OCD-no major depression 14 33.8±10.6 9.3±4.1 (2-16) 29 Bipolar Manic-Phase Subjects.-There were two women and four men, none ofwhom were included in the bipolar depressed-phase group described above. All but one had previous episodes of severe depression.…”

Indications for Differential Diagnosis of Nontumor Central Nervous System Diseases from Tumors

“…Recently, positron emission tomography (PET) has been j applied to the brain, and can image nontumor CNS diseases [1][2][3][4][5][6][7][8] and brain tumors [9][10][11][12][13] from hemodynamic and met abolic points of view using various tracers including recep-1 tors. In clinical practice, the 18F-fluorodeoxyglucose (FDG)-.…”