Bipolar disorders

Bipolar disorder is characterized by (hypo)manic episodes and depressive episodes which alternate with euthymic periods. It causes serious disability with poor outcome, increased suicidality risk, and significant societal costs. This chapter describes the findings of the PET/SPECT research efforts and the current ideas on the pathophysiology of bipolar disorder. First, the cerebral blood flow and cerebral metabolism findings in the prefrontal cortex, limbic system, subcortical structures, and other brain regions are discussed, followed by an overview of the corticolimbic theory of mood disorders that explains these observations. Second, the neurotransmitter studies are discussed. The serotonin transporter alterations are described, and the variation in study results is explained, followed by an overview of the results of the various dopamine receptor and transporter molecules studies, taking into account also the relation to psychosis. Third, a concise overview is given of dominant bipolar disorder pathophysiological models, proposing starting points for future molecular imaging studies. Finally, the most important conclusions are summarized, followed by remarks about the observed molecular imaging study designs specific for bipolar disorder.</p

Changes in regional cerebral blood flow demonstrated by Tc-99m-HMPAO

Single photon emission computed tomography (SPECT) with Tc-99m-HMPAO was used to compare regional cerebral blood flow (rCBF) in patients with bipolar disorder and in healthy controls. The sample of this study consisted of 16 euthymic bipolar patients who met the DSM-IV criteria and 10 healthy control subjects. The mean regional cerebral blood flow values of the bipolar euthymic patients were significantly lower than those of the controls in the bilateral medial-basal temporal, occipital; medial frontal; parietal regions and in the cingulate gyrus; the hypoperfusion in the cingulate had the highest significant P value (.001, Bonferroni correction). No significant differences in rCBF emerged between right and left-brain regions. The most important findings of the current study are the presence of regional cerebral perfusion alterations, particularly in the cingulate gyrus in the euthymic bipolar patients. Our results imply that underlying brain dysfunction may be independent from manic or depressive episodes in bipolar disorder. Because of the small number of subjects, however, this finding should be viewed as preliminary

Changes in regional cerebral blood flow demonstrated by 99mTc-HMPAO SPECT in euthymic bipolar patients.

Single photon emission computed tomography (SPECT) with 99mTc-HMPAO was used to compare regional cerebral blood flow (rCBF) in patients with bipolar disorder and in healthy controls. The sample of this study consisted of 16 euthymic bipolar patients who met the DSM-IV criteria and 10 healthy control subjects. The mean regional cerebral blood flow values of the bipolar euthymic patients were significantly lower than those of the controls in the bilateral medial-basal temporal, occipital; medial frontal; parietal regions and in the cingulate gyrus; the hypoperfusion in the cingulate had the highest significant P value (.001, Bonferroni correction). No significant differences in rCBF emerged between right and left-brain regions. The most important findings of the current study are the presence of regional cerebral perfusion alterations, particularly in the cingulate gyrus in the euthymic bipolar patients. Our results imply that underlying brain dysfunction may be independent from manic or depressive episodes in bipolar disorder. Because of the small number of subjects, however, this finding should be viewed as preliminary

ARTIFICIAL INTELLIGENCE APPROACH TO CLASSIFY UNIPOLAR and BIPOLAR DEPRESSIVE DISORDERS

Machine learning (ML) approaches for medical decision making processes are valuable when both high classification accuracy and less feature requirements are satisfied. Artificial neural networks (ANNs) successfully meet the first goal with its adaptive engine while nature inspired algorithms are focusing on the feature selection (FS) process in order to eliminate less informative and less discriminant features. Besides engineering applications of ANN and FS algorithms, medical informatics is another emerging field using similar methods for medical data processing. Classification of psychiatric disorders is one of major focus of medical informatics using artificial intelligence approaches. Being one of the most debilitating psychiatric diseases, bipolar disorder (BD) is frequently misdiagnosed as unipolar disorder (UD), leading to suboptimal treatment and poor outcomes. Thus, discriminating UD and BD at earlier stages of illness could therefore help to facilitate efficient and specific treatment. The use of quantitative electroencephalography (EEG) cordance as a biomarker has greatly enhanced the clinical utility of EEG in psychiatric and neurological subjects. In this context, the paper puts forward a study using two-step hybridized methodology, particle swarm optimization (PSO) algorithm for feature selection process and ANN for training process. The noteworthy performance of ANN-PSO approach stated that it is possible to discriminate 31 bipolar and 58 unipolar subjects using selected features from alpha and theta frequency bands with 89.89% overall classification accurac

Bipolar Disorders

PET and SPECT in Psychiatry showcases the combined expertise of renowned authors whose dedication to the investigation of psychiatric disease through nuclear medicine technology has achieved international recognition. The classical psychiatric disorders as well as other subjects – such as suicide, sleep, eating disorders, and autism – are discussed and the latest results in functional neuroimaging are detailed. Most chapters are written jointly by a clinical psychiatrist and a nuclear medicine expert to ensure a multidisciplinary approach. This state of the art compendium will be valuable to all who have an interest in the field of neuroscience, from the psychiatrist and the radiologist/nuclear medicine specialist to the interested general practitioner and cognitive psychologist. It is the first volume of a trilogy on PET and SPECT imaging in the neurosciences; other volumes will focus on PET and SPECT in neurology and PET and SPECT of neurobiological systems

Neurobiological trait abnormalities in bipolar disorder

Dissecting trait neurobiological abnormalities in bipolar disorder ( BD) from those characterizing episodes of mood disturbance will help elucidate the aetiopathogenesis of the illness. This selective review highlights the immunological, neuroendocrinological, molecular biological and neuroimaging abnormalities characteristic of BD, with a focus on those likely to reflect trait abnormalities by virtue of their presence in euthymic patients or in unaffected relatives of patients at high genetic liability for illness. Trait neurobiological abnormalities of BD include heightened pro-inflammatory function and hypothalamic-pituitary-adrenal axis dysfunction. Dysfunction in the intracellular signal transduction pathway is indicated by elevated protein kinase A activity and altered intracellular calcium signalling. Consistent neuroimaging abnormalities include the presence of ventricular enlargement and white matter abnormalities in patients with BD, which may represent intermediate phenotypes of illness. In addition, spectroscopy studies indicate reduced prefrontal cerebral N-acetylaspartate and phosphomonoester concentrations. Functional neuroimaging studies of euthymic patients implicate inherently impaired neural networks subserving emotional regulation, including anterior limbic, ventral and dorsal prefrontal regions. Despite heterogeneous samples and conflicting findings pervading the literature, there is accumulating evidence for the existence of neurobiological trait abnormalities in BD at various scales of investigation. The aetiopathogenesis of BD will be better elucidated by future clinical research studies, which investigate larger and more homogenous samples and employ a longitudinal design to dissect neurobiological abnormalities that are underlying traits of the illness from those related to episodes of mood exacerbation or pharmacological treatment. Molecular Psychiatry (2009) 14, 833-846; doi:10.1038/mp.2009.39; published online 19 May 200