Caudate nucleus abnormalities in obsessive-compulsive disorder: measurements of MRI signal intensity

Diffusion-Weighted MRI Findings of Caudate Nucleus and Putamen in Patients With Obsessive-Compulsive Disorder

Objective The purpose of this study was to establish the diffusion-weighted magnetic resonance imaging (DW-MRI) findings of the caudate nucleus and putamen in patients with obsessive-compulsive disorder (OCD) and to obtain new information on the etiopathogenesis of OCD, which is still unclear. Methods The study comprised 20 patients with OCDs and 20 healthy volunteers. In these cases, DW-MRI and diffusion-weighted echo-planar images (DW-EPI) at b600 and b1000 gradient values were taken and the measurements were made using the apparent diffusion coefficient (ADC) maps of each group at b600 and b1000 values from the caudate nucleus and putamen. Results When the DW-MRI examination in patients with OCD was compared with the control group, the mean ADC values in the caudate nucleus and putamen were not found to have statistically significantly changed. In addition, there were no significant differences regarding the right and left caudate nuclei and putamen ADC values at the b600 and b1000 in the patients with OCD or the control group. Conclusion There are still many unknowns about the neurobiology of OCD. When the DW-MRI examination of the patients with OCD was compared with the control group in our study, no significant difference was found between the ADC values of the caudate nucleus and putamen. Further studies are required for this present study on DW-MRI in patients with OCD to be meaningful.

The anterior limb of the internal capsule: Anatomy, function, and dysfunction

The last two decades have seen a re-emergence of neurosurgery for severe, refractory psychiatric diseases, largely due to the advent of more precise and safe operative techniques. Nevertheless, the optimal targets for these surgeries remain a matter of debate, and are often grandfathered from experiences in the late 20th century. To better explore the rationale for one target in particular - the anterior limb of the internal capsule (ALIC) - we comprehensively reviewed all available literature on its role in the pathophysiology and treatment of mental illness. We first provide an overview of its functional anatomy, followed by a discussion on its role in several prevalent psychiatric diseases. Given its structural integration into the limbic system and involvement in a number of cognitive and emotional processes, the ALIC is a robust target for surgical treatment of refractory psychiatric diseases. The advent of novel neuroimaging techniques, coupled with image-guided therapeutics and neuromodulatory treatments, will continue to enable study on the ALIC in mental illness.

Executive functions in obsessive-compulsive disorder: An activation likelihood estimate meta-analysis of fMRI studies

OBJECTIVES

To identify activation changes assessed in functional magnetic resonance imaging (fMRI) studies of obsessive-compulsive disorder (OCD) through Activation Likelihood Estimate meta-analysis.

METHODS

We included 28 peer-reviewed standard stereotactic space studies assessing adult OCD patients (OCDpts) vs. healthy controls (HCs) with fMRI during executive task performance.

RESULTS

In within-group analyses, HCs showed task-related activations in bilateral inferior frontal gyri, right middle frontal gyrus, right inferior parietal lobule, right claustrum, bilateral cingulate gyri, and left caudate body. OCDpts showed task-related left-sided activations in the superior, medial, and inferior frontal gyri, and thalamus, and bilateral activations in the middle frontal gyri, inferior parietal lobule, and insular cortices. Subtraction analysis showed increased left middle frontal gyrus activation in OCDpts. In between-groups analyses, OCDpts hypoactivated the right caudate body, left putamen, left ACC, and right medial and middle frontal gyri. Right caudate hypoactivation persisted also after applying Family-wise error algorithms.

CONCLUSIONS

This meta-analysis confirms that during executive functioning OCDpts show a functional deficit of the right caudate body, which could represent a major neural functional correlate of their illness.

Pathogenetic and therapeutic perspectives on neurocognitive models in psychiatry: A synthesis of behavioral, brain imaging, and biological studies

Neurocognitive assessments are useful to determine the locus of insult as well as functional capacities of patients on treatment. In psychiatry, neurocognitive assessment is useful in the identification of brain lesions, evaluation of cognitive deterioration over time, and advancement of theories regarding the neuroanatomical localization of symptoms. Neurocognitive models provide a bridging link between brain pathology and phenomenology. They provide a useful framework to understand the pathogenesis of psychiatric disorders, bringing together isolated findings in behavioral, neuroimaging, and other neurobiological studies. This review will discuss neurocognitive model of three disorders - schizophrenia, bipolar disorder, and obsessive compulsive disorder - by incorporating findings from neurocognitive, neuroimaging, and other biological studies.

Morphometric magnetic resonance imaging in psychiatry

Although advances in the clinical criteria of various axis I psychiatric disorders are continually being made, there is still considerable overlap in the clinical features, and diagnosis is often challenging. As a result, there has been substantial interest in using morphometric magnetic resonance imaging to better characterize these diseases and inform diagnosis. Region of interest and voxel-based morphometry studies are reviewed herein to examine the extent to which these goals are being met across various psychiatric disorders. It is concluded based on the studies reviewed that specific patterns of regional loss, although present in certain axis I disorders, are not, as yet, diagnostically useful. However, advances in outcome and treatment monitoring show considerably more promise for rapid application in psychiatry.

Attention and cognition in patients with obsessive-compulsive disorder

Although a dysfunctional prefrontal-striatal system is presupposed in obsessive-compulsive disorder (OCD), this is not sustained by neuropsychological studies. The aim of this study was twofold: (i) to investigate the cognitive deficits in patients with OCD compared to matched healthy controls; and (ii) to relate cognitive performance to clinical characteristics in patients with OCD. In this study, 39 patients with primary OCD according to Diagnostic and Statistical Manual, fourth edition criteria were compared to 26 healthy control subjects on a battery measuring verbal memory and executive functioning. Patients with OCD showed slowed learning on the verbal memory task and made more errors on the Wisconsin Card Sorting Test. Errors were failures to maintain set, which were related to severity of OCD symptomatology. The results show that patients with OCD have cognitive deficits. The authors hypothesize that these deficits may be interpreted by attentional deficits caused by a dysfunctional anterior cingulate cortex.

Magnetic resonance imaging in patients with obsessive-compulsive disorder with good versus poor insight

The DSM-IV provides two subtypes of obsessive-compulsive disorder (OCD), labelled as OCD with insight and OCD with poor insight. For the latter, patients generally fail to recognize that the obsessions or compulsions are excessive or unreasonable. Several studies have shown significant brain abnormalities in OCD patients. However, at present, it remains unclear whether a specific pattern of structural brain abnormalities is related to poor insight in OCD. In the present study, magnetic resonance imaging (MRI) findings were compared in OCD patients with insight versus those with poor insight. Outpatients with diagnoses of OCD according to DSM-IV (300.30) and ICD-10 (F42) (n = 84; mean age 38+/-13; 35 females, 49 males) were dichotomized into the two subtypes. All subjects underwent an MRI examination. MRI findings were rated as "MRI abnormality" and "normal MRI." In our sample, 48% of the patients had MRI abnormalities. There was a highly significant difference between the two groups according to frequencies of MRI abnormalities, with 83% of the patients with poor insight showing MRI abnormalities compared with only 21% of the patients with insight. The specifier "poor insight" helps to identify a subgroup of OCD with a higher frequency of brain abnormalities of various types. This distinction should be taken into account in future studies concerning the course and therapeutic outcome of OCD.

The neuropsychology of obsessive compulsive disorder: the importance of failures in cognitive and behavioural inhibition as candidate endophenotypic markers

Obsessive compulsive disorder (OCD) is a highly debilitating neuropsychiatric condition with estimated lifetime prevalence of 2-3%, more than twice that of schizophrenia. However, in contrast to other neuropsychiatric conditions of a comparable or lesser prevalence, relatively little is understood about the aetiology, neural substrates and cognitive profile of OCD. Despite strong evidence for OCD being familial, with risk to first-degree relatives much greater than for the background population, its genetic underpinnings have not yet been adequately delineated. Although cognitive dysfunction is evident in the everyday behaviour of OCD sufferers and is central to contemporary psychological models, theory-based studies of neurocognitive function have yet to reveal a reliable cognitive signature, and interpretation has often been confounded by failures to control for co-morbidities. The neuroimaging findings in OCD are amongst the most robust reported in the psychiatric literature, with structural and functional abnormalities frequently reported in orbitofrontal cortex, anterior cingulate cortex, and caudate nucleus. In spite of this, our relative lack of understanding of OCD neurochemical processes continues to impede progress in the development of novel pharmacological treatment approaches. Integrating the neurobiological, cognitive, and clinical findings, we propose that OCD might usefully be conceptualised in terms of lateral orbitofrontal loop dysfunction, and that failures in cognitive and behavioural inhibitory processes appear to underlie many of the symptoms and neurocognitive findings. We highlight existing limitations in the literature, and the potential utility of endophenotypes in overcoming these limitations. We propose that neurocognitive indices of inhibitory functions may represent a useful heuristic in the search for endophenotypes in OCD. This has direct implications not only for OCD but also for putative obsessive-compulsive spectrum conditions including attention deficit hyperactivity disorder, Tourette's syndrome, and trichotillomania (compulsive hair pulling).

Quantitative Signal Intensity Measures on Magnetic Resonance Imaging in Attention-Deficit Hyperactivity Disorder

OBJECTIVE

The aim of this study was to investigate possible abnormalities of cerebral myelination in subjects with attention-deficit hyperactivity disorder (ADHD).

BACKGROUND

Anatomic and functional neuroimaging studies of subjects with ADHD demonstrated a right frontostriatal deficit and abnormal cerebral asymmetries. Some also reported white matter abnormalities, such as smaller white matter volumes in the right anterior-superior frontal region, and the smaller bilateral retrocallosal region. Smaller volumes in specific areas of the corpus callosum have also been reported. We hypothesized that white matter signal intensities may also show differences indicating abnormal cerebral myelination.

METHOD

We analyzed T2-weighted magnetic resonance images of 11 adolescents with ADHD and 20 controls. Regions of interest were set in both the white and gray matter in frontal and parieto-occipital associative regions.

RESULTS

The ADHD group showed a higher signal intensity ratio, probably reflecting a higher degree of myelination. Significant interhemispheric differences emerged only in the posterior region in the ADHD group.

CONCLUSIONS

The higher degree of myelination in the right frontal region of ADHD may be due to a compensatory mechanism for the right frontostriatal dysfunction.

Tc-99m HMPAO brain perfusion SPECT in drug-free obsessive-compulsive patients without depression

The aim of this study was to confirm prior results of brain-imaging studies on obsessive-compulsive disorder (OCD) in a sample of Turkish patients, as a cross-cultural study. Tc-99m HMPAO brain perfusion SPECT imaging was performed in nine drug-free OCD patients without depression and six controls. The patients' Hamilton Depression Rating Scale scores were <16. The severity of obsessive-compulsive symptoms was rated with the Yale-Brown Obsessive-Compulsive Rating Scale (YBOCS). Quantitative evaluation of regional cerebral blood flow revealed that right thalamus, left frontotemporal cortex and bilateral orbitofrontal cortex showed significant hyperperfusion in patients with OCD compared with controls. YBOCS scores did not show any correlation with hyperperfusion in regional cerebral blood flow in these areas. Results of this cross-cultural study may support orbitofrontal and thalamic dysfunction in OCD in a sample of Turkish patients.

Functional brain imaging in neuropsychiatric disorders of childhood

This review article presents a summary of the current state-of-the-art of functional brain imaging, with a primary focus on childhood neuropsychiatric disorders. Coverage is emphasized for developments that appear to be of current or potential future importance for the child neurologist and related pediatric specialist, and also from the perspective of the developmental neuroscientist. Emphasis is placed on the modalities of single photon emission computed tomography (SPECT), positron emission tomography (PET), and both "conventional" and "functional" magnetic resonance imaging, (MRI) including reference to the major new radiopharmaceutical and magnetic resonance-based imaging agents and techniques. The fundamental physicochemical processes underlying such studies are outlined, with citation of sources of more detailed information for the interested reader. A variety of imaging studies are reviewed for selected groups of childhood neuropsychiatric disorders, designed to illustrate the achievements and future promise of these imaging modalities. Areas of concentration are suggested for future imaging research in the field of childhood behavioral disorders, where these methods seem critical to improved understanding of pathogenetic mechanisms, as well as development of more effective treatment strategies.

Frontal lobe psychopathology: mania, depression, confabulation, catatonia, perseveration, obsessive compulsions, and schizophrenia

The frontal lobes can be subdivided into major functional neuroanatomical domains, which, when injured, surgically destroyed, or reduced in activity or volume, give rise to signature pathological and psychiatric symptomology. A review of case reports and over 50 years of research, including magnetic resonance imaging, positron emission tomography, and single photon emission computed tomography scans, indicates that apathy, "blunted" schizophrenia, major depression, and aphasic-perseverative disturbance of speech and thought are associated with left lateral as well as bilateral frontal (and striatal) abnormalities. Impulsiveness, confabulatory verbosity, grandiosity, increased sexuality, and mania are associated with right frontal (as well as bilateral) disturbances. Gegenhalten, catatonia, and disturbances of "will" are indicative of medial frontal injuries. Disinhibitory states and obsessive-compulsive perseverative abnormalities are more frequently observed with orbital frontal lobe dysfunction, including frontal-striatal disturbances. These associations, however, are not always clear-cut as patients with the same diagnosis may demonstrate different symptoms that may be due to an additional abnormality in a different region of the brain. Moreover, as the frontal subdivisions are richly interconnected, and as frontal lobe abnormalities are not always discrete or well localized, a wide array of seemingly divergent waxing and waning symptoms may be manifest, sometimes simultaneously, including manic depression and what has been referred to as the "frontal lobe personality."

Neuroimaging in child and adolescent neuropsychiatric disorders

OBJECTIVE

To review the major findings and pathophysiological implications of imaging studies of neuropsychiatric disorders that onset in childhood or adolescence.

METHOD

More than 200 neuroimaging studies were selected for review from Medline searches if the studies concerned developmental neuropsychiatric disorders such as autism, fragile X syndrome, Down syndrome, schizophrenia, obsessive-compulsive disorder, Tourette's syndrome, attention-deficit hyperactivity disorder, and dyslexia.

RESULTS

Disordered central nervous system development may produce evidence of cortical neuronal migration abnormalities in autism, smaller cortical structures in Down syndrome, frontal lobe deficits and larger basal ganglia in schizophrenia, hypoplastic basal ganglia in Tourette's syndrome, aberrancies of the planum temporale in dyslexia, and hypoplastic cerebellar structures in numerous developmental disorders. Normal cerebral asymmetries appear to be disrupted in a number of disorders, including schizophrenia, Tourette's syndrome, attention deficit disorder, and dyslexia.

CONCLUSIONS

Neuroimaging data regarding pathological central nervous system development in childhood are still sparse, and many of the findings in developmental disorders of childhood onset concern the study of adult subjects with those disorders. Nevertheless, imaging modalities previously used only in adults are with increasing frequency being applied to the study of children, which will likely continue to contribute to the understanding of pathological brain structure and function throughout childhood and to the improved treatment of these disorders.