Publications by authors named "Jeffrey Chee Leong Looi"

White matter changes (WMC) are common magnetic resonance imaging (MRI) findings, particularly in the elderly. Recent studies such as the Leukoaraiosis and Disability Study (LADIS) have found that WMC relate to adverse outcomes including cognitive impairment, depression, disability, unsteadiness and falls in cross-sectional and follow-up studies. Frontostriatal (or frontosubcortical) brain circuits may serve many of these functions, with the caudate nuclei playing a role in convergence of cognitive functions.

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Niemann-Pick Type C disease (NPC) is a rare genetic disorder of lipid metabolism. A parameter related to horizontal saccadic peak velocity was one of the primary outcome measures in the clinical trial assessing miglustat as a treatment for NPC. Neuropathology is widespread in NPC, however, and could be expected to affect other saccadic parameters.

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Chorea-acanthocytosis (ChAc) is an uncommon autosomal recessive disorder due to mutations of the VPS13A gene, which encodes for the membrane protein chorein. ChAc presents with progressive limb and orobuccal chorea, but there is often a marked dysexecutive syndrome. ChAc may first present with neuropsychiatric disturbance such as obsessive-compulsive disorder (OCD), suggesting a particular role for disruption to striatal structures involved in non-motor frontostriatal loops, such as the head of the caudate nucleus.

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Frontostriatal circuit mediated cognitive dysfunction has been implicated in frontotemporal lobar degeneration (FTLD) and may differ across subtypes of FTLD. We manually segmented the neostriatum (caudate nucleus and putamen) in FTLD subtypes: behavioral variant frontotemporal dementia, FTD, n=12; semantic dementia, SD, n=13; and progressive non-fluent aphasia, PNFA, n=9); in comparison with controls (n=27). Diagnoses were based on international consensus criteria.

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The neuroacanthocytoses are a group of disorders characterised by peripheral blood acanthocytes, central nervous system as well as neuromuscular symptoms. These disorders uniformly result in pathology in the basal ganglia, which account for the characteristic motor symptoms such as chorea or dystonia, but may also account for the apparent elevated rates of major mental disorders in these syndromes. Elevated rates of dysexecutive syndromes, obsessive-compulsive disorder, depression and schizophrenia-like psychosis appear to occur in chorea-acanthocytosis, McLeod's syndrome, pantothenate kinase-associated neurodegeneration, and Huntington's disease-like 2.

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Background And Purpose: Frontostriatal circuit mediated cognitive dysfunction has been implicated in frontotemporal lobar degeneration (FTLD), but not Alzheimer's disease, or healthy aging. We measured the neostriatum (caudate nucleus and putamen) volume in FTLD (n=34), in comparison with controls (n=27) and Alzheimer's disease (AD, n=19) subjects.

Methods: Diagnoses were based on international consensus criteria.

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There is converging evidence of gray matter (GM) structural alterations in different limbic structures in Post-Traumatic Stress Disorder (PTSD) patients. The aim of this study was to evaluate GM density in PTSD in relation to trauma load, and to assess the GM differences between responders (R) and non-responders (NR) to EMDR therapy. Magnetic Resonance Imaging (MRI) scans of 21 subjects exposed to occupational trauma, who developed PTSD (S), and of 22 who did not (NS), were compared by means of an optimized Voxel-Based Morphometry (VBM) analysis as implemented in SPM.

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We aimed to assess the volume of the nucleus caudatus as a neuroanatomical substrate of fronto-subcortical circuits, in stroke patients with/without dementia, and the relationship to potential determinants of neural circuit integrity such as white matter hyperintensities (WMH) and stroke volume. Stroke only (Stroke) (n=19) and stroke with Vascular Dementia (VaD) (n=16) and healthy control (n=20) subjects, matched on demographic variables, underwent extensive neuropsychiatric assessments and manual MRI-based volumetric measurements for intracranial area (ICA), stroke volume, and bilateral caudate volume. WMH on MRI were quantified using an automated algorithm.

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The caudate nucleus is a structure implicated in the neural circuitry of psychological responses to trauma. This study aimed to quantify the volume of the caudate in persons exposed to trauma. Thirty-six subjects under 65 were recruited from transport workers in Stockholm who reported having been unintentionally responsible for a person-under-the-train accident or among employees having experienced an assault in their work (1999-2001) between 3 months and 6 years before MRI scanning.

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Our aim was to develop a reliable and valid manual segmentation protocol for tracing the caudate nucleus in MRI for volumetric and, potentially, shape analysis of the caudate. Using the protocol, two inter- and intra-rater reliability studies were conducted using five different raters on two different image analysis platforms (ANALYZE, Mayo Biomedical Imaging Resource, Rochester MN, USA, and HERMES, Nuclear Diagnostics AB, Stockholm, Sweden). Reference images for the detailed protocol are described.

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Objective: Authors investigated the nature of delayed-onset posttraumatic stress disorder (PTSD) among combat veterans.

Methods: PTSD, along with cognitive and emotional functioning, was assessed in a case series of elderly Australian war veterans.

Results: Fifteen elderly male subjects consecutively referred to an outpatient psychiatric clinic were identified as having PTSD with significantly delayed onset.

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