Investigation of Brain Iron in Niemann-Pick Type C: A 7T Quantitative Susceptibility Mapping Study.

BACKGROUND AND PURPOSE: While brain iron dysregulation has been observed in several neurodegenerative disorders, its association with the progressive neurodegeneration in Niemann-Pick type C is unknown. Systemic iron abnormalities have been reported in patients with Niemann-Pick type C and in animal models of Niemann-Pick type C. In this study, we examined brain iron using quantitative susceptibility mapping MR imaging in individuals with Niemann-Pick type C compared with healthy controls. MATERIALS AND METHODS: A cohort of 10 patients with adolescent- and adult-onset Niemann-Pick type C and 14 age- and sex-matched healthy controls underwent 7T brain MR imaging with T1 and quantitative susceptibility mapping acquisitions. A probing whole-brain voxelwise comparison of quantitative susceptibility mapping between groups was conducted. Mean quantitative susceptibility mapping in the ROIs (thalamus, hippocampus, putamen, caudate nucleus, and globus pallidus) was further compared. The correlations between regional volume, quantitative susceptibility mapping values, and clinical features, which included disease severity on the Iturriaga scale, cognitive function, and the Social and Occupational Functioning Assessment Scale, were explored as secondary analyses. RESULTS: We observed lower volume in the thalamus and voxel clusters of higher quantitative susceptibility mapping in the pulvinar nuclei bilaterally in patients with Niemann-Pick type C compared with the control group. In patients with Niemann-Pick type C, higher quantitative susceptibility mapping in the pulvinar nucleus clusters correlated with lower volume of the thalamus on both sides. Moreover, higher quantitative susceptibility mapping in the right pulvinar cluster was associated with greater disease severity. CONCLUSIONS: Our findings suggest iron deposition in the pulvinar nucleus in Niemann-Pick type C disease, which is associated with thalamic atrophy and disease severity. This preliminary evidence supports the link between iron and neurodegeneration in Niemann-Pick type C, in line with existing literature on other neurodegenerative disorders.

Cerebrospinal fluid neurofilament light predicts the rate of executive function decline in younger-onset dementia.

INTRODUCTION: Determining disease severity and predicting prognosis in younger onset-dementia (YOD) remains challenging. Whether CSF biomarkers neurofilament light (NfL), tau and amyloidß 42 (Aß42) can help provide such information has been underexplored. METHODS: Patients with YOD and CSF analysis were identified. We compared baseline NfL, tau and Aß42 concentrations with contemporaneous Neuropsychiatry Unit Cognitive Assessment Tool (NUCOG) scores to assess their association with severity of cognitive impairment. Cognitive decline, as measured by longitudinal NUCOG assessment, was correlated against baseline biomarker levels to assess their utility in predicting the rate of cognitive decline. RESULTS: 78 patients with YOD (mean age = 56 years, SD = 8) and CSF analysis were identified. Dementia types included Alzheimer's disease, behavioural variant frontotemporal dementia, dementia not-otherwise-specified and other. Tau was associated with contemporaneous memory dysfunction (r = -0.556, 95% CI:[-0.702,-0.393], p < .001). 21 patients had longitudinal cognitive assessment up to 82 months from CSF sampling. NfL was associated with the rate of executive function decline (r = 0.755, 95% CI:[0.259,0.937], p < .001). Aß42 was associated with the rate of memory decline (r = -0.582, 95% CI:[-0.855,-0.274], p = .007) and rate of total NUCOG decline (r = -0.515, 95% CI: [-0.809, -0.227], p = .017). CONCLUSION: CSF tau is related to contemporaneous memory impairment in YOD. NfL and Aß42 levels are associated with the rate of executive function and memory decline, respectively, and may have a role in prognostication in YOD.

Distinguishing Neuroimaging Features in Patients Presenting with Visual Hallucinations.

Visual hallucinations are relatively uncommon presentations in medical and psychiatric clinics, where they are generally regarded as a marker of possible underlying "organic" brain disease. Thus, patients with visual hallucinations are often referred for imaging of the brain. This article presents a pragmatic approach for the radiologist reviewing such imaging. Because conditions that can present with visual hallucinations are legion, a familiarity with the features of the hallucinations themselves, which can serve as clues to the underlying cause, can be helpful in interpreting such cases. We consider the nature of visual hallucinations and the mechanisms underlying their formation. We then provide a framework to guide the search for their cause, first in terms of focal lesions along the visual pathway and then global conditions affecting >1 region.

Striatal morphology as a biomarker in neurodegenerative disease.

The striatum, comprising the caudate nucleus, putamen and nucleus accumbens, occupies a strategic location within cortico-striato-pallido-thalamic-cortical (corticostriatal) re-entrant neural circuits. Striatal neurodevelopment is precisely determined by phylogenetically conserved homeobox genes. Consisting primarily of medium spiny neurons, the striatum is strictly topographically organized based on cortical afferents and efferents. Particular corticostriatal neural circuits are considered to subserve certain domains of cognition, emotion and behaviour. Thus, the striatum may serve as a map of structural change in the cortical afferent pathways owing to deafferentation or neuroplasticity, and conversely, structural change in the striatum per se may structurally disrupt corticostriatal pathways. The morphology of the striatum may be quantified in vivo using advanced magnetic resonance imaging, as may cognitive functioning pertaining to corticostriatal circuits. It is proposed that striatal morphology may be a biomarker in neurodegenerative disease and potentially the basis of an endophenotype.

Subcortical volumetric reductions in adult Niemann-Pick disease type C: a cross-sectional study.

BACKGROUND AND PURPOSE: Voxel-based analysis has suggested that deep gray matter rather than cortical regions is initially affected in adult Niemann-Pick type C. We sought to examine a range of deep gray matter structures in adults with NPC and relate these to clinical variables. MATERIALS AND METHODS: Ten adult patients with NPC (18-49 years of age) were compared with 27 age- and sex-matched controls, and subcortical structures were automatically segmented from normalized T1-weighted MR images. Absolute volumes (in cubic millimeters) were generated for a range of deep gray matter structures and were compared between groups and correlated with illness variables. RESULTS: Most structures were smaller in patients with NPC compared with controls. The thalamus, hippocampus, and striatum showed the greatest and most significant reductions, and left hippocampal volume correlated with symptom score and cognition. Vertex analysis of the thalamus, hippocampus, and caudate implicated regions involved in memory, executive function, and motor control. CONCLUSIONS: Thalamic and hippocampal reductions may underpin the memory and executive deficits seen in adult NPC. Volume losses in other subcortical regions may also be involved in the characteristic range of motor, psychiatric, and cognitive deficits seen in the disease.

Development of a suspicion index to aid diagnosis of Niemann-Pick disease type C.

OBJECTIVES: Niemann-Pick disease type C (NP-C) is a rare, autosomal recessive lysosomal lipid storage disorder that is invariably fatal. NP-C diagnosis can be delayed for years due to heterogeneous presentation; adult-onset NP-C can be particularly difficult to diagnose. We developed a Suspicion Index tool, ranking specific symptoms within and across domains, including family members who have NP-C, to provide a risk prediction score to identify patients who should undergo testing for NP-C. METHODS: A retrospective chart review was performed in 5 centers in Europe and 2 in Australia (n = 216). Three patient types were selected: classic or variant filipin staining NP-C cases (n = 71), NP-C noncases (confirmed negative by filipin staining; n = 64), or controls with at least 1 characteristic symptom of NP-C (n = 81). NP-C signs and symptoms were categorized into visceral, neurologic, or psychiatric domains. Logistic regression was performed on individual signs and symptoms within and across domains, and regression coefficients were used to develop prediction scores for NP-C. Internal validation was performed with the bootstrap resampling method. RESULTS: The Suspicion Index tool has good discriminatory performance with cutpoints for grading suspicion of NP-C. Neonatal jaundice/cholestasis, splenomegaly, vertical supranuclear gaze palsy, cataplexy, and cognitive decline/dementia were strong predictors of NP-C, as well as symptoms occurring in multiple domains in individual patients, and also parents/siblings or cousins with NP-C. CONCLUSIONS: The Suspicion Index tool is a screening tool that can help identify patients who may warrant further investigation for NP-C. A score ≥70 indicates that patients should be referred for testing for NP-C.

Pontine-to-midbrain ratio indexes ocular-motor function and illness stage in adult Niemann-Pick disease type C.

BACKGROUND AND PURPOSE: Niemann-Pick disease type C (NPC) is a progressive neurovisceral disorder associated with dystonia, ataxia and a characteristic gaze palsy. Neuropathological studies have demonstrated brainstem atrophy associated with neuronal inclusions and loss, and neurofibrillary tangles, although it is not known whether this pathology can be detected in vivo or how these changes relate to illness variables, particularly ocular-motor changes. Our aim was to utilize a method for brainstem atrophy, validated in progressive supranuclear palsy (PSP), in a group of adult patients with NPC, and explore its relationship to illness variables and ocular-motor functioning. METHODS: We calculated the midbrain and pontine area, and pontine-to-midbrain ratio (PMR) from midsagittal images of 10 adult patients with NPC and 27 age- and gender-matched controls. Measures were correlated with illness variables, and measures of horizontal saccadic functioning. RESULTS: Pontine-to-midbrain ratio was 14% higher in the NPC group, but this difference was not significant. However, PMR showed a significant positive correlation with duration of illness and a measure of illness severity. Furthermore, PMR was significantly negatively correlated with saccadic peak velocity and gain, and self-paced saccadic performance. CONCLUSIONS: Pontine-to-midbrain ratio was increased in adult patients with NPC compared to controls, although not to the same degree as previously described in PSP, which also presents with significant gaze palsy. These changes were driven predominantly by progressive midbrain atrophy. The strong correlation with illness and ocular-motor variables suggests that it may be a useful marker for illness progression in NPC.

Size and shape of the corpus callosum in adult Niemann-Pick type C reflects state and trait illness variables.

BACKGROUND AND PURPOSE: Variable alterations to the structure of the corpus callosum have been described in adults with NPC, a neurometabolic disorder known to result in both white and gray matter pathology. This study sought to examine the structure of the callosum in a group of adult patients with NPC and compared callosal structure with a group of matched controls, and to relate callosal structure with state and trait illness variables. MATERIALS AND METHODS: Nine adult patients with NPC were matched to control subjects (n = 26) on age and sex. The corpus callosum was segmented from the midsagittal section of T1-weighted images on all subjects, and total area, length, bending angle, and mean thickness were calculated. In addition, 39 regional thickness measures were derived by using a previously published method. All measures were compared between groups, and analyzed alongside symptom measures, biochemical parameters, and ocular-motor measures. RESULTS: The callosal area and mean thickness were significantly reduced in the patient group, and regional thickness differences were greatest in the genu, posterior body, isthmus, and anterior splenium. Global callosal measures correlated significantly with duration of illness and symptom score, and at trend level with degree of filipin staining. Measures of reflexive saccadic peak velocity and gain, and self-paced saccades, correlated strongly with total callosal area. CONCLUSIONS: Callosal structure and size reflect both state and trait markers in adult NPC, and they may be useful biomarkers to index both white and gray matter changes that reflect illness severity and progression.

Validity and reliability of the Persian language version of the neuropsychiatry unit cognitive assessment tool.

BACKGROUND/AIMS: Only a limited number of cognitive screening tools are available for the Persian-speaking population, and we sought to translate and validate the Neuropsychiatry Unit Cognitive Assessment Tool (NUCOG), a multidimensional cognitive screening tool. METHODS: We used multiple language specialists to translate and then back-translate the NUCOG, and administered the Persian language NUCOG and Mini-Mental State Examination (MMSE) to 184 individuals: 60 controls and 124 patients, 33 of whom had dementia, 30 non-dementing neurological disorders and 61 a psychiatric illness. RESULTS: The NUCOG outperformed the MMSE in differentiating the patient groups and controls. The 'profile' across the 5 NUCOG domains differentiated dementia subgroups such as senile dementia of the Alzheimer type (SDAT), frontotemporal dementia and mild cognitive impairment (MCI). Psychiatric patients with psychosis and posttraumatic stress disorder were more impaired than patients with affective disorders. The NUCOG reliably differentiated controls from patients with MCI (at 86.5/100, sensitivity of 83.3% and specificity of 87.5%) and SDAT (at 75/100, sensitivity and specificity of 100%) patients from controls. CONCLUSIONS: The Persian language NUCOG appears to perform strongly in an unselected population, reliably differentiating patients with dementia from controls, and detecting cognitive impairment in a range of clinical disorders.

White and gray matter alterations in adults with Niemann-Pick disease type C: a cross-sectional study.

OBJECTIVE: Niemann-Pick disease type C (NPC) is a progressive neurovisceral disorder with disrupted intracellular cholesterol metabolism that results in significant alterations to neuronal and axonal structure. Adult patients present with ataxia, gaze palsy, impaired cognition, and neuropsychiatric illness, but the neural substrate has not been well-characterized in vivo. Our aim was to investigate a well-characterized sample of adults with confirmed NPC for gray and white matter abnormalities. METHODS: We utilized a combination of optimized voxel-based morphometry of T1-weighted images and tract-based spatial statistics of diffusion tensor images to examine gray matter volume and white matter structural differences in 6 adult patients with NPC and 18 gender- and age-matched controls. RESULTS: Patients with NPC demonstrated bilateral gray matter reductions in large clusters in bilateral hippocampus, thalamus, superior cerebellum, and insula, in addition to smaller regions of inferoposterior cortex. Patients demonstrated widespread reductions in fractional anisotropy in major white matter tracts. Subsequent analysis of measures of axial and radial diffusivity suggest that these changes are contributed to by both impaired myelination and altered axonal structure. CONCLUSIONS: Findings in gray matter areas are broadly consistent with human and animal studies of selective vulnerability of neuronal populations to the neuropathology of NPC, whereas more widespread white matter changes are consistent with the hypothesis that disrupted myelination and axonal structure predate changes to the neuronal cell body. These findings suggest that volumetric analysis of gray matter and diffusion tensor imaging may be useful modalities for indexing illness stage and monitoring response to emerging treatment.

Preliminary data on the validity and reliability of the Malay version of the NUCOG.

The Neuropsychiatry Unit Cognitive Screening Instrument (NUCOG) provides more detailed screening of cognition than most commonly available tools and was selected for translation into and validation in Bahasa Malaysia (Malay language). It was first translated to Malay, then back-translated to English until changes made were comparable to the original English version. The Malay-translated NUCOG and the Malay version of the Mini-Mental State Examination (MMSE) were delivered to Malay-speaking subjects (n=24). The Malay NUCOG version was then validated by correlating scores against the Malay version of the MMSE and the data tested for reliability of the tool. The Malay version of the NUCOG proved to be a valid (r=0.98, p<0.001) and internally consistent (Cronbach's α=0.76) tool to assess cognitive function and this multi-dimensional cognitive screening instrument is likely to be valuable in the cognitive assessment of neuropsychiatric patients in Malay.

Miglustat in patients with Niemann-Pick disease Type C (NP-C): a multicenter observational retrospective cohort study.

Miglustat has been shown to stabilize disease progression in children, juveniles and adults with Niemann-Pick disease type C (NP-C), a rare genetic disorder characterized by progressive neurological deterioration. We report findings from a retrospective observational cohort study assessing the effects of miglustat on neurological disease progression in patients treated in the clinical practice setting. Data from all NP-C patients prescribed miglustat at 25 expert centers were evaluated using a disease disability scale. The scale analyzed four key parameters of neurological disease progression in NP-C (ambulation, manipulation, language, swallowing). Mean individual parameter scores and a composite score were calculated at baseline (time of diagnosis) and up to 4 follow-up visits. Overall, 66 patients were included (mean [SD] age at diagnosis, 9.7 [7.6] years, and at treatment start, 12.8 [9.5] years). The median (range) miglustat exposure was 1.46 (0.05-4.51) years. Mean annual progression was +0.11 score units/year from diagnosis to treatment start, indicating disease progression prior to therapy, and decreasing to -0.01 score units/year from treatment start to last clinic visit, indicating stabilization. Stabilization of neurological disease on miglustat was observed in all age groups, but the magnitude of the effect was greater in patients diagnosed in late childhood and in juveniles and adults. Stabilization of neurological disease was also observed in a subset of 19 patients with extended pre-treatment information. Overall, these data support previous clinical trial findings indicating clinically relevant beneficial effects of miglustat on neurological disease progression in patients with NP-C.

Gender dimorphism in siblings with schizophrenia-like psychosis due to Niemann-Pick disease type C.

We describe the differential presentation of schizophrenia-like psychosis in two siblings with the 'variant' biochemical presentation of adult Niemann-Pick disease type C. The male sibling presented with psychosis at age 16 years and cognitive and motor disturbance at age 25 years, whereas his elder sister, sharing the same mutation but showing less severe biochemical, neuroimaging and ocular motor parameters, presented with a similar schizophrenia-like illness with associated cognitive and motor disturbance at age 31 years. Their illness onset, course and response to treatment mirrors the sex dimorphism seen in schizophrenia, and is suggestive of an interaction between the neurobiology of their metabolic disorder and sex differences in neurodevelopment.

Frontotemporal dementia presenting as schizophrenia-like psychosis in young people: clinicopathological series and review of cases.

BACKGROUND: Few studies have investigated the relationship between schizophrenia and frontotemporal dementia. AIMS: To investigate this relationship through a clinicopathological investigation of young-onset frontotemporal dementia and a review of the case literature. METHOD: Cases of young-onset frontotemporal dementia were identified within the local brain bank. The clinical course and pathological findings were collated. For the literature review, cases of frontotemporal dementia identified through Medline were selected according to defined criteria. The demographic, clinical, pathological and genetic characteristics of cases presenting with a psychotic illness were identified. RESULTS: In the case series, 5 of 17 patients with frontotemporal dementia had presented with a psychotic illness (schizophrenia/schizoaffective disorder n=4, bipolar disorder n=1) an average of 5 years prior to the dementia diagnosis. Patients with schizophrenia exhibited changes consistent with TDP-43 and ubiquitin-positive frontotemporal dementia. In the cases review, a third of patients aged 30 years or under and a quarter of those aged 40 years or under had been diagnosed with psychosis at presentation. CONCLUSIONS: Patients with young-onset frontotemporal dementia may be diagnosed with a psychotic illness years before the dementia diagnosis is made. These findings have implications for clinicians and for our further understanding of the neurobiology of psychotic illness.

Saccades in adult Niemann-Pick disease type C reflect frontal, brainstem, and biochemical deficits.

BACKGROUND: The autosomal recessive disorder Niemannn-Pick type C (NPC) presents in adulthood with psychosis or cognitive deficits associated with supranuclear gaze palsies. While saccadic innervation to the extraocular muscles is generated in the brainstem, the frontal lobes play an integral role in the initiation of volitional saccades and the suppression of unwanted reflexive saccades. No study has examined the frontally driven volitional control of saccadic eye movements in NPC. OBJECTIVE: To examine self-paced and antisaccades as well as reflexive saccades in adult patients with NPC, a disorder known to affect brainstem and frontal cortical function. METHODS: Three biochemically confirmed adult patients with NPC were compared with 10 matched controls on horizontal saccadic and antisaccadic measures using an infrared limbus eye tracker. Patients' cholesterol esterification and filipin staining, Mini-Mental State performance, and NPC symptom level were rated. RESULTS: Reflexive saccade latency ranged from shorter to longer than normal, reflexive saccade gain was reduced, asymptotic peak velocity was reduced, fewer self-paced saccades were generated, and increased errors on antisaccades were made by patients compared to controls. Patients with more severe biochemical, cognitive, and symptom deficits performed most poorly on brainstem and frontal ocular motor measures. Paradoxically, less severe illness was associated with an abnormally reduced saccadic latency. CONCLUSIONS: Ocular motor measures provide an index of disease severity in Niemannn-Pick type C (NPC) and may be a useful adjunct for monitoring the illness progress and medication response. Reduced saccadic latency may result from inadequate fixation input from abnormally functioning frontal eye fields in NPC.