Metabolic alterations in patients with Parkinson disease and visual hallucinations
ABSTRACT Visual hallucinations (VHs) occur frequently in advanced stages of Parkinson disease (PD). Which brain regions are affected in PD with VH is not well understood.
To characterize the pattern of affected brain regions in PD with VH and to determine whether functional changes in PD with VH occur preferentially in visual association areas, as is suggested by the complex clinical symptomatology.
Positron emission tomography measurements using fluorodeoxyglucose F 18. Between-group statistical analysis, accounting for the variance related to disease stage.
University hospital. Patients Eight patients with PD and VH and 11 patients with PD without VH were analyzed. The presence of VH during the month before positron emission tomography was rated using the Neuropsychiatric Inventory subscale for VH (PD and VH, 4.63; PD without VH, 0.00; P < .002).
Parkinson disease with VH, compared with PD without VH, was characterized by reduction in the regional cerebral metabolic rate for glucose consumption (P < .05, corrected for false discovery rate) in occipitotemporoparietal regions, sparing the occipital pole. No significant increase in regional glucose metabolism was detected in patients with PD and VH.
The pattern of resting-state metabolic changes in regions of the dorsal and ventral visual streams, but not in primary visual cortex, in patients with PD and VH, is compatible with the functional roles of visual association areas in higher-order visual processing. These findings may help to further elucidate the functional mechanisms underlying VH in PD.
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ABSTRACT: Impaired visual processing may play a role in the pathophysiology of visual hallucinations in Parkinson's disease. In order to study involved neuronal circuitry, we assessed cerebral activation patterns both before and during recognition of gradually revealed images in Parkinson's disease patients with visual hallucinations (PDwithVHs), Parkinson's disease patients without visual hallucinations (PDnonVHs) and healthy controls. We hypothesized that, before image recognition, PDwithVHs would show reduced bottom-up visual activation in occipital-temporal areas and increased (pre)frontal activation, reflecting increased top-down demand. Overshoot of the latter has been proposed to play a role in generating visual hallucinations. Nine non-demented PDwithVHs, 14 PDnonVHs and 13 healthy controls were scanned on a 3 Tesla magnetic resonance imaging scanner. Static images of animals and objects gradually appearing out of random visual noise were used in an event-related design paradigm. Analyses were time-locked on the moment of image recognition, indicated by the subjects' button-press. Subjects were asked to press an additional button on a colour-changing fixation dot, to keep attention and motor action constant and to assess reaction times. Data pre-processing and statistical analysis were performed with statistical parametric mapping-5 software. Bilateral activation of the fusiform and lingual gyri was seen during image recognition in all groups (P < 0.001). Several seconds before image recognition, PDwithVHs showed reduced activation of the lateral occipital cortex, compared with both PDnonVHs and healthy controls. In addition, reduced activation of extrastriate temporal visual cortices was seen just before image recognition in PDwithVHs. The association between increased vulnerability for visual hallucinations in Parkinson's disease and impaired visual object processing in occipital and temporal extrastriate visual cortices supported the hypothesis of impaired bottom-up visual processing in PDwithVHs. Support for the hypothesized increased top-down frontal activation was not obtained. The finding of activation reductions in ventral/lateral visual association cortices in PDwithVHs before image recognition further helps to explain functional mechanisms underlying visual hallucinations in Parkinson's disease.Brain 09/2009; 132(Pt 11):2980-93. DOI:10.1093/brain/awp223 · 10.23 Impact Factor
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ABSTRACT: The aim of this work was to determine the progression of cognitive impairment in Parkinson's disease (PD) patients with or without hallucinations. Two years after the first assessment, 36 PD patients were re-evaluated on standardized neuropsychological tests, including the Frontal Assessment Battery (FAB), and on rating scales for overall cognitive functioning, functional autonomy, behavioral disorders. Nine patients had hallucinations at baseline and endpoint assessments; 12 patients developed hallucinations during the follow-up; and 15 patients were hallucination-free throughout the study. Cognitive performance significantly declined in all three groups, but at endpoint assessment PD hallucinators scored significantly lower than nonhallucinators on phonological and semantic fluency tasks, immediate free recall and the go/no-go FAB subtest; moreover, they showed more severe apathy than nonhallucinators. Reduced phonological fluency at baseline (odds ratio [OR], 13.5; 95% CI: 1.34-135.98, P = 0.027) was the only independent predictor of onset of hallucinations after 2 years, whereas hallucinations (OR, 10.1; 95% CI: 1.94-51.54, P = 0.006) and poor phonological fluency (OR, 6.1; 95% CI: 1.04-35.03, P = 0.045) independently predicted development of diffuse cognitive impairment. We concluded that reduced verbal fluency scores may predict the onset of hallucinations, while hallucinations and poor phonological fluency may predict development of dementia in PD patients.Movement Disorders 12/2007; 22(16):2418-25. DOI:10.1002/mds.21746 · 5.63 Impact Factor
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ABSTRACT: To identify the pattern of cerebral hypometabolism in patients with dementia with Lewy bodies (DLB) and visual hallucinations (VH). Fourteen patients with DLB and VH, 7 with DLB without VH and 16 healthy controls underwent clinical and (18)F-FDG PET evaluations. The 2 patient groups did not significantly differ in their clinical characteristics, except in the occurrence of VH. A voxel-wise comparison of (18)F-FDG PET scans was conducted between each of the 2 patient groups and the control group, and the patient groups among each other. Compared with the control group, hypometabolic regions were more extensive and confluent in the patient group with VH than in the group without VH. The direct comparison between the 2 patient groups revealed a significant metabolic deficit in the group with VH at the right occipito-temporal junction and the right middle frontal gyrus. These results suggest that hypometabolism in visual association areas rather than the primary visual cortex is involved in VH in DLB.Dementia and Geriatric Cognitive Disorders 02/2008; 25(6):531-8. DOI:10.1159/000132084 · 2.81 Impact Factor