Visual hallucinations in dementia with Lewy bodies: a transcranial magnetic stimulation study

BACKGROUND: The aetiology of visual hallucinations is poorly understood in dementia with Lewy bodies. Pathological alterations in visual cortical excitability may be one contributory mechanism. AIMS: To determine visual cortical excitability in people with dementia with Lewy bodies compared with aged-matched controls and also the relationship between visual cortical excitability and visual hallucinations in dementia with Lewy bodies. METHOD: Visual cortical excitability was determined by using transcranial magnetic stimulation (TMS) applied to the occiput to elicit phosphenes (transient subjective visual responses) in 21 patients with dementia with Lewy bodies and 19 age-matched controls. RESULTS: Phosphene parameters were similar between both groups. However, in the patients with dementia with Lewy bodies, TMS measures of visual cortical excitability correlated strongly with the severity of visual hallucinations (P = 0.005). Six patients with dementia with Lewy bodies experienced visual hallucination-like phosphenes (for example, seeing people or figures on stimulation) compared with none of the controls (P = 0.02). CONCLUSIONS: Increased visual cortical excitability in dementia with Lewy bodies does not appear to explain visual hallucinations but it may be a marker for their severity.

Longitudinal testing of visual perception in dementia with Lewy bodies and Alzheimer's disease

Visuo-perceptual abnormalities are a prominent feature in dementia with Lewy bodies (DLB) and also occur in Alzheimer's disease (AD) to a lesser extent. We studied the progression of visuo-perceptual abnormalities over a 12-month period in DLB and AD by using a novel computerised test battery.

Testing visual perception in dementia with Lewy bodies and Alzheimer disease

OBJECTIVE Visuoperceptual deficits are common in dementia with Lewy bodies (DLB) and Alzheimer disease (AD). Testing visuoperception in dementia is complicated by decline in other cognitive domains and extrapyramidal features. To overcome these issues, we developed a computerized test, the Newcastle visuoperception battery (NEVIP), which is independent of motor function and has minimal cognitive load.We aimed to test its utility to identify visuoperceptual deficits in people with dementia. PARTICIPANTS AND MEASUREMENTS We recruited 28 AD and 26 DLB participants with 35 comparison participants of similar age and education. The NEVIP was used to test angle, color, and form discrimination along with motion perception to obtain a composite visuoperception score. RESULTS Those with DLB performed significantly worse than AD participants on the composite visuoperception score (Mann-Whitney U = 142, p = 0.01). Visuoperceptual deficits (defined as 2 SD below the performance of comparisons) were present in 71% of the DLB group and 40% of the AD group. Performance was not significantly correlated with motor impairment, but was significantly related to global cognitive impairment in DLB (rs = -0.689, p <0.001), but not in AD. CONCLUSION Visuoperceptual deficits can be detected in both DLB and AD participants using the NEVIP, with the DLB group performing significantly worse than AD. Visuoperception scores obtained by the NEVIP are independent of participant motor deficits and participants are able to comprehend and perform the tasks.

Cholinesterase inhibitors in advanced dementia with Lewy bodies: increase or stop?

INTRODUCTION There is little data on stopping cholinesterase inhibitors in Dementia with Lewy bodies (DLB). Equally, it is not known if increasing the dose of cholinesterase inhibitors may help neuropsychiatric symptoms in advanced DLB. METHOD We conducted an open label trial with donepezil involving 16 patients with LBD when the dose was reduced and treatment stopped over 4 weeks. Another 7 patients were given a trial of an increased dose of donepezil (15 mg) to resolve rehyphen;emergent neuropsychiatric symptoms. RESULTS The slow discontinuation protocol was well tolerated in advanced DLB. Five of the seven patients given a trial of a higher dose of donepezil were rated as clinically improved after 12 weeks treatment. CONCLUSION Cholinesterase inhibitors can be discontinued slowly in advanced DLB. Increasing the dose of donepezil may be of benefit to some patients with DLB who experience a recurrence in their neuropsychiatric symptoms.

More severe functional impairment in dementia with Lewy bodies than Alzheimer disease is related to extrapyramidal motor dysfunction.

OBJECTIVE The objective of this study was to compare functional impairments in dementia with Lewy bodies (DLB) and Alzheimer disease (AD) and their relationship with motor and neuropsychiatric symptoms. METHODS The authors conducted a cross-sectional study of 84 patients with DLB or AD in a secondary care setting. Patients were diagnosed according to published criteria for DLB and AD. The Bristol Activities of Daily Living Scale (BADLS) was used to assess functional impairments. Participants were also assessed using the Unified Parkinson's Disease Rating Scale (motor section), the Neuropsychiatric Inventory, and the Mini-Mental Status Examination. RESULTS Patients with DLB were more functionally impaired and had more motor and neuropsychiatric difficulties than patients with AD with similar cognitive scores. In both AD and DLB, there were correlations between total BADLS scores and motor and neuropsychiatric deficits. There was more impairment in the mobility and self-care components of the BADLS in DLB than in AD, and in DLB, these were highly correlated with UPDRS score. In AD, orientation and instrumental BADLS components were most affected. CONCLUSION The nature of functional disability differs between AD and DLB with additional impairments in mobility and self-care in DLB being mainly attributable to extrapyramidal motor symptoms. Consideration of these is important in assessment and management. Activities of daily living scales for use in this population should attribute the extent to which functional disabilities are related to cognitive, psychiatric, or motor dysfunction.

Characteristics of visual hallucinations in Parkinson disease dementia and dementia with Lewy bodies

OBJECTIVE Parkinson disease dementia (PDD) and dementia with Lewy bodies (DLB) have overlapping clinical and pathologic features. Recurrent visual hallucinations (RVH) are common in both disorders. The authors have compared details of hallucination characteristics and associated neuropsychiatric features in DLB and PDD. METHODS This is a descriptive, cross-sectional study using the Institute of Psychiatry Visual Hallucinations Interview (IP-VHI) to explore self-reported frequency, duration, and phenomenology of RVH in PDD and DLB. The caregivers' ratings of hallucinations and other neuropsychiatric features were elicited with the Neuropsychiatric Inventory (NPI). RESULTS Fifty-six patients (35 PDD; 21 DLB) with RVH were assessed. Hallucination characteristics were similar in both disorders. Simple hallucinations were rare. Most patients experienced complex hallucinations daily, normally lasting minutes. They commonly saw people or animals and the experiences were usually perceived as unpleasant. NPI anxiety scores were higher in PDD. Neuropsychiatric symptoms coexisting with hallucinations were apathy, sleep disturbance, and anxiety. CONCLUSIONS Patients with mild to moderate dementia can provide detailed information about their hallucinations. Characteristics of RVH were similar in PDD and DLB, and phenomenology suggests the involvement of dorsal and ventral visual pathways in their generation. The coexistence of RVH with anxiety, apathy, and sleep disturbance is likely to impair patients' quality of life and may have treatment implications.

Change in perfusion, hallucinations and fluctuations in consciousness in dementia with Lewy bodies.

Fluctuations in consciousness and visual hallucinations are common neuropsychiatric features of dementia with Lewy bodies and Parkinson's disease dementia. To investigate potential neural correlates, we compared how changes in brain perfusion over a 1-year period were related to changes in the severity of these key clinical features. We recruited 29 subjects with either Parkinson's disease with dementia (15 subjects) or dementia with Lewy bodies (14 subjects). Cerebral perfusion was measured using HMPAO SPECT at baseline, and repeated 1 year later. The presence of hallucinations (Neuropsychiatric Inventory), severity of fluctuations in consciousness (fluctuation assessment scale) and cognitive ability (CAMCOG) were assessed at both time points. After controlling for changes in cognitive ability and effect of cholinesterase medication, we found a significant correlation between an increase in perfusion in midline posterior cingulate and decrease in hallucination severity. There was also a significant correlation between increased fluctuations of consciousness and increased thalamic and decreased inferior occipital perfusion. We have identified important neural correlates of key clinical features in Lewy body dementia and postulate that the associations can be understood through the influence of the cholinergic system on attention.