Identifying parkinsonism in mild cognitive impairment

INTRODUCTION

Clinical parkinsonism is a core diagnostic feature for mild cognitive impairment with Lewy bodies (MCI-LB) but can be challenging to identify. A five-item scale derived from the Unified Parkinson's Disease Rating Scale (UPDRS) has been recommended for the assessment of parkinsonism in dementia. This study aimed to determine whether the five-item scale is effective to identify parkinsonism in MCI.

METHODS

Participants with MCI from two cohorts (n = 146) had a physical examination including the UPDRS and [123I]-FP-CIT SPECT striatal dopaminergic imaging. Participants were classified as having clinical parkinsonism (P+) or no parkinsonism (P-), and with abnormal striatal dopaminergic imaging (D+) or normal imaging (D-). The five-item scale was the sum of UPDRS tremor at rest, bradykinesia, action tremor, facial expression, and rigidity scores. The ability of the scale to differentiate P+D+ and P-D- participants was examined.

RESULTS

The five-item scale had an AUROC of 0.92 in Cohort 1, but the 7/8 cut-off defined for dementia had low sensitivity to identify P+D+ participants (sensitivity 25%, specificity 100%). Optimal sensitivity and specificity was obtained at a 3/4 cut-off (sensitivity 83%, specificity 88%). In Cohort 2, the five-item scale had an AUROC of 0.97, and the 3/4 cut-off derived from Cohort 1 showed sensitivity of 100% and a specificity of 82% to differentiate P+D+ from P-D- participants. The five-item scale was not effective in differentiating D+ from D- participants.

CONCLUSIONS

The five-item scale is effective to identify parkinsonism in MCI, but a lower threshold must be used in MCI compared with dementia.

Clinical symptoms in mild cognitive impairment with Lewy bodies: Frequency, time of onset, and discriminant ability

BACKGROUND AND PURPOSE

Mild cognitive impairment with Lewy bodies (MCI-LB) is associated with a range of cognitive, motor, neuropsychiatric, sleep, autonomic, and visual symptoms. We investigated the cumulative frequency of symptoms in a longitudinal cohort of MCI-LB compared with MCI due to Alzheimer disease (MCI-AD) and analysed the ability of a previously described 10-point symptom scale to differentiate MCI-LB and MCI-AD, in an independent cohort.

METHODS

Participants with probable MCI-LB (n = 70), MCI-AD (n = 51), and controls (n = 34) had a detailed clinical assessment and annual follow-up (mean duration = 1.7 years). The presence of a range of symptoms was ascertained using a modified version of the Lewy Body Disease Association Comprehensive LBD Symptom Checklist at baseline assessment and then annually.

RESULTS

MCI-LB participants experienced a greater mean number of symptoms (24.2, SD = 7.6) compared with MCI-AD (11.3, SD = 7.4) and controls (4.2, SD = 3.1; p < 0.001 for all comparisons). A range of cognitive, parkinsonian, neuropsychiatric, sleep, and autonomic symptoms were significantly more common in MCI-LB than MCI-AD, although when present, the time of onset was similar between the two groups. A previously defined 10-point symptom scale demonstrated very good discrimination between MCI-LB and MCI-AD (area under the receiver operating characteristic curve = 0.91, 95% confidence interval = 0.84-0.98), replicating our previous finding in a new cohort.

CONCLUSIONS

MCI-LB is associated with the frequent presence of a particular profile of symptoms compared to MCI-AD. Clinicians should look for evidence of these symptoms in MCI and be aware of the potential for treatment. The presence of these symptoms may help to discriminate MCI-LB from MCI-AD.

Dementia with Lewy bodies: Impact of co-pathologies and implications for clinical trial design

Dementia with Lewy bodies (DLB) is clinically defined by the presence of visual hallucinations, fluctuations, rapid eye movement (REM) sleep behavioral disorder, and parkinsonism. Neuropathologically, it is characterized by the presence of Lewy pathology. However, neuropathological studies have demonstrated the high prevalence of coexistent Alzheimer's disease, TAR DNA-binding protein 43 (TDP-43), and cerebrovascular pathologic cases. Due to their high prevalence and clinical impact on DLB individuals, clinical trials should account for these co-pathologies in their design and selection and the interpretation of biomarkers values and outcomes. Here we discuss the frequency of the different co-pathologies in DLB and their cross-sectional and longitudinal clinical impact. We then evaluate the utility and possible applications of disease-specific and disease-nonspecific biomarkers and how co-pathologies can impact these biomarkers. We propose a framework for integrating multi-modal biomarker fingerprints and step-wise selection and assessment of DLB individuals for clinical trials, monitoring target engagement, and interpreting outcomes in the setting of co-pathologies.

Altered ceramide metabolism is a feature in the extracellular vesicle-mediated spread of alpha-synuclein in Lewy body disorders

Mutations in glucocerebrosidase (GBA) are the most prevalent genetic risk factor for Lewy body disorders (LBD)-collectively Parkinson's disease, Parkinson's disease dementia and dementia with Lewy bodies. Despite this genetic association, it remains unclear how GBA mutations increase susceptibility to develop LBD. We investigated relationships between LBD-specific glucocerebrosidase deficits, GBA-related pathways, and α-synuclein levels in brain tissue from LBD and controls, with and without GBA mutations. We show that LBD is characterised by altered sphingolipid metabolism with prominent elevation of ceramide species, regardless of GBA mutations. Since extracellular vesicles (EV) could be involved in LBD pathogenesis by spreading disease-linked lipids and proteins, we investigated EV derived from post-mortem cerebrospinal fluid (CSF) and brain tissue from GBA mutation carriers and non-carriers. EV purified from LBD CSF and frontal cortex were heavily loaded with ceramides and neurodegeneration-linked proteins including alpha-synuclein and tau. Our in vitro studies demonstrate that LBD EV constitute a "pathological package" capable of inducing aggregation of wild-type alpha-synuclein, mediated through a combination of alpha-synuclein-ceramide interaction and the presence of pathological forms of alpha-synuclein. Together, our findings indicate that abnormalities in ceramide metabolism are a feature of LBD, constituting a promising source of biomarkers, and that GBA mutations likely accelerate the pathological process occurring in sporadic LBD through endolysosomal deficiency.

Prospective predictors of decline v. stability in mild cognitive impairment with Lewy bodies or Alzheimer's disease

BACKGROUND

Mild cognitive impairment (MCI) may gradually worsen to dementia, but often remains stable for extended periods of time. Little is known about the predictors of decline to help explain this variation. We aimed to explore whether this heterogeneous course of MCI may be predicted by the presence of Lewy body (LB) symptoms in a prospectively-recruited longitudinal cohort of MCI with Lewy bodies (MCI-LB) and Alzheimer's disease (MCI-AD).

METHODS

A prospective cohort (n = 76) aged ⩾60 years underwent detailed assessment after recent MCI diagnosis, and were followed up annually with repeated neuropsychological testing and clinical review of cognitive status and LB symptoms. Latent class mixture modelling identified data-driven sub-groups with distinct trajectories of global cognitive function.

RESULTS

Three distinct trajectories were identified in the full cohort: slow/stable progression (46%), intermediate progressive decline (41%) and a small group with a much faster decline (13%). The presence of LB symptomology, and visual hallucinations in particular, predicted decline v. a stable cognitive trajectory. With time zeroed on study end (death, dementia or withdrawal) where available (n = 39), the same subgroups were identified. Adjustment for baseline functioning obscured the presence of any latent classes, suggesting that baseline function is an important parameter in prospective decline.

CONCLUSIONS

These results highlight some potential signals for impending decline in MCI; poorer baseline function and the presence of probable LB symptoms - particularly visual hallucinations. Identifying people with a rapid decline is important but our findings are preliminary given the modest cohort size.

Progression of Clinical Features in Lewy Body Dementia Can Be Detected Over 6 Months

OBJECTIVE

This study aimed to quantify the trajectory and magnitude of change of the key clinical features and corresponding symptom domains of dementia with Lewy bodies (DLB) and Parkinson disease dementia (PDD), including global cognition, parkinsonism, recurrent visual hallucinations, cognitive fluctuations, and sleep disturbance.

METHODS

One hundred sixteen patients with Lewy body dementia (DLB = 72, PDD = 44) underwent assessment at baseline and 3 and 6 months as part of a prospective multicenter randomized controlled trial. Linear mixed models were constructed for core outcome measures using the Mini-Mental State Examination (MMSE), motor section of the Unified Parkinson's Disease Rating Scale (UPDRS-III), Dementia Cognitive Fluctuations Scale (DCFS), and Neuropsychiatric Inventory (NPI).

RESULTS

Within the time frame of our study (6 months), we were able to identify a significant cognitive decline of 1.3 points on the MMSE (p = 0.002) and significant worsening of motor parkinsonism with an increase in UPDRS-III score of 3.2 points (p = 0.018). Fluctuation severity also increased using the DCFS with a 6-month change in score of 1.3 points (p = 0.001). Uniquely, a signal for increased severity of sleep symptoms of 1.2 points (NPI-sleep) was also detectable (p = 0.04). Significant changes in neuropsychiatric symptoms were not detected. There was no difference in rates of change of scores between DLB and PDD.

DISCUSSION

Clinically significant rates of change in core clinical features can be detected and quantified in Lewy body dementia over a relatively short period (6 months) using common clinical instruments and thus may be useful as clinical endpoints for therapeutic trials of disease-modifying and symptomatic agents.

Progression to Dementia in Mild Cognitive Impairment With Lewy Bodies or Alzheimer Disease

OBJECTIVE

To determine whether mild cognitive impairment with Lewy bodies or mild cognitive impairment with Alzheimer disease differ in their rates of clinical progression to dementia, we undertook longitudinal observation of mild cognitive impairment cases with detailed clinical assessment of Lewy body diagnostic characteristics.

METHODS

Two prospective longitudinal cohorts including 111 individuals ≥60 years of age with mild cognitive impairment were assessed annually to track cognitive and clinical progression, including the presence or absence of core clinical features and proposed biomarkers of dementia with Lewy bodies. Multistate modeling was used to assess the associations of diagnostic characteristics of dementia with Lewy bodies with clinical progression from mild cognitive impairment to dementia, with death as a competing outcome.

RESULTS

After a mean follow-up of 2.2 years (range 1-6.7 years), 38 of the 111 (34%) participants progressed to dementia: 10 with AD, 3 with possible dementia with Lewy bodies, and 25 with probable dementia with Lewy bodies. The presence of any Lewy body disease characteristic was associated with an increased hazard of transition to dementia; this risk further increased as more diagnostic characteristics were observed (hazard ratio 1.33 per characteristic, 95% confidence interval [CI] 1.11-1.60) and was especially high for those experiencing complex visual hallucinations (hazard ratio 1.98, 95% CI 0.92-4.29) or cognitive fluctuations (hazard ratio 3.99, 95% CI 2.03-7.84).

CONCLUSIONS

Diagnostic characteristics of Lewy body disease are associated with an increased risk of transition from mild cognitive impairment to dementia.

Cognitive Decline in Mild Cognitive Impairment With Lewy Bodies or Alzheimer Disease: A Prospective Cohort Study

OBJECTIVE

We explored whether the mild cognitive impairment (MCI) stages of dementia with Lewy bodies (DLB) and Alzheimer disease (AD) differ in their cognitive profiles, and longitudinal progression.

DESIGN

A prospective, longitudinal design was utilized with annual follow-up (Max 5 years, Mean 1.9, standard deviation 1.1) after diagnosis. Participants underwent repeated cognitive testing, and review of their clinical diagnosis and symptoms, including evaluation of core features of DLB.

SETTING

This was an observational study of independently living individuals, recruited from local healthcare trusts in North East England, UK.

PARTICIPANTS

An MCI cohort (n = 76) aged ≥60 years was utilized, differentially diagnosed with MCI due to AD (MCI-AD), or possible/probable MCI with Lewy bodies (MCI-LB).

MEASUREMENTS

A comprehensive clinical and neuropsychological testing battery was administered, including ACE-R, trailmaking tests, FAS verbal fluency, and computerized battery of attention and perception tasks.

RESULTS

Probable MCI-LB presented with less impaired recognition memory than MCI-AD, greater initial impairments in verbal fluency and perception of line orientation, and thereafter demonstrated an expedited decline in visuo-constructional functions in the ACE-R compared to MCI-AD. No clear diagnostic group differences were found in deterioration speeds for global cognition, language, overall memory, attention or other executive functions.

CONCLUSION

These findings provide further evidence for differences in severity and decline of visuospatial dysfunctions in DLB compared with AD; further exploration is required to clarify when and how differences in attention, executive, and memory functions emerge, as well as speed of decline to dementia.

Genome sequencing analysis identifies new loci associated with Lewy body dementia and provides insights into its genetic architecture

The genetic basis of Lewy body dementia (LBD) is not well understood. Here, we performed whole-genome sequencing in large cohorts of LBD cases and neurologically healthy controls to study the genetic architecture of this understudied form of dementia, and to generate a resource for the scientific community. Genome-wide association analysis identified five independent risk loci, whereas genome-wide gene-aggregation tests implicated mutations in the gene GBA. Genetic risk scores demonstrate that LBD shares risk profiles and pathways with Alzheimer's disease and Parkinson's disease, providing a deeper molecular understanding of the complex genetic architecture of this age-related neurodegenerative condition.

Neuropathological consensus criteria for the evaluation of Lewy pathology in post-mortem brains: a multi-centre study

Currently, the neuropathological diagnosis of Lewy body disease (LBD) may be stated according to several staging systems, which include the Braak Lewy body stages (Braak), the consensus criteria by McKeith and colleagues (McKeith), the modified McKeith system by Leverenz and colleagues (Leverenz), and the Unified Staging System by Beach and colleagues (Beach). All of these systems use semi-quantitative scoring (4- or 5-tier scales) of Lewy pathology (LP; i.e., Lewy bodies and Lewy neurites) in defined cortical and subcortical areas. While these systems are widely used, some suffer from low inter-rater reliability and/or an inability to unequivocally classify all cases with LP. To address these limitations, we devised a new system, the LP consensus criteria (LPC), which is based on the McKeith system, but applies a dichotomous approach for the scoring of LP (i.e., “absent” vs. “present”) and includes amygdala-predominant and olfactory-only stages. α-Synuclein-stained slides from brainstem, limbic system, neocortex, and olfactory bulb from a total of 34 cases with LP provided by the Newcastle Brain Tissue Resource (NBTR) and the University of Pennsylvania brain bank (UPBB) were scanned and assessed by 16 raters, who provided diagnostic categories for each case according to Braak, McKeith, Leverenz, Beach, and LPC systems. In addition, using LP scores available from neuropathological reports of LP cases from UPBB (n = 202) and NBTR (n = 134), JT (UPBB) and JA (NBTR) assigned categories according to all staging systems to these cases. McKeith, Leverenz, and LPC systems reached good (Krippendorff’s α ≈ 0.6), while both Braak and Beach systems had lower (Krippendorff’s α ≈ 0.4) inter-rater reliability, respectively. Using the LPC system, all cases could be unequivocally classified by the majority of raters, which was also seen for 97.1% when the Beach system was used. However, a considerable proportion of cases could not be classified when using Leverenz (11.8%), McKeith (26.5%), or Braak (29.4%) systems. The category of neocortical LP according to the LPC system was associated with a 5.9 OR (p < 0.0001) of dementia in the 134 NBTR cases and a 3.14 OR (p = 0.0001) in the 202 UPBB cases. We established that the LPC system has good reproducibility and allows classification of all cases into distinct categories. We expect that it will be reliable and useful in routine diagnostic practice and, therefore, suggest that it should be the standard future approach for the basic post-mortem evaluation of LP.

Cholinergic muscarinic M1/M4 receptor networks in dementia with Lewy bodies

Cholinergic dysfunction is central in dementia with Lewy bodies, possibly contributing to the cognitive and psychiatric phenotypes of this condition. We investigated baseline muscarinic M₁/M₄ receptor spatial covariance patterns in dementia with Lewy bodies and their association with changes in cognition and neuropsychiatric symptoms after 12 weeks of treatment with the cholinesterase inhibitor donepezil. Thirty-eight participants (14 cholinesterase inhibitor naive patients, 24 healthy older individuals) underwent ¹²³I-iodo-quinuclidinyl-benzilate (M₁/M₄ receptor assessment) and ^99mTc-exametazime (perfusion) single-photon emission computed tomography scanning. We implemented voxel principal components analysis, producing a series of images representing patterns of inter-correlated voxels across individuals. Linear regression analyses derived specific M₁/M₄ and perfusion spatial covariance patterns associated with patients. A discreet M₁/M₄ pattern that distinguished patients from controls (W_1,19.7 = 16.7, P = 0.001), showed relative decreased binding in right lateral temporal and insula, as well as relative preserved/increased binding in frontal, precuneus, lingual and cuneal regions, implicating nodes within attention and dorsal visual networks. We then derived from patients an M₁/M₄ pattern that correlated with a positive change in mini-mental state examination (r = 0.52, P = 0.05), showing relative preserved/increased uptake in prefrontal, temporal pole and anterior cingulate, elements of attention-related networks. We also generated from patients an M₁/M₄ pattern that correlated with a positive change in neuropsychiatric inventory score (r = 0.77, P = 0.002), revealing relative preserved/increased uptake within a bilateral temporal-precuneal-striatal system. Although in a small sample and therefore tentative, we posit that optimal response of donepezil on cognitive and neuropsychiatric signs in patients with dementia with Lewy bodies were associated with a maintenance of muscarinic M₁/M₄ receptor expression within attentional/executive and ventral visual network hubs, respectively.

Clinical diagnosis of Lewy body dementia

BACKGROUND

Lewy body dementia, consisting of both dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD), is considerably under-recognised clinically compared with its frequency in autopsy series.

AIMS

This study investigated the clinical diagnostic pathways of patients with Lewy body dementia to assess if difficulties in diagnosis may be contributing to these differences.

METHOD

We reviewed the medical notes of 74 people with DLB and 72 with non-DLB dementia matched for age, gender and cognitive performance, together with 38 people with PDD and 35 with Parkinson's disease, matched for age and gender, from two geographically distinct UK regions.

RESULTS

The cases of individuals with DLB took longer to reach a final diagnosis (1.2 v. 0.6 years, P = 0.017), underwent more scans (1.7 v. 1.2, P = 0.002) and had more alternative prior diagnoses (0.8 v. 0.4, P = 0.002), than the cases of those with non-DLB dementia. Individuals diagnosed in one region of the UK had significantly more core features (2.1 v. 1.5, P = 0.007) than those in the other region, and were less likely to have dopamine transporter imaging (P < 0.001). For patients with PDD, more than 1.4 years prior to receiving a dementia diagnosis: 46% (12 of 26) had documented impaired activities of daily living because of cognitive impairment, 57% (16 of 28) had cognitive impairment in multiple domains, with 38% (6 of 16) having both, and 39% (9 of 23) already receiving anti-dementia drugs.

CONCLUSIONS

Our results show the pathway to diagnosis of DLB is longer and more complex than for non-DLB dementia. There were also marked differences between regions in the thresholds clinicians adopt for diagnosing DLB and also in the use of dopamine transporter imaging. For PDD, a diagnosis of dementia was delayed well beyond symptom onset and even treatment.

Research criteria for the diagnosis of prodromal dementia with Lewy bodies

The prodromal phase of dementia with Lewy bodies (DLB) includes (1) mild cognitive impairment (MCI), (2) delirium-onset, and (3) psychiatric-onset presentations. The purpose of our review is to determine whether there is sufficient information yet available to justify development of diagnostic criteria for each of these. Our goal is to achieve evidence-based recommendations for the recognition of DLB at a predementia, symptomatic stage. We propose operationalized diagnostic criteria for probable and possible mild cognitive impairment with Lewy bodies, which are intended for use in research settings pending validation for use in clinical practice. They are compatible with current criteria for other prodromal neurodegenerative disorders including Alzheimer and Parkinson disease. Although there is still insufficient evidence to propose formal criteria for delirium-onset and psychiatric-onset presentations of DLB, we feel that it is important to characterize them, raising the index of diagnostic suspicion and prioritizing them for further investigation.

New evidence on the management of Lewy body dementia

Dementia with Lewy bodies and Parkinson's disease dementia, jointly known as Lewy body dementia, are common neurodegenerative conditions. Patients with Lewy body dementia present with a wide range of cognitive, neuropsychiatric, sleep, motor, and autonomic symptoms. Presentation varies between patients and can vary over time within an individual. Treatments can address one symptom but worsen another, which makes disease management difficult. Symptoms are often managed in isolation and by different specialists, which makes high-quality care difficult to accomplish. Clinical trials and meta-analyses now provide an evidence base for the treatment of cognitive, neuropsychiatric, and motor symptoms in patients with Lewy body dementia. Furthermore, consensus opinion from experts supports the application of treatments for related conditions, such as Parkinson's disease, for the management of common symptoms (eg, autonomic dysfunction) in patients with Lewy body dementia. However, evidence gaps remain and future clinical trials need to focus on the treatment of symptoms specific to patients with Lewy body dementia.

Lewy Body Dementia Association's Research Centers of Excellence Program: Inaugural Meeting Proceedings

The first Lewy Body Dementia Association (LBDA) Research Centers of Excellence (RCOE) Investigator’s meeting was held on December 14, 2017, in New Orleans. The program was established to increase patient access to clinical experts on Lewy body dementia (LBD), which includes dementia with Lewy bodies (DLB) and Parkinson’s disease dementia (PDD), and to create a clinical trials-ready network. Four working groups (WG) were created to pursue the LBDA RCOE aims: (1) increase access to high-quality clinical care, (2) increase access to support for people living with LBD and their caregivers, (3) increase knowledge of LBD among medical and allied (or other) professionals, and (4) create infrastructure for a clinical trials-ready network as well as resources to advance the study of new therapeutics.

Extravascular fibrinogen in the white matter of Alzheimer's disease and normal aged brains: implications for fibrinogen as a biomarker for Alzheimer's disease

The blood-brain barrier (BBB) regulates cerebrovascular permeability and leakage of blood-derived fibrinogen. Dysfunction of the BBB has been associated with cerebral arteriolosclerosis small vessel disease (SVD) and white matter lesions (WML). Furthermore, BBB dysfunction is associated with the pathogenesis of Alzheimer's disease (AD) with the presence of CSF plasma proteins suggested to be a potential biomarker of AD. We aimed to determine if extravascular fibrinogen in the white matter was associated with the development of AD hallmark pathologies, i.e., hyperphosphorylated tau (HPτ) and amyloid-β (Aβ), as well as SVD, cerebral amyloid angiopathy (CAA) and measures of white matter damage. Using human post-mortem brains, parietal tissue from 20 AD and 22 non-demented controls was quantitatively assessed for HPτ, Aβ, white matter damage severity, axonal density, demyelination and the burden of extravascular fibrinogen in both WML and normal appearing white matter (NAWM). SVD severity was determined by calculating sclerotic indices. WML- and NAWM fibrinogen burden was not significantly different between AD and controls nor was it associated with the burden of HPτ or Aβ pathology, or any measures of white matter damage. Increasing severity of SVD was associated with and a predictor of both higher WML- and NAWM fibrinogen burden (all P < 0.05) in controls only. In cases with minimal SVD NAWM fibrinogen burden was significantly higher in the AD cases (P < 0.05). BBB dysfunction was present in both non-demented and AD brains and was not associated with the burden of AD-associated cortical pathologies. BBB dysfunction was strongly associated with SVD but only in the non-demented controls. In cases with minimal SVD, BBB dysfunction was significantly worse in AD cases possibly indicating the influence of CAA. In conclusion, extravascular fibrinogen is not associated with AD hallmark pathologies but indicates SVD, suggesting that the presence of fibrinogen in the CSF is not a surrogate marker for AD pathology.

Consecutive sessions of transcranial direct current stimulation do not remediate visual hallucinations in Lewy body dementia: a randomised controlled trial

BACKGROUND

Complex visual hallucinations are common in Lewy body dementia (LBD) and can cause significant patient and caregiver distress. Current treatments are primarily pharmacological in nature and have limited efficacy and associated side effects. The objective of this study was to assess the effects of consecutive sessions of transcranial direct current stimulation (tDCS) on visual hallucination frequency and severity in LBD, at short-term and long-term follow-up stages.

METHODS

The study was a randomised, double-blind, placebo-controlled trial involving 40 participants with LBD (Mage = 75.52 years, SDage = 8.69 years) which was conducted at a single site between November 2013 and December 2017. Participants received two consecutive 20-min sessions of active (0.048 mA/cm2) or placebo tDCS, separated by a 30-min break, over 5 consecutive days. The anodal electrode was applied to the right parietal cortex (P4) and the cathodal electrode was applied to the occipital cortex (Oz). The primary outcome measure was the Neuropsychiatric Inventory (NPI) hallucinations subscale, as completed by a caregiver/informant at baseline and day 5 (short-term) follow-up, and month 1 and month 3 (long-term) follow-up. Secondary outcome measures included visual cortical excitability, as measured using transcranial magnetic stimulation, computerised attentional and visuoperceptual tasks, and measures of global cognition and cognitive fluctuations.

RESULTS

Complete study data were obtained from 36 participants. There was an overall improvement in visual hallucinations (NPI) for both groups at day 5 relative to baseline, with a medium-to-large effect size; however, compared to placebo, active tDCS did not result in any improvements in visual hallucinations (NPI) at day 5 relative to baseline, or at month 1 or month 3 follow-up time points. Additionally, comparisons of secondary outcome measures showed that active tDCS did not result in any improvements on any measure (visual cortical excitability, attentional and visuoperceptual tasks or cognitive measures) at any time point.

CONCLUSIONS

Repeated consecutive sessions of parietal anodal tDCS, and occipital cathodal tDCS, do not improve visual hallucinations or visuoperceptual function, or alter visual cortical excitability in LBD.

TRIAL REGISTRATION

ISRCTN, ISRCTN40214749 . Registered on 25 October 2013.

Neuropsychiatric symptoms and cognitive profile in mild cognitive impairment with Lewy bodies

BACKGROUND

The accurate clinical characterisation of mild cognitive impairment (MCI) is becoming increasingly important. The aim of this study was to compare the neuropsychiatric symptoms and cognitive profile of MCI with Lewy bodies (MCI-LB) with Alzheimer's disease MCI (MCI-AD).

METHODS

Participants were ⩾60 years old with MCI. Each had a thorough clinical and neuropsychological assessment and 2β-carbomethoxy-3β-(4-iodophenyl)-N-(3-fluoropropyl)-nortropane single photon emission computed tomography FP-CIT SPECT). MCI-LB was diagnosed if two or more diagnostic features of dementia with Lewy bodies were present (visual hallucinations, cognitive fluctuations, motor parkinsonism, rapid eye movement sleep behaviour disorder or positive FP-CIT SPECT). A Lewy body Neuropsychiatric Supportive Symptom Count (LBNSSC) was calculated based on the presence or absence of the supportive neuropsychiatric symptoms defined by the 2017 DLB diagnostic criteria: non-visual hallucinations, delusions, anxiety, depression and apathy.

RESULTS

MCI-LB (n = 41) had a higher LBNSSC than MCI-AD (n = 24; 1.8 ± 1.1 v. 0.7 ± 0.9, p = 0.001). 67% of MCI-LB had two or more of those symptoms, compared with 16% of MCI-AD (Likelihood ratio = 4.2, p < 0.001). MCI-LB subjects scored lower on tests of attention, visuospatial function and verbal fluency. However, cognitive test scores alone did not accurately differentiate MCI-LB from MCI-AD.

CONCLUSIONS

MCI-LB is associated with neuropsychiatric symptoms and a cognitive profile similar to established DLB. This supports the concept of identifying MCI-LB based on the presence of core diagnostic features of DLB and abnormal FP-CIT SPECT imaging. The presence of supportive neuropsychiatric clinical features identified in the 2017 DLB diagnostic criteria was helpful in differentiating between MCI-LB and MCI-AD.

The human brainome: network analysis identifies HSPA2 as a novel Alzheimer&rsquo;s disease target

Our hypothesis is that changes in gene and protein expression are crucial to the development of late-onset Alzheimer’s disease. Previously we examined how DNA alleles control downstream expression of RNA transcripts and how those relationships are changed in late-onset Alzheimer’s disease. We have now examined how proteins are incorporated into networks in two separate series and evaluated our outputs in two different cell lines. Our pipeline included the following steps: (i) predicting expression quantitative trait loci; (ii) determining differential expression; (iii) analysing networks of transcript and peptide relationships; and (iv) validating effects in two separate cell lines. We performed all our analysis in two separate brain series to validate effects. Our two series included 345 samples in the first set (177 controls, 168 cases; age range 65–105; 58% female; KRONOSII cohort) and 409 samples in the replicate set (153 controls, 141 cases, 115 mild cognitive impairment; age range 66–107; 63% female; RUSH cohort). Our top target is heat shock protein family A member 2 (HSPA2), which was identified as a key driver in our two datasets. HSPA2 was validated in two cell lines, with overexpression driving further elevation of amyloid-β40 and amyloid-β42 levels in APP mutant cells, as well as significant elevation of microtubule associated protein tau and phosphorylated-tau in a modified neuroglioma line. This work further demonstrates that studying changes in gene and protein expression is crucial to understanding late onset disease and further nominates HSPA2 as a specific key regulator of late-onset Alzheimer’s disease processes.10.1093/brain/awy215_video1awy215media15824729224001.

Molecular changes in the absence of severe pathology in the pulvinar in dementia with Lewy bodies

BACKGROUND

Dementia with Lewy bodies is characterized by transient clinical features, including fluctuating cognition and visual hallucinations, implicating dysfunction of cerebral hub regions, such as the pulvinar nuclei of the thalamus. However, the pulvinar is typically only mildly affected by Lewy body pathology in dementia with Lewy bodies, suggesting additional factors may account for its proposed dysfunction.

METHODS

We conducted a comprehensive analysis of postmortem pulvinar tissue using whole-transcriptome RNA sequencing, protein expression analysis, and histological evaluation.

RESULTS

We identified 321 transcripts as significantly different between dementia with Lewy bodies cases and neurologically normal controls, with gene ontology pathway analysis suggesting the enrichment of transcripts related to synapses and positive regulation of immune functioning. At the protein level, proteins related to synaptic efficiency were decreased, and general synaptic markers remained intact. Analysis of glial subpopulations revealed astrogliosis without activated microglia, which was associated with synaptic changes but not neurodegenerative pathology.

DISCUSSION

These results indicate that the pulvinar, a region with relatively low Lewy body pathological burden, manifests changes at the molecular level that differ from previous reports in a more severely affected region. We speculate that these alterations result from neurodegenerative changes in regions connected to the pulvinar and likely contribute to a variety of cognitive changes resulting from decreased cortical synchrony in dementia with Lewy bodies. © 2018 International Parkinson and Movement Disorder Society.

Clinical prevalence of Lewy body dementia

Background

The prevalence of dementia with Lewy bodies (DLB) and dementia in Parkinson’s disease (PDD) in routine clinical practice is unclear. Prevalence rates observed in clinical and population-based cohorts and neuropathological studies vary greatly. Small sample sizes and methodological factors in these studies limit generalisability to clinical practice.

Methods

We investigated prevalence in a case series across nine secondary care services over an 18-month period, to determine how commonly DLB and PDD cases are diagnosed and reviewed within two regions of the UK.

Results

Patients with DLB comprised 4.6% (95% CI 4.0–5.2%) of all dementia cases. DLB was represented in a significantly higher proportion of dementia cases in services in the North East (5.6%) than those in East Anglia (3.3%; χ² = 13.6, p < 0.01). DLB prevalence in individual services ranged from 2.4 to 5.9%. PDD comprised 9.7% (95% CI 8.3–11.1%) of Parkinson’s disease cases. No significant variation in PDD prevalence was observed between regions or between services.

Conclusions

We found that the frequency of clinical diagnosis of DLB varied between geographical regions in the UK, and that the prevalence of both DLB and PDD was much lower than would be expected in this case series, suggesting considerable under-diagnosis of both disorders. The significant variation in DLB diagnostic rates between these two regions may reflect true differences in disease prevalence, but more likely differences in diagnostic practice. The systematic introduction of more standardised diagnostic practice could improve the rates of diagnosis of both conditions.

Driving, dementia and the Driver and Vehicle Licensing Agency: a survey of old age psychiatrists

Aims and Method

We surveyed old age psychiatrists in the north-east of England to determine what they considered relevant indicators of driving ability. The survey asked about their satisfaction with the current Driver and Vehicle Licensing Agency (DVLA) procedure of assessing competence to drive in patients with dementia and how they thought this could be improved.

Results

Fifty-seven out of 76 psychiatrists (75%) responded; 26 (45%) respondents thought the forms issued by the DVLA were unsatisfactory but 32 (57%) were satisfied with the eventual decisions made about individual patients. Factors thought to be relevant indicators of driving ability were occupational therapy (n=46, 81%), neuropsychological assessments (n=43, 75%) and carer's report of driving (n=48, 84%). Factors thought not to be relevant were patient's report of driving ability (n=13, 23%) and the Mini Mental State Examination (n=21, 38%).

Clinical Implications

The current system for determining driving ability in people with cognitive impairment and dementia was felt to be unsatisfactory. A multidisciplinary approach and use of on-road driving assessments may improve decision-making.

Symptoms associated with Lewy body disease in mild cognitive impairment

OBJECTIVE

Dementia with Lewy bodies (DLB) is associated with a range of cognitive and non-cognitive symptoms. We aimed to identify if some of these symptoms might aid early diagnosis of Lewy body disease in cases of mild cognitive impairment (MCI).

METHODS

Lewy body MCI (MCI-LB; n = 36), Alzheimer's disease MCI (MCI-AD; n = 21), DLB (n = 36), AD (n = 21) and control (n = 20) participants were recruited. An interview-based questionnaire about the presence of symptoms thought to be associated with Lewy body disease was completed by participants with, where possible, their carer/relative. The prevalence of each symptom was compared between MCI-LB and MCI-AD and between established DLB and AD, and a symptom scale based on these findings was devised.

RESULTS

Fluctuating concentration/attention; episodes of confusion; muscle rigidity; changes in hand-writing, gait and posture; falls; drooling; weak voice; symptoms of REM sleep behaviour disorder (RBD) and misjudging objects were more common in MCI-LB compared with MCI-AD, and also in DLB compared with AD. Hyposmia, tremor, slowness and autonomic symptoms were not specific to Lewy body disease. REM sleep behaviour disorder and hyposmia were reported to develop several years prior to the onset of cognitive symptoms in Lewy body disease. A 10-point symptom scale differentiated between MCI-LB and MCI-AD with a sensitivity of 83% and a specificity of 100%.

CONCLUSIONS

Drooling, misjudging objects and symptoms related to parkinsonism, fluctuating cognition and RBD may be the most characteristic symptoms of MCI-LB. Slowness, tremor, autonomic symptoms and hyposmia are all common in MCI-LB but are not specific to the disease. Copyright © 2017 John Wiley & Sons, Ltd.

Parietal white matter lesions in Alzheimer's disease are associated with cortical neurodegenerative pathology, but not with small vessel disease

Cerebral white matter lesions (WML) encompass axonal loss and demyelination, and the pathogenesis is assumed to be small vessel disease (SVD)-related ischemia. However, WML may also result from the activation of Wallerian degeneration as a consequence of cortical Alzheimer's disease (AD) pathology, i.e. hyperphosphorylated tau (HPτ) and amyloid-beta (Aβ) deposition. WML seen in AD have a posterior predominance compared to non-demented individuals but it is unclear whether the pathological and molecular signatures of WML differ between these two groups. We investigated differences in the composition and aetiology of parietal WML from AD and non-demented controls. Parietal WML tissue from 55 human post-mortem brains (AD, n = 27; non-demented controls, n = 28) were quantitatively assessed for axonal loss and demyelination, as well as for cortical HPτ and Aβ burden and SVD. Biochemical assessment included Wallerian degeneration protease calpain and the myelin-associated glycoprotein (MAG) to proteolipid protein (PLP) ratio (MAG:PLP) as a measure of hypoperfusion. WML severity was associated with both axonal loss and demyelination in AD, but only with demyelination in controls. Calpain was significantly increased in WML tissue in AD, whereas MAG:PLP was significantly reduced in controls. Calpain levels were associated with increasing amounts of cortical AD-pathology but not SVD. We conclude that parietal WML seen in AD differ in their pathological composition and aetiology compared to WML seen in aged controls: WML seen in AD may be associated with Wallerian degeneration that is triggered by cortical AD-pathology, whereas WML in aged controls are due to ischaemia. Hence, parietal WML as seen on MRI should not invariably be interpreted as a surrogate biomarker for SVD as they may be indicative of cortical AD-pathology, and therefore, AD should also be considered as the main underlying cause for cognitive impairment in cases with parietal WML.

Diagnosis and management of dementia with Lewy bodies: Fourth consensus report of the DLB Consortium

The Dementia with Lewy Bodies (DLB) Consortium has refined its recommendations about the clinical and pathologic diagnosis of DLB, updating the previous report, which has been in widespread use for the last decade. The revised DLB consensus criteria now distinguish clearly between clinical features and diagnostic biomarkers, and give guidance about optimal methods to establish and interpret these. Substantial new information has been incorporated about previously reported aspects of DLB, with increased diagnostic weighting given to REM sleep behavior disorder and ¹²³iodine-metaiodobenzylguanidine (MIBG) myocardial scintigraphy. The diagnostic role of other neuroimaging, electrophysiologic, and laboratory investigations is also described. Minor modifications to pathologic methods and criteria are recommended to take account of Alzheimer disease neuropathologic change, to add previously omitted Lewy-related pathology categories, and to include assessments for substantia nigra neuronal loss. Recommendations about clinical management are largely based upon expert opinion since randomized controlled trials in DLB are few. Substantial progress has been made since the previous report in the detection and recognition of DLB as a common and important clinical disorder. During that period it has been incorporated into DSM-5, as major neurocognitive disorder with Lewy bodies. There remains a pressing need to understand the underlying neurobiology and pathophysiology of DLB, to develop and deliver clinical trials with both symptomatic and disease-modifying agents, and to help patients and carers worldwide to inform themselves about the disease, its prognosis, best available treatments, ongoing research, and how to get adequate support.

Neuronal Loss and Α-Synuclein Pathology in the Superior Colliculus and Its Relationship to Visual Hallucinations in Dementia with Lewy Bodies

OBJECTIVE

Patients with dementia with Lewy bodies (DLB) often experience visual hallucinations, which are related to decreased quality of life for patients and increased caregiver distress. The pathologic changes that contribute to visual hallucinations are not known, but several hypotheses implicate deficient attentional processing. The superior colliculus has a role in visual attention and planning eye movements and has been directly implicated in several models of visual hallucinations. Therefore, the present study sought to identify neurodegenerative changes that may contribute to hallucinations in DLB.

METHODS

Postmortem superior colliculus tissue from 13 comparison, 10 DLB, and 10 Alzheimer disease (AD) cases was evaluated using quantitative neuropathologic methods.

RESULTS

α-Synuclein and tau deposition were more severe in deeper layers of the superior colliculus. DLB cases had neuronal density reductions in the stratum griseum intermedium, an important structure in directing attention toward visual targets. In contrast, neuronal density was reduced in all laminae of the superior colliculus in AD.

CONCLUSION

These findings suggest that regions involved in directing attention toward visual targets are subject to neurodegenerative changes in DLB. Considering several hypotheses of visual hallucinations implicating dysfunctional attention toward external stimuli, these findings may provide evidence of pathologic changes that contribute to the manifestation of visual hallucinations in DLB.

Quantitative neuropathology: an update on automated methodologies and implications for large scale cohorts

A tissue microarray (TMA) has previously been developed for use in assessment of neurodegenerative diseases. We investigated the variation of pathology loads in semi-quantitative score categories and how pathology load related to disease progression. Post-mortem tissue from 146 cases were used; Alzheimer's disease (AD) (n = 36), Lewy body disease (LBD) (n = 56), mixed AD/dementia with Lewy bodies (n = 14) and controls (n = 40). TMA blocks (one per case) were constructed using tissue cores from 15 brain regions including cortical and subcortical regions. TMA tissue sections were stained for hyperphosphorylated tau (HP-_T), β amyloid and α-synuclein (αsyn), and quantified using an automated image analysis system. Cases classified as Braak stage VI displayed a wide variation in HP-_T pathology in the entorhinal cortex (interquartile range 4.13-44.03%). The interquartile range for β amyloid in frontal cortex in cases classified as Thal phase 5 was 6.75-17.03% and for αsyn in the cingulate in cases classified as McKeith neocortical LBD was 0.04-0.58%. In AD and control cases, HP-_T load predicted the Braak stage (p < 0.001), β amyloid load predicted Thal phase (p < 0.001) and αsyn load in LBD cases predicted McKeith type of LBD (p < 0.001). Quantitative data from TMA assessment highlight the range in pathological load across cases classified with 'severe' pathology and is beneficial to further elucidate the heterogeneity of neurodegenerative diseases. Quantifying pathology in multiple brain regions may allow identification of novel clinico-pathological phenotypes for the improvement of intra vitam stratification of clinical cohorts according to underlying pathologies.

Specific patterns of neuronal loss in the pulvinar nucleus in dementia with lewy bodies

BACKGROUND

Complex visual hallucinations occur in 70%-80% of dementia with Lewy bodies patients and significantly affect well-being. Despite the prevalence of visual hallucinations in dementia with Lewy bodies, the neuropathological basis of this phenomenon is poorly understood. The pulvinar nucleus of the thalamus has not previously been neuropathologically examined, but has been linked to visual hallucinations in dementia with Lewy bodies. The objective of this study was to investigate whether neuropathological or morphometric changes occur in the pulvinar nucleus in dementia with Lewy bodies cases that may contribute to visual hallucinations.

METHODS

Postmortem pulvinar tissue was acquired from 8 individuals with dementia with Lewy bodies, 8 with Alzheimer's disease, and 8 control cases and was analyzed using stereological and quantitative neuropathological techniques.

RESULTS

Lewy body pathology was present throughout the pulvinar in dementia with Lewy bodies but was most severe in the medial pulvinar. Neuronal loss was found in the lateral pulvinar in dementia with Lewy bodies and Alzheimer's disease but was more severe in dementia with Lewy bodies.

CONCLUSIONS

The pulvinar has an important role in visual attention, visual target selection and affective visual perception. These functions are thought to be deficient in dementia with Lewy bodies and may contribute a vulnerability to visual hallucinations. Therefore, this study has demonstrated neuropathological changes that may promote the manifestation of visual hallucinations in dementia with Lewy bodies. © 2017 International Parkinson and Movement Disorder Society.

TDP-43 pathology in Alzheimer's disease, dementia with Lewy bodies and ageing

Intracellular inclusions consisting of TAR DNA binding protein-43 (TDP-43 pathology) are present in up to 57% of Alzheimer's disease (AD) cases and follow a distinct topographical pattern of progression described in the TDP-43 in AD staging scheme. This scheme has not been applied to the assessment of TDP-43 pathology in dementia with Lewy bodies (DLB) and aged controls. We investigated TDP-43 pathology prevalence and severity in AD, DLB, mixed AD/DLB (Mx AD/DLB) and aged controls. One hundred and nineteen human post-mortem brains were included, neuropathologically diagnosed as AD: 46, DLB: 15, Mx AD/DLB: 19 and aged controls: 39. Paraffin sections inclusive of the amygdala, hippocampus, striatum and neocortex were immunohistochemically stained with antibodies against phosphorylated TDP-43 and staged according to the TDP-43 in AD staging scheme. TDP-43 pathology was present in all groups: AD: 73.9%, DLB: 33.3%, Mx AD/DLB: 52.6% and controls: 17.9%. Prevalence of TDP-43 pathology was significantly higher in AD and Mx AD/DLB compared to controls. In controls, higher age at death was associated with prevalence of TDP-43 pathology and higher TDP-43 in AD stage, suggesting that this type of TDP-43 pathology may partly be an age-associated phenomenon. Significantly higher prevalence of TDP-43 pathology in the AD group indicates that AD pathology possibly triggers and aggravates TDP-43 pathology. The validity of the TDP-43 in AD staging scheme is not limited to AD and should be applied to assess TDP-43 pathology in post mortem brains of aged individuals to further elucidate the role of TDP-43 pathology in age associated neurodegeneration.

Arguing against the proposed definition changes of PD

As members of the Lewy Body Dementia Association Scientific Advisory Council, we aim to address some of the issues raised in the article titled “Time to Redefine PD? Introductory Statement of the MDS Task Force on the Definition of Parkinson's Disease.” In particular, we suggest that the 1‐year rule distinguishing Parkinson's disease dementia from dementia with Lewy bodies is worth maintaining because it serves an important purpose in clinical practice and clinical and basic science research and when helping the lay community understand the complexity of these different clinical phenotypes. Furthermore, we believe that adding an additional diagnostic label, “PD (dementia with Lewy bodies subtype),” will confuse rather than clarify the distinction between dementia with Lewy bodies and PD or PD dementia, and will not improve management or expedite therapeutic development. We present arguments supporting our contentions. © 2016 The Authors. Movement Disorders published by Wiley Periodicals, Inc. on behalf of International Parkinson and Movement Disorder Society.

Depressive symptoms are associated with daytime sleepiness and subjective sleep quality in dementia with Lewy bodies

OBJECTIVE

Sleep problems and depression are common symptoms in dementia with Lewy bodies (DLB), where patients typically experience subjectively poor sleep quality, fatigue and excessive daytime sleepiness. However, whilst sleep disturbances have been linked to depression, this relationship has not received much attention in DLB. The present cross-sectional study addresses this by examining whether depressive symptoms are specifically associated with subjective sleep quality and daytime sleepiness in DLB, and by examining other contributory factors.

METHODS

DLB patients (n = 32) completed the Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS) and the 15-item Geriatric Depression Scale (GDS-15). Motor and cognitive functioning was also assessed. Pearson correlations were used to assess the relationship between GDS-15, ESS and PSQI scores.

RESULTS

GDS-15 scores were positively associated with both ESS (r = 0.51, p < 0.01) and PSQI (r = 0.59, p < 0.001) scores.

CONCLUSIONS

Subjective poor sleep and daytime sleepiness were associated with depressive symptoms in DLB. Given the cross-sectional nature of the present study, the directionality of this relationship cannot be determined, although this association did not appear to be mediated by sleep quality or daytime sleepiness. Nevertheless, these findings have clinical relevance; daytime sleepiness or poor sleep quality might indicate depression in DLB, and subsequent work should examine whether the treatment of depression can reduce excessive daytime sleepiness and improve sleep quality in DLB patients. Alternatively, more rigorous screening for sleep problems in DLB might assist the treatment of depression. © 2015 The Authors. International Journal of Geriatric Psychiatry published by John Wiley & Sons, Ltd.

Analysis of primary visual cortex in dementia with Lewy bodies indicates GABAergic involvement associated with recurrent complex visual hallucinations

Dementia with Lewy bodies (DLB) patients frequently experience well formed recurrent complex visual hallucinations (RCVH). This is associated with reduced blood flow or hypometabolism on imaging of the primary visual cortex. To understand these associations in DLB we used pathological and biochemical analysis of the primary visual cortex to identify changes that could underpin RCVH. Alpha-synuclein or neurofibrillary tangle pathology in primary visual cortex was essentially absent. Neurone density or volume within the primary visual cortex in DLB was also unchanged using unbiased stereology. Microarray analysis, however, demonstrated changes in neuropeptide gene expression and other markers, indicating altered GABAergic neuronal function. Calcium binding protein and GAD65/67 immunohistochemistry showed preserved interneurone populations indicating possible interneurone dysfunction. This was demonstrated by loss of post synaptic GABA receptor markers including gephyrin, GABARAP, and Kif5A, indicating reduced GABAergic synaptic activity. Glutamatergic neuronal signalling was also altered with vesicular glutamate transporter protein and PSD-95 expression being reduced. Changes to the primary visual cortex in DLB indicate that reduced GABAergic transmission may contribute to RCVH in DLB and treatment using targeted GABAergic modulation or similar approaches using glutamatergic modification may be beneficial.

Cholinergic and perfusion brain networks in Parkinson disease dementia

Objective:

To investigate muscarinic M1/M4 cholinergic networks in Parkinson disease dementia (PDD) and their association with changes in Mini-Mental State Examination (MMSE) after 12 weeks of treatment with donepezil.

Methods:

Forty-nine participants (25 PDD and 24 elderly controls) underwent ¹²³I-QNB and ^99mTc-exametazime SPECT scanning. We implemented voxel principal components (PC) analysis, producing a series of PC images of patterns of interrelated voxels across individuals. Linear regression analyses derived specific M1/M4 and perfusion spatial covariance patterns (SCPs).

Results:

We found an M1/M4 SCP of relative decreased binding in basal forebrain, temporal, striatum, insula, and anterior cingulate (F_1,47 = 31.9, p < 0.001) in cholinesterase inhibitor–naive patients with PDD, implicating limbic-paralimbic and salience cholinergic networks. The corresponding regional cerebral blood flow SCP showed relative decreased uptake in temporoparietal and prefrontal areas (F_1,47 = 177.5, p < 0.001) and nodes of the frontoparietal and default mode networks (DMN). The M1/M4 pattern that correlated with an improvement in MMSE (r = 0.58, p = 0.005) revealed relatively preserved/increased pre/medial/orbitofrontal, parietal, and posterior cingulate areas coinciding with the DMN and frontoparietal networks.

Conclusion:

Dysfunctional limbic-paralimbic and salience cholinergic networks were associated with PDD. Established cholinergic maintenance of the DMN and frontoparietal networks may be prerequisite for cognitive remediation following cholinergic treatment in this condition.

Exome sequencing in dementia with Lewy bodies

Dementia with Lewy bodies (DLB) is the second most common form of degenerative dementia. Siblings of affected individuals are at greater risk of developing DLB, but little is known about the underlying genetic basis of the disease. We set out to determine whether mutations in known highly penetrant neurodegenerative disease genes are found in patients with DLB. Whole-exome sequencing was performed on 91 neuropathologically confirmed cases of DLB, supplemented by independent APOE genotyping. Genetic variants were classified using established criteria, and additional neuropathological examination was performed for putative mutation carriers. Likely pathogenic variants previously described as causing monogenic forms of neurodegenerative disease were found in 4.4% of patients with DLB. The APOE ɛ4 allele increased the risk of disease (P=0.0001), conferred a shorter disease duration (P=0.043) and earlier age of death (P=0.0015). In conclusion, although known pathogenic mutations in neurodegenerative disease genes are uncommon in DLB, known genetic risk factors are present in >60% of cases. APOE ɛ4 not only modifies disease risk, but also modulates the rate of disease progression. The reduced penetrance of reported pathogenic alleles explains the lack of a family history in most patients, and the presence of variants previously described as causing frontotemporal dementia suggests a mechanistic overlap between DLB and other neurodegenerative diseases.

Resting state in Parkinson's disease dementia and dementia with Lewy bodies: commonalities and differences

OBJECTIVE

Dementia with Lewy bodies (DLB) and Parkinson's disease dementia (PDD) are two dementias with overlapping phenotypes. Clinically, these are differentiated by the one-year precedence rule between the onset of dementia with respect to Parkinsonism. In this report we aimed to find differences between DLB and PDD in functional connectivity (FC) using resting state functional magnetic resonance imaging, which we hypothesised would reflect the underlying pathological differences between DLB and PDD.

METHODS

The study cohort comprised of 18 patients with DLB, 12 with PDD and 17 healthy control (HC) groups. Eight cortical and four subcortical seeds were chosen, and time series extracted to estimate correlation maps. We also implemented a voxel-based morphometry (VBM) analysis to assess regional grey matter differences. FC analysis was corrected for age, sex and regional grey matter differences.

RESULTS

The FC analysis showed greater alterations in DLB than in PDD for seeds placed within the fronto-parietal network (FPN), whilst in contrast, for the supplementary motor area seed FC alterations were more apparent in PDD than in DLB. However, when comparing DLB and PDD, no significant differences were found. In addition, VBM analysis revealed greater atrophy in PDD than HC and DLB in the bilateral motor cortices and precuneus respectively.

CONCLUSIONS

PDD and DLB demonstrate similar FC alterations in the brain. However, attention- and motor-related seeds revealed subtle differences between both conditions when compared with HC, which may relate to the neuropathology and chronological precedence of core symptoms in the Lewy body dementias.

Regional covariance of muscarinic acetylcholine receptors in Alzheimer's disease using (R, R) [(123)I]-QNB SPECT

Alzheimer's disease (AD) is characterised by deficits in cholinergic neurotransmission and subsequent receptor changes. We investigated (123)I-iodo-quinuclidinyl-benzilate (QNB) SPECT images using spatial covariance analysis (SCA), to detect an M1/M4 receptor spatial covariance pattern (SCP) that distinguished AD from controls. Furthermore, a corresponding regional cerebral blood flow (rCBF) SCP was also derived. Thirty-nine subjects (15 AD and 24 healthy elderly controls) underwent (123)I-QNB and (99m)Tc-exametazime SPECT. Voxel SCA was simultaneously applied to the set of smoothed/registered scans, generating a series of eigenimages representing common intercorrelated voxels across subjects. Linear regression identified individual M1/M4 and rCBF SCPs that discriminated AD from controls. The M1/M4 SCP showed concomitant decreased uptake in medial temporal, inferior frontal, basal forebrain and cingulate relative to concomitant increased uptake in frontal poles, occipital, pre-post central and precuneus/superior parietal regions (F1,37 = 85.7, p < 0.001). A largely different perfusion SCP was obtained showing concomitant decreased rCBF in medial and superior temporal, precuneus, inferior parietal and cingulate relative to concomitant increased rCBF in cerebellum, pre-post central, putamen, fusiform and brain stem/midbrain regions (F1,37 = 77.5, p < 0.001). The M1/M4 SCP expression correlated with the duration of cognitive symptoms (r = 0.90, p < 0.001), whereas the rCBF SCP expression negatively correlated with MMSE, CAMCOG and CAMCOGmemory (r ≥ |0.63|, p ≤ 0.006). (123)I-QNB SPECT revealed an M1/M4 basocortical covariance pattern, distinct from rCBF, reflecting the duration of disease rather than current clinical symptoms. This approach could be more sensitive than univariate methods in characterising the cholinergic/rCBF changes that underpin the clinical phenotype of AD.