Deep learning assisted quantitative analysis of Aß and microglia in patients with idiopathic normal pressure hydrocephalus in relation to cognitive outcome.

Neuropathologic changes of Alzheimer disease (AD) including Aß accumulation and neuroinflammation are frequently observed in the cerebral cortex of patients with idiopathic normal pressure hydrocephalus (iNPH). We created an automated analysis platform to quantify Aß load and reactive microglia in the vicinity of Aß plaques and to evaluate their association with cognitive outcome in cortical biopsies of patients with iNPH obtained at the time of shunting. Aiforia Create deep learning software was used on whole slide images of Iba1/4G8 double immunostained frontal cortical biopsies of 120 shunted iNPH patients to identify Iba1-positive microglia somas and Aß areas, respectively. Dementia, AD clinical syndrome (ACS), and Clinical Dementia Rating Global score (CDR-GS) were evaluated retrospectively after a median follow-up of 4.4 years. Deep learning artificial intelligence yielded excellent (>95%) precision for tissue, Aß, and microglia somas. Using an age-adjusted model, higher Aß coverage predicted the development of dementia, the diagnosis of ACS, and more severe memory impairment by CDR-GS whereas measured microglial densities and Aß-related microglia did not correlate with cognitive outcome in these patients. Therefore, cognitive outcome seems to be hampered by higher Aß coverage in cortical biopsies in shunted iNPH patients but is not correlated with densities of surrounding microglia.

Early Alzheimer's disease pathology in human cortex involves transient cell states.

Cellular perturbations underlying Alzheimer's disease (AD) are primarily studied in human postmortem samples and model organisms. Here, we generated a single-nucleus atlas from a rare cohort of cortical biopsies from living individuals with varying degrees of AD pathology. We next performed a systematic cross-disease and cross-species integrative analysis to identify a set of cell states that are specific to early AD pathology. These changes-which we refer to as the early cortical amyloid response-were prominent in neurons, wherein we identified a transitional hyperactive state preceding the loss of excitatory neurons, which we confirmed by acute slice physiology on independent biopsy specimens. Microglia overexpressing neuroinflammatory-related processes also expanded as AD pathology increased. Finally, both oligodendrocytes and pyramidal neurons upregulated genes associated with ß-amyloid production and processing during this early hyperactive phase. Our integrative analysis provides an organizing framework for targeting circuit dysfunction, neuroinflammation, and amyloid production early in AD pathogenesis.

Cerebrospinal Fluid Diagnostics of Alzheimer's Disease in Patients with Idiopathic Normal Pressure Hydrocephalus.

BACKGROUND: Alzheimer's disease (AD) is the most common cause of dementia worldwide and a frequent comorbidity in idiopathic normal pressure hydrocephalus (iNPH). The presence of AD pathology is associated with worse outcomes after a shunt procedure in iNPH. Preoperative diagnosis of AD is challenging in patients with iNPH, which involves reduced concentrations of the cerebrospinal fluid (CSF) AD biomarkers. OBJECTIVE: Our aim was to estimate the effect size of iNPH as a factor in CSF levels of AD biomarkers and to test if correction could be used to improve diagnostic value. METHODS: Our cohort included 222 iNPH patients with data in the Kuopio NPH registry and brain biopsy and CSF samples available. We divided the patients into groups according to AD pathology per brain biopsy. For control cohorts, we had CSF samples from cognitively healthy individuals (n = 33) and patients with diagnosed AD and no iNPH (n = 39).*-31ptResults:Levels of all investigated biomarkers differed significantly between groups, with the exception of t-Tau levels between healthy individuals and iNPH patients with AD pathology. Applying a correction factor for each biomarker (0.842*Aß1 - 42, 0.779*t-Tau, and 0.610*P-Tau181) for the effect of iNPH yielded a sensitivity of 2.4% and specificity of 100%. The ratio of P-Tau181 to Aß1 - 42 was moderately effective in aiding recognition of AD pathology in iNPH patients (sensitivity 0.79, specificity 0.76, area under the curve 0.824). CONCLUSION: Correcting for iNPH as a factor failed to improve diagnostic effectiveness, but the P-Tau181/Aß1 - 42 ratio showed some utility in the diagnosis of AD in iNPH patients.

Upper limb dysfunction and activities in daily living in idiopathic normal pressure hydrocephalus.

BACKGROUND: Idiopathic normal pressure hydrocephalus (iNPH) is a neurodegenerative disease with a characteristic symptom triad of gait disturbance, cognitive decline, and incontinence. Recently, also dysfunctions in upper limbs have been described in iNPH and reported to improve after shunt surgery. We aim to describe the role of upper limb motor function in the clinical assessment of iNPH patients and its influence on activities of daily living (ADL). METHODS: Seventy-five consecutive patients with probable iNPH were studied pre-operatively and at 3 and 12 months after shunt surgery. The pre-operative evaluation included lumbar drainage of cerebrospinal fluid (tap test). Motor functions were assessed in upper and lower limbs with Grooved Pegboard Test (GPT), Box & Block Test (BBT), Total Score of Gait (TSG), and balance test. ADL was assessed with Barthel's index and cognition in accordance with the Consortium to Establish a Registry for Alzheimer's Disease (CERAD). RESULTS: Patients showed improvement in all motor tests and ADL at 3 months after shunt surgery. The improvement remained stable during the 12-month post-operative follow-up. The motor function tests correlated with each other and with ADL. CONCLUSIONS: A 3-month follow-up period after shunt surgery is adequate to show improvement in motor tasks, and a positive outcome will last for at least 12 months. A shunt-responsive dysfunction of upper limb motor performance plays a major role in ADL of iNPH patients. Therefore, we suggest an evaluation of upper limb motor performance to be included in routine evaluation of iNPH patients.

Elevated CSF LRG and Decreased Alzheimer's Disease Biomarkers in Idiopathic Normal Pressure Hydrocephalus.

Leucine-rich-alpha-2-glykoprotein (LRG) is suggested as a potential biomarker for idiopathic normal pressure hydrocephalus (iNPH). Our goal was to compare the cerebrospinal fluid (CSF) LRG levels between 119 iNPH patients and 33 age-matched controls and with the shunt responses and the brain biopsy Alzheimer's disease (AD) pathology among the iNPH patients. CSF LRG, Aß1-42, P-tau181, and T-tau were measured by using commercial ELISAs. The LRG levels in the CSF were significantly increased in the iNPH patients (p < 0.001) as compared to the controls, regardless of the AD pathology. However, CSF LRG did not correlate with the shunt response in contrast to the previous findings. The CSF AD biomarkers, i.e., Aß1-42, T-tau, and P-tau correlated with the brain biopsy AD pathology as expected but were systematically lower in the iNPH patients when compared to the controls (<0.001). Our findings support that the LRG levels in the CSF are potentially useful for the diagnostics of iNPH, independent of the brain AD pathology, but contrary to previous findings, not for predicting the shunt response. Our findings also suggest a need for specific reference values of the CSF AD biomarkers for the diagnostics of comorbid AD pathology in the iNPH patients.

Time Trends of Cerebrospinal Fluid Biomarkers of Neurodegeneration in Idiopathic Normal Pressure Hydrocephalus.

BACKGROUND: Longitudinal changes in cerebrospinal fluid (CSF) biomarkers are seldom studied. Furthermore, data on biomarker gradient between lumbar (L-) and ventricular (V-) compartments seems to be discordant. OBJECTIVE: To examine alteration of CSF biomarkers reflecting Alzheimer's disease (AD)-related amyloid-ß (Aß) aggregation, tau pathology, neurodegeneration, and early synaptic degeneration by CSF shunt surgery in idiopathic normal pressure hydrocephalus (iNPH) in relation to AD-related changes in brain biopsy. In addition, biomarker levels in L- and V-CSF were compared. METHODS: L-CSF was collected prior to shunt placement and, together with V-CSF, 3-73 months after surgery. Thereafter, additional CSF sampling took place at 3, 6, and 18 months after the baseline sample from 26 iNPH patients with confirmed Aß plaques in frontal cortical brain biopsy and 13 iNPH patients without Aß pathology. CSF Amyloid-ß42 (Aß42), total tau (T-tau), phosphorylated tau (P-tau181), neurofilament light (NFL), and neurogranin (NRGN) were analyzed with customized ELISAs. RESULTS: All biomarkers but Aß42 increased notably by 140-810% in L-CSF after CSF diversion and then stabilized. Aß42 instead showed divergent longitudinal decrease between Aß-positive and -negative patients in L-CSF, and thereafter increase in Aß-negative iNPH patients in both L- and V-CSF. All five biomarkers correlated highly between V-CSF and L-CSF (Aß42 R = 0.87, T-tau R = 0.83, P-tau R = 0.92, NFL R = 0.94, NRGN R = 0.9; all p < 0.0001) but were systematically lower in V-CSF (Aß42 14 %, T-tau 22%, P-tau 20%, NFL 32%, NRGN 19%). With APOE genotype-grouping, only Aß42 showed higher concentration in non-carriers of allele ɛ4. CONCLUSION: Longitudinal follow up shows that after an initial post-surgery increase, T-tau, P-tau, and NRGN are stable in iNPH patients regardless of brain biopsy Aß pathology, while NFL normalized toward its pre-shunt levels. Aß42 as biomarker seems to be the least affected by the surgical procedure or shunt and may be the best predictor of AD risk in iNPH patients. All biomarker concentrations were lower in V- than L-CSF yet showing strong correlations.

Predicting Development of Alzheimer's Disease in Patients with Shunted Idiopathic Normal Pressure Hydrocephalus.

BACKGROUND: Idiopathic normal pressure hydrocephalus (iNPH) patients often develop Alzheimer's disease (AD) related brain pathology. Disease State Index (DSI) is a method to combine data from various sources for differential diagnosis and progression of neurodegenerative disorders. OBJECTIVE: To apply DSI to predict clinical AD in shunted iNPH-patients in a defined population. METHODS: 335 shunted iNPH-patients (median 74 years) were followed until death (n = 185) or 6/2015 (n = 150). DSI model (including symptom profile, onset age of NPH symptoms, atrophy of medial temporal lobe in CT/MRI, cortical brain biopsy finding, and APOE genotype) was applied. Performance of DSI model was evaluated with receiver operating characteristic (ROC) curve analysis. RESULTS: A total of 70 (21%) patients developed clinical AD during median follow-up of 5.3 years. DSI-model predicted clinical AD with moderate effectiveness (AUC = 0.75). Significant factors were cortical biopsy (0.69), clinical symptoms (0.66), and medial temporal lobe atrophy (0.66). CONCLUSION: We found increased occurrence of clinical AD in previously shunted iNPH patients as compared with general population. DSI supported the prediction of AD. Cortical biopsy during shunt insertion seems indicated for earlier diagnosis of comorbid AD.

[11C]PIB PET Is Associated with the Brain Biopsy Amyloid-ß Load in Subjects Examined for Normal Pressure Hydrocephalus.

BACKGROUND: Idiopathic normal pressure hydrocephalus (iNPH) is frequently associated with concomitant amyloid-ß (Aß) pathology. OBJECTIVE: To compare the [11C]PIB PET uptake in the patients with suspected iNPH to Aß and hyperphosphorylated-tau (HPτ) in the right frontal cortical biopsy, the cerebrospinal fluid (CSF) Aß, the response to a CSF shunt, and the final clinical diagnosis of Alzheimer's disease (AD). METHODS: Patients (n = 21) from Kuopio NPH Registry (http://www.uef.fi/nph) with intraventricular pressure monitoring, immunostaining for Aß and HPτ in the right frontal cortical biopsies, and a Mini-Mental State Examination and a Clinical Dementia Rating underwent [11C]PIB PET. Aß, total tau, and Pτ181 were measured by ELISA from the ventricular (n = 15) and the lumbar (n = 9) CSF. Response to the shunt was seen in 13 out of the 15 shunted patients. AD was diagnosed in 8 patients during a median follow-up of 6 years (mean 7.3±2.4 years, range 3-1). RESULTS: [11C]PIB uptake in the right frontal cortex (ρ= 0.60, p < 0.01) and the combined neocortical [11C]PIB uptake score (ρ= 0.61, p < 0.01) were associated with a higher Aß load in the right frontal cortical biopsy. Excluding one (1/15) outlier, [11C]PIB uptake was also associated with the ventricular CSF Aß (ρ= -0.58, p = 0.03). CONCLUSIONS: The findings show that [11C]PIB PET can reliably detect simultaneous amyloid pathology among the iNPH patients. Further studies will show whether amyloid PET could predict a clinical response to the shunt operation. In addition, the presence of Aß pathology in the patients with iNPH might also warrant treatment with current AD drugs.

Copy number loss in SFMBT1 is common among Finnish and Norwegian patients with iNPH.

OBJECTIVE: To evaluate the role of the copy number loss in SFMBT1 in a Caucasian population. METHODS: Five hundred sixty-seven Finnish and 377 Norwegian patients with idiopathic normal pressure hydrocephalus (iNPH) were genotyped and compared with 508 Finnish elderly, neurologically healthy controls. The copy number loss in intron 2 of SFMBT1 was determined using quantitative PCR. RESULTS: The copy number loss in intron 2 of SFMBT1 was detected in 10% of Finnish (odds ratio [OR] = 1.9, p = 0.0078) and in 21% of Norwegian (OR = 4.7, p < 0.0001) patients with iNPH compared with 5.4% in Finnish controls. No copy number gains in SFMBT1 were detected in patients with iNPH or healthy controls. The carrier status did not provide any prognostic value for the effect of shunt surgery in either population. Moreover, no difference was detected in the prevalence of hypertension or T2DM between SFMBT1 copy number loss carriers and noncarriers. CONCLUSIONS: This is the largest and the first multinational study reporting the increased prevalence of the copy number loss in intron 2 of SFMBT1 among patients with iNPH, providing further evidence of its role in iNPH. The pathogenic role still remains unclear, requiring further study.

Alterations in mitochondria-endoplasmic reticulum connectivity in human brain biopsies from idiopathic normal pressure hydrocephalus patients.

Idiopathic normal pressure hydrocephalus (iNPH) is a neuropathology with unknown cause characterised by gait impairment, cognitive decline and ventriculomegaly. These patients often present comorbidity with Alzheimer's disease (AD), including AD pathological hallmarks such as amyloid plaques mainly consisting of amyloid ß-peptide and neurofibrillary tangles consisting of hyperphosphorylated tau protein. Even though some of the molecular mechanisms behind AD are well described, little is known about iNPH. Several studies have reported that mitochondria-endoplasmic reticulum contact sites (MERCS) regulate amyloid ß-peptide metabolism and conversely that amyloid ß-peptide can influence the number of MERCS. MERCS have also been shown to be dysregulated in several neurological pathologies including AD.In this study we have used transmission electron microscopy and show, for the first time, several mitochondria contact sites including MERCS in human brain biopsies. These unique human brain samples were obtained during neurosurgery from 14 patients that suffer from iNPH. Three of these 14 patients presented comorbidities with other dementias: one patient with AD, one with AD and vascular dementia and one patient with Lewy body dementia. Furthermore, we report that the numbers of MERCS are increased in biopsies obtained from patients diagnosed with dementia. Moreover, the presence of both amyloid plaques and neurofibrillary tangles correlates with decreased contact length between endoplasmic reticulum and mitochondria, while amyloid plaques alone do not seem to affect endoplasmic reticulum-mitochondria apposition. Interestingly, we report a significant positive correlation between the number of MERCS and ventricular cerebrospinal fluid amyloid ß-peptide levels, as well as with increasing age of iNPH patients.

Prevalence of immunological diseases in a Finnish frontotemporal lobar degeneration cohort with the C9orf72 repeat expansion carriers and non-carriers.

Recent studies have suggested a role for immune dysregulation behind the etiology of frontotemporal lobar degeneration (FTLD). Here, we have investigated the prevalence of immunological diseases in FTLD (N = 196) with and without the C9orf72 repeat expansion, Alzheimer's disease (AD) (N = 193) and not cognitively impaired (NCI) subjects (N = 92). The prevalence was 16.3% in FTLD, 13.5% in AD and 15.2% in NCI. Although differences between the groups did not reach statistical significance, the frequency of immunological diseases was the highest in FTLD without the C9orf72 expansion (22/117, 18.8%) and the lowest in FTLD with the expansion (6/56, 10.7%), suggesting that the C9orf72 expansion possibly influences immunological pathways in FTLD.

S-[18F]THK-5117-PET and [11C]PIB-PET Imaging in Idiopathic Normal Pressure Hydrocephalus in Relation to Confirmed Amyloid-ß Plaques and Tau in Brain Biopsies.

BACKGROUND: Detection of pathological tau aggregates could facilitate clinical diagnosis of Alzheimer's disease (AD) and monitor drug effects in clinical trials. S-[18F]THK-5117 could be a potential tracer to detect pathological tau deposits in brain. However, no previous study have correlated S-[18F]THK-5117 uptake in PET with brain biopsy verified tau pathology in vivo. OBJECTIVE: Here we aim to evaluate the association between cerebrospinal fluid (CSF) AD biomarkers, S-[18F]THK-5117, and [11C]PIB PET against tau and amyloid lesions in brain biopsy. METHODS: Fourteen patients with idiopathic normal pressure hydrocephalus (iNPH) with previous shunt surgery including right frontal cortical brain biopsy and CSF Aß1 - 42, total tau, and P-tau181 measures, underwent brain MRI, [11C]PIB PET, and S-[18F]THK-5117 PET imaging. RESULTS: Seven patients had amyloid-ß (Aß, 4G8) plaques, two both Aß and phosphorylated tau (Pτ, AT8) and one only Pτ in biopsy. As expected, increased brain biopsy Aß was well associated with higher [11C]PIB uptake in PET. However, S-[18F]THK-5117 uptake did not show any statistically significant correlation with either brain biopsy Pτ or CSF P-tau181 or total tau. CONCLUSIONS: S-[18F]THK-5117 lacked clear association with neuropathologically verified tau pathology in brain biopsy probably, at least partially, due to off-target binding. Further studies with larger samples of patients with different tau tracers are urgently needed. The detection of simultaneous Aß and tau pathology in iNPH is important since that may indicate poorer and especially shorter response for CSF shunt surgery compared with no pathology.

Incidence, Comorbidities, and Mortality in Idiopathic Normal Pressure Hydrocephalus.

OBJECT: To investigate the incidence, comorbidities, mortality, and causes of death in idiopathic normal pressure hydrocephalus (iNPH). METHODS: A cohort of 536 patients with possible NPH from a defined population with a median follow-up time of 5.1 years, (range 0.04-19.9 years) was included in the study. Patients were evaluated by brain imaging and intraventricular pressure monitoring, with a brain biopsy specimen immunostained against amyloid-ß and hyperphosphorylated τ. Hospital records were reviewed for vascular diseases and type 2 diabetes mellitus (T2DM). Death certificates and yearly population of the catchment area were obtained from national registries. RESULTS: A total of 283 patients had a clinical diagnosis of iNPH, leading to a median annual incidence of 1.58 iNPH patients per 100,000 inhabitants (range, 0.8-4.5). Alzeimer disease-related brain biopsy findings were less frequent in iNPH patients than in non-iNPH patients (P < 0.05). An overrepresentation of hypertension (52% vs. 33%, P < 0.001) and T2DM (23% vs. 13%, P = 0.002) was noted in iNPH patients. Age (hazard ratio [HR] 1.04/year, 95% confidence interval [CI] 1.03-1.06, P < 0.001) and T2DM (HR 1.63, 95% CI 1.23-2.16, P < 0.001) increased the risk of death in the iNPH patients and in the total population. iNPH was associated with decreased risk of death (HR 0.63, 95% CI 0.50-0.78, P < 0.001). The most frequent causes of death were cardiovascular and cerebrovascular disease. Dementia as a cause of death was more common in non-iNPH patients (27% vs. 10%, P < 0.001). CONCLUSIONS: Hypertension and T2DM are common in iNPH and the latter causes excess mortality in the affected patients.

Why Does the Health-Related Quality of Life in Idiopathic Normal-Pressure Hydrocephalus Fail to Improve Despite the Favorable Clinical Outcome?

OBJECTIVE: Occasionally, a favorable clinical disease-specific outcome does not reflect into improved generic health-related quality of life (HRQoL) in patients with idiopathic normal-pressure hydrocephalus (iNPH) at 1 year after the installation of a cerebrospinal fluid shunt. Our aim was to identify factors causing this discrepancy. METHODS: The 1-year HRQoL outcomes of 141 patients with iNPH were evaluated with the generic 15D instrument, in which the minimum clinically important change/difference on the 0-1 scale has been estimated to be ±0.015. A 12-point iNPH grading scale (iNPHGS) was used as a clinical disease-specific outcome measure, in which a 1-point decrease is considered to be clinically important. We identified 29 (21%) patients with iNPH from our prospective study whose HRQoL deteriorated or remained the same despite of a favorable iNPHGS outcome. We analyzed this discrepancy using patients' clinical variables and characteristics. RESULTS: Multivariate binary logistic regression analysis indicated that a greater (worse) iNPHGS score at baseline (adjusted odds ratio [OR], 1.7; 95% confidence interval [CI] 1.3-2.3; P < 0.001), comorbid chronic pulmonary disease (40% vs. 20%; adjusted OR 17.8; 95% CI 3.6-89.9; P < 0.001), and any comorbid nonmetastatic tumor (62% vs. 17%; adjusted OR 11.5; 95% CI 1.5-85.3; P = 0.017) predicted discrepancy between iNPHGS and 15D outcomes. CONCLUSIONS: Frail patients suffering from certain pre-existing comorbidities may not experience improvement in generic HRQoL despite of a favorable clinical disease-specific response. Acknowledging the comorbidity burden of the patient may help clinicians and the patients to understand the conflict between patient-reported and clinical outcomes.

Associations of intracranial pressure with brain biopsy, radiological findings, and shunt surgery outcome in patients with suspected idiopathic normal pressure hydrocephalus.

BACKGROUND: It remains unclear how intracranial pressure (ICP) measures are associated with brain biopsies and radiological markers. Here, we aim to investigate associations between ICP and radiological findings, brain biopsies, and shunt surgery outcome in patients with suspected idiopathic normal pressure hydrocephalus (iNPH). METHOD: In this study, we retrospectively analyzed data from 73 patients admitted with suspected iNPH to Kuopio University Hospital. Of these patients, 71% underwent shunt surgery. The NPH registry included data on clinical and radiological examinations, 24-h intraventricular pressure monitoring, and frontal cortical biopsy. RESULTS: The mean ICP and mean ICP pulse wave amplitude were not associated with the shunt response. Aggregations of Alzheimer's disease (AD)-related proteins (amyloid-ß, hyperphosphorylated tau) in frontal cortical biopsies were associated with a poor shunt response (P = 0.014). High mean ICP was associated with Evans' index (EI; P = 0.025), disproportional sylvian and suprasylvian subarachnoid spaces (P = 0.014), and focally dilated sulci (P = 0.047). Interestingly, a high pulse wave amplitude was associated with AD-related biopsy findings (P = 0.032), but the mean ICP was not associated with the brain biopsy. The ICP was not associated with medial temporal lobe atrophy, temporal horn widths, or white matter changes. ICP B waves were associated with less atrophy of the medial temporal lobe (P = 0.018) and more severe disproportionality between the sylvian and suprasylvian subarachnoid spaces (P = 0.001). CONCLUSIONS: The EI and disproportional sylvian and suprasylvian subarachnoid spaces were associated with mean ICP. Disproportionality was also associated with ICP B waves. These associations, although rather weak, with elevated ICP in 24-h measurements, support their value in iNPH diagnostics and suggest that these radiological markers are potentially related to the pathogenesis of iNPH. Interestingly, our results suggested that elevated pulse wave amplitude might be associated with brain amyloid accumulation.

Multimodal analysis to predict shunt surgery outcome of 284 patients with suspected idiopathic normal pressure hydrocephalus.

OBJECTIVES: Optimal selection of idiopathic normal pressure hydrocephalus (iNPH) patients for shunt surgery is challenging. Disease State Index (DSI) is a statistical method that merges multimodal data to assist clinical decision-making. It has previously been shown to be useful in predicting progression in mild cognitive impairment and differentiating Alzheimer's disease (AD) and frontotemporal dementia. In this study, we use the DSI method to predict shunt surgery response for patients with iNPH. METHODS: In this retrospective cohort study, a total of 284 patients (230 shunt responders and 54 non-responders) from the Kuopio NPH registry were analyzed with the DSI. Analysis included data from patients' memory disorder assessments, age, clinical symptoms, comorbidities, medications, frontal cortical biopsy, CT/MRI imaging (visual scoring of disproportion between Sylvian and suprasylvian subarachnoid spaces, atrophy of medial temporal lobe, superior medial subarachnoid spaces), APOE genotyping, CSF AD biomarkers, and intracranial pressure. RESULTS: Our analysis showed that shunt responders cannot be differentiated from non-responders reliably even with the large dataset available (AUC = 0.58). CONCLUSIONS: Prediction of the treatment response in iNPH is challenging even with our extensive dataset and refined analysis. Further research of biomarkers and indicators predicting shunt responsiveness is still needed.

SEPT8 modulates ß-amyloidogenic processing of APP by affecting the sorting and accumulation of BACE1.

Dysfunction and loss of synapses are early pathogenic events in Alzheimer's disease. A central step in the generation of toxic amyloid-ß (Aß) peptides is the cleavage of amyloid precursor protein (APP) by ß-site APP-cleaving enzyme (BACE1). Here, we have elucidated whether downregulation of septin (SEPT) protein family members, which are implicated in synaptic plasticity and vesicular trafficking, affects APP processing and Aß generation. SEPT8 was found to reduce soluble APPß and Aß levels in neuronal cells through a post-translational mechanism leading to decreased levels of BACE1 protein. In the human temporal cortex, we identified alterations in the expression of specific SEPT8 transcript variants in a manner that correlated with Alzheimer's-disease-related neurofibrillary pathology. These changes were associated with altered ß-secretase activity. We also discovered that the overexpression of a specific Alzheimer's-disease-associated SEPT8 transcript variant increased the levels of BACE1 and Aß peptides in neuronal cells. These changes were related to an increased half-life of BACE1 and the localization of BACE1 in recycling endosomes. These data suggest that SEPT8 modulates ß-amyloidogenic processing of APP through a mechanism affecting the intracellular sorting and accumulation of BACE1.

High Risk of Dementia in Ventricular Enlargement with Normal Pressure Hydrocephalus Related Symptoms1.

BACKGROUND: Differential diagnosis of ventricular enlargement with normal pressure hydrocephalus (NPH) related symptoms is challenging. Patients with enlarged ventricles often manifest cognitive deterioration but their long-term outcome is not well known. OBJECTIVES: We aim to evaluate long-term cognitive outcome in patients with enlarged ventricles and clinically suspected NPH. METHODS: A neurologist and a neurosurgeon clinically evaluated 468 patients with enlarged ventricles and suspected NPH using radiological methods, intraventricular pressure monitoring, and frontal cortical brain biopsy. The neurologist confirmed final diagnoses after a median follow-up interval of 4.8 years. RESULTS: Altogether, 232 patients (50%) with enlarged ventricles did not fulfill the criteria for shunt surgery. The incidence of dementia among patients with enlarged ventricles, and at least one NPH-related symptom with adequate follow-up data (n = 446) was high, varying from 77 (iNPH, shunt responders) to 141/1000 person-years (non-shunted patients with enlarged ventricles). At the end of the follow-up, 59% of all these patients were demented. The demented population comprised 73% of non-shunted patients with enlarged ventricles, 63% of shunted iNPH patients that did not respond to treatment, and 46% of iNPH patients that were initially responsive to shunting. The most common cause of dementia was Alzheimer's disease (n = 94, 36%), followed by vascular dementia (n = 68, 26%). CONCLUSIONS: One-half of patients with enlarged ventricles and clinically suspected NPH were not shunted after intraventricular pressure monitoring. Dementia caused by various neurodegenerative diseases was frequently seen in patients with ventricular enlargement. Thus, careful diagnostic evaluation in collaboration with neurologists and neurosurgeons is emphasized.

Amyloid-ß and Tau Dynamics in Human Brain Interstitial Fluid in Patients with Suspected Normal Pressure Hydrocephalus.

BACKGROUND: Amyloid-ß (Aß1 - 42), total tau (T-tau), and phosphorylated tau (P-tau181) in the cerebrospinal fluid (CSF) are the most promising biomarkers of Alzheimer's disease (AD). Still, little is known about the dynamics of these molecules in the living brain. In a transgenic mouse brain, soluble Aß decreases with increasing age and advanced Aß pathology as seen similarly in CSF. OBJECTIVE: To assess the relationship between AD-related pathological changes in human brain tissue, ventricular and lumbar CSF, and brain interstitial fluid (ISF). METHODS: Altogether 11 patients with suspected idiopathic normal pressure hydrocephalus underwent frontal cortical brain biopsy, 24-h intraventricular pressure monitoring, and a microdialysis procedure. AD-related biomarkers were analyzed from brain tissue, CSF, and ISF. RESULTS: ISF T-tau levels decreased strongly within the first 12 h, then plateauing until the end of the experiment. Aß1 - 42 and P-tau181 remained stable during the experiment (n = 3). T-tau and P-tau were higher in the ISF than in ventricular or lumbar CSF, while Aß1 - 42 levels were within similar range in both CSF and ISF samples. ISF P-tau correlated with the ventricular CSF T-tau (r = 0.70, p = 0.017) and P-tau181 (r = 0.64, p = 0.034). Five patients with amyloid pathology in the brain biopsy tended to reveal lower ISF Aß1 - 42 levels than those six without amyloid pathology. CONCLUSIONS: This is the first study to report ISF Aß and tau levels in the human brain without significant brain injury. The set-up used enables sampling from the brain ISF for at least 24 h without causing adverse effects due to the microdialysis procedure to follow the dynamics of the key molecules in AD pathogenesis in the living brain at various stages of the disease.

Cerebrospinal fluid biomarker and brain biopsy findings in idiopathic normal pressure hydrocephalus.

BACKGROUND: The significance of amyloid precursor protein (APP) and neuroinflammation in idiopathic normal pressure hydrocephalus (iNPH) and Alzheimer's disease (AD) is unknown. OBJECTIVE: To investigate the role of soluble APP (sAPP) and amyloid beta (Aß) isoforms, proinflammatory cytokines, and biomarkers of neuronal damage in the cerebrospinal fluid (CSF) in relation to brain biopsy Aß and hyperphosphorylated tau (HPτ) findings. METHODS: The study population comprised 102 patients with possible NPH with cortical brain biopsies, ventricular and lumbar CSF samples, and DNA available. The final clinical diagnoses were: 53 iNPH (91% shunt-responders), 26 AD (10 mixed iNPH+AD), and 23 others. Biopsy samples were immunostained against Aß and HPτ. CSF levels of AD-related biomarkers (Aß42, p-tau, total tau), non-AD-related Aß isoforms (Aß38, Aß40), sAPP isoforms (sAPPα, sAPPß), proinflammatory cytokines (several interleukins (IL), interferon-gamma, monocyte chemoattractant protein-1, tumor necrosis factor-alpha) and biomarkers of neuronal damage (neurofilament light and myelin basic protein) were measured. All patients were genotyped for APOE. RESULTS: Lumbar CSF levels of sAPPα were lower (p<0.05) in patients with shunt-responsive iNPH compared to non-iNPH patients. sAPPß showed a similar trend (p = 0.06). CSF sAPP isoform levels showed no association to Aß or HPτ in the brain biopsy. Quantified Aß load in the brain biopsy showed a negative correlation with CSF levels of Aß42 in ventricular (r = -0.295, p = 0.003) and lumbar (r = -0.356, p = 0.01) samples, while the levels of Aß38 and Aß40 showed no correlation. CSF levels of proinflammatory cytokines and biomarkers of neuronal damage did not associate to the brain biopsy findings, diagnosis, or shunt response. Higher lumbar/ventricular CSF IL-8 ratios (p<0.001) were seen in lumbar samples collected after ventriculostomy compared to the samples collected before the procedure. CONCLUSIONS: The role of sAPP isoforms in iNPH seems to be independent from the amyloid cascade. No neuroinflammatory background was observed in iNPH or AD.