Hemispheric asymmetries in hippocampal volume related to memory in left and right temporal variants of frontotemporal degeneration.

In addition to Alzheimer's disease (AD), the hippocampus is now known to be affected in variants of frontotemporal degeneration (FTD). In semantic variant primary progressive aphasia (svPPA), characterized by language impairments, hippocampal atrophy is greater in the left hemisphere. Nonverbal impairments (e.g., visual object recognition) are prominent in the right temporal variant of FTD (rtvFTD), and hippocampal atrophy may be greater in the right hemisphere. In this study we examined the hypothesis that leftward hippocampal asymmetry (predicted in svPPA) would be associated with selective verbal memory impairments (with relative preservation of visual memory), while rightward asymmetry (predicted in rtvFTD) would be associated with the opposite pattern (greater visual memory impairment). In contrast, we predicted that controls and individuals in the amnestic mild cognitive impairment stage of AD (aMCI), both of whom were expected to show symmetrical hippocampal volumes, would show roughly equivalent scores in verbal and visual memory. Participants completed delayed recall tests with words and geometric shapes, and hippocampal volumes were assessed with MRI. The aMCI sample showed symmetrical hippocampal atrophy, and similar degree of verbal and visual memory impairment. The svPPA sample showed greater left hippocampal atrophy and verbal memory impairment, while rtvFTD showed greater right hippocampal atrophy and visual memory impairment. Greater asymmetry in hippocampal volumes was associated with larger differences between verbal and visual memory in the FTD samples. Unlike AD, asymmetry is a core feature of brain-memory relationships in temporal variants of FTD.

Multi-shell diffusion MRI of the fornix as a biomarker for cognition in Alzheimer's disease.

BACKGROUND AND PURPOSE: A substantial fraction of those who had Alzheimer's Disease (AD) pathology on autopsy did not have dementia in life. While biomarkers for AD pathology are well-developed, biomarkers specific to cognitive domains affected by early AD are lagging. Diffusion MRI (dMRI) of the fornix is a candidate biomarker for early AD-related cognitive changes but is susceptible to bias due to partial volume averaging (PVA) with cerebrospinal fluid. The purpose of this work is to leverage multi-shell dMRI to correct for PVA and to evaluate PVA-corrected dMRI measures in fornix as a biomarker for cognition in AD. METHODS: Thirty-three participants in the Cleveland Alzheimer's Disease Research Center (CADRC) (19 with normal cognition (NC), 10 with mild cognitive impairment (MCI), 4 with dementia due to AD) were enrolled in this study. Multi-shell dMRI was acquired, and voxelwise fits were performed with two models: 1) diffusion tensor imaging (DTI) that was corrected for PVA and 2) neurite orientation dispersion and density imaging (NODDI). Values of tissue integrity in fornix were correlated with neuropsychological scores taken from the Uniform Data Set (UDS), including the UDS Global Composite 5 score (UDSGC5). RESULTS: Statistically significant correlations were found between the UDSGC5 and PVA-corrected measure of mean diffusivity (MDc, r = -0.35, p < 0.05) from DTI and the intracelluar volume fraction (ficvf, r = 0.37, p < 0.04) from NODDI. A sensitivity analysis showed that the relationship to MDc was driven by episodic memory, which is often affected early in AD, and language. CONCLUSION: This cross-sectional study suggests that multi-shell dMRI of the fornix that has been corrected for PVA is a potential biomarker for early cognitive domain changes in AD. A longitudinal study will be necessary to determine if the imaging measure can predict cognitive decline.

Lewy body pathology modifies risk factors for cerebral amyloid angiopathy when comorbid with Alzheimer's disease pathology.

INTRODUCTION: Cerebral amyloid angiopathy (CAA) often accompanies dementia-associated pathologies and is important in the context of anti-amyloid monoclonal therapies and risk of hemorrhage. METHODS: We conducted a retrospective neuropathology-confirmed study of 2384 participants in the National Alzheimer Coordinating Center cohort (Alzheimer's disease [AD], n = 1175; Lewy body pathology [LBP], n = 316; and mixed AD and LBP [AD-LBP], n = 893). We used logistic regression to evaluate age, sex, education, APOE ε4, neuritic plaques, and neurofibrillary tangles (NFTs) in CAA risk. RESULTS: APOE ε4 increased CAA risk in all three groups, while younger age and higher NFT stages increased risk in AD and AD-LBP. In AD-LBP, male sex and lower education were additional risk factors. The odds of APOE ε4 carrier homozygosity related to CAA was higher in LBP (25.69) and AD-LBP (9.50) than AD (3.17). DISCUSSION: AD and LBPs modify risk factors for CAA and should be considered in reviewing the risk of CAA. HIGHLIGHTS: Lewy body pathology modifies risk factors for cerebral amyloid angiopathy (CAA) when present along with Alzheimer's disease (AD) neuropathology. In the context of anti-amyloid monoclonal therapies and their associated risks for hemorrhage, the risk of underlying CAA in mixed dementia with Lewy body pathology needs to be considered.

ATN cerebrospinal fluid biomarkers in dementia with Lewy bodies: Initial results from the United States Dementia with Lewy Bodies Consortium.

INTRODUCTION: The National Institute on Aging - Alzheimer's Association (NIA-AA) ATN research framework proposes to use biomarkers for amyloid (A), tau (T), and neurodegeneration (N) to stage individuals with AD pathological features and track changes longitudinally. The overall aim was to utilize this framework to characterize pre-mortem ATN status longitudinally in a clinically diagnosed cohort of dementia with Lewy bodies (DLB) and to correlate it with the post mortem diagnosis. METHODS: The cohort was subtyped by cerebrospinal fluid (CSF) ATN category. A subcohort had longitudinal data, and a subgroup was neuropathologically evaluated. RESULTS: We observed a significant difference in Aß42/40 after 12 months in the A+T- group. Post mortem neuropathologic analyses indicated that most of the p-Tau 181 positive (T+) cases also had a high Braak stage. DISCUSSION: This suggests that DLB patients who are A+ but T- may need to be monitored to determine whether they remain A+ or ever progress to T positivity. HIGHLIGHTS: Some A+T- DLB subjects transition from A+ to negative after 12-months. Clinically diagnosed DLB with LBP-AD (A+T+) maintain their positivity. Clinically diagnosed DLB with LBP-AD (A+T+) maintain their positivity. Monitoring of the A+T- sub-type of DLB may be necessary.

The Media Coverage of Bruce Willis Reveals Unfamiliarity With Frontotemporal Degeneration.

In 2022, Bruce Willis' family released a statement saying that he had been diagnosed with aphasia (an acquired language impairment) and would no longer be acting. Ten months later, the Willis family released another statement indicating that he received a more specific diagnosis of frontotemporal degeneration (FTD). This resulted in an explosion of media coverage, as prominent news outlets scrambled to produce stories describing FTD to a public largely unfamiliar with the disease. The quality of these stories varied widely, and in many cases the relationship between aphasia and FTD was misrepresented, as were basic descriptions and facts about FTD. FTD refers to a class of protein-misfolding diseases that are a common cause of aphasias due to neurodegeneration, or primary progressive aphasias (PPA). Rather than describing how FTD was discovered to be the underlying source of Mr. Willis' aphasia, many reports described his aphasia as "progressing into" FTD, implying they are two different disorders. Furthermore, these reports used the terminology of frontotemporal "dementia" rather than "degeneration", a term that invokes many stereotypes in the public imagination and may have contributed to misrepresentations in coverage. Instead of focusing on the language symptoms of PPA, reports often emphasized the personality and behavioral changes more closely associated with other variants of FTD. The substance of various facts, such as how common FTD is and how it can be treated, varied widely across reports. In sum, the media coverage of Mr. Willis' diagnosis reveals the extent to which the media and general public are uninformed about FTD and PPA. The remedy for this problem is to promote greater awareness of FTD, in both the public and the medical provider class. The Willis family's disclosure was a courageous act that helped bring much-needed attention to this disease.

Metabolic syndrome biomarkers relate to rate of cognitive decline in MCI and dementia stages of Alzheimer's disease.

BACKGROUND: The relationship between biomarkers of metabolic syndrome and insulin resistance, plasma triglyceride/HDL cholesterol (TG/HDL-C) ratio, on the rate of cognitive decline in mild cognitive impairment (MCI) and dementia stages of Alzheimer's disease (AD) is unknown. The role of peripheral and cerebrospinal fluid (CSF) levels of Apolipoprotein A1 (ApoA1), a key functional component of HDL, on cognitive decline also remains unclear among them. Here we evaluate baseline plasma TG/HDL-C ratio and CSF and plasma ApoA1 levels and their relation with cognitive decline in the MCI and Dementia stages of AD. PATIENTS AND METHODS: A retrospective longitudinal study (156 participants; 106 MCI, 50 AD dementia) from the Alzheimer's Disease Neuroimaging Initiative, with an average of 4.0 (SD 2.8) years follow-up. Baseline plasma TG/HDL-C, plasma, and CSF ApoA1 and their relationship to inflammation and blood-brain barrier (BBB) biomarkers and longitudinal cognitive outcomes were evaluated. Multivariable linear mixed effect models were used to assess the effect of baseline analytes with longitudinal changes in Mini-Mental State Exam (MMSE), Clinical Dementia Rating-Sum of Boxes (CDR-SB), and Logical Memory delayed recall (LM) score after controlling for well-known covariates. RESULTS: A total of 156 participants included 98 women, 63%; mean age was 74.9 (SD 7.3) years. At baseline, MCI and dementia groups did not differ significantly in TG/HDL-C (Wilcoxon W statistic = 0.39, p = 0.39) and CSF ApoA1 levels (W = 3642, p = 0.29), but the dementia group had higher plasma ApoA1 than the MCI group (W = 4615, p = 0.01). Higher TG/HDL-C ratio was associated with faster decline in CDR-SB among MCI and dementia groups. Higher plasma ApoA1 was associated with faster decline in MMSE and LM among MCI, while in contrast higher CSF ApoA1 levels related to slower cognitive decline in MMSE among MCI. CSF and plasma ApoA1 also show opposite directional correlations with biomarkers of BBB integrity. CSF but not plasma levels of ApoA1 positively correlated to inflammation analytes in the AGE-RAGE signaling pathway in diabetic complications (KEGG ID:KO04933). CONCLUSIONS: Biomarkers of metabolic syndrome relate to rate of cognitive decline among MCI and dementia individuals. Elevated plasma TG/HDL-C ratio and plasma ApoA1 are associated with worse cognitive outcomes in MCI and dementia participants. CSF ApoA1 and plasma ApoA1 likely have different roles in AD progression in MCI stage.

Initial non-amnestic symptoms relate to faster rate of functional and cognitive decline compared to amnestic symptoms in neuropathologically confirmed dementias.

INTRODUCTION: The relationship between initial cognitive symptoms and subsequent rate of clinical decline is important in clinical care and the design of dementia clinical trials. METHODS: This retrospective longitudinal, autopsy-confirmed, cohort study among 2426 participants in the National Alzheimer's Coordinating Center database included Alzheimer's disease (AD) pathology, n = 1187; Lewy body pathology (LBP), n = 331; and mixed pathology (AD-LBP), n = 904. The predominant initial cognitive symptom was assessed clinically. Linear mixed models evaluated the longitudinal outcome of the Clinical Dementia Rating-Sum of Boxes (CDR-SB) score. RESULTS: Non-amnestic initial symptoms had a faster rate of decline than amnestic symptoms in all three groups. Language symptoms had a faster rate of decline in all three groups. Executive symptoms had a faster rate of decline than amnestic in AD and AD-LBP. There was a similar trend for visuospatial symptoms in AD-LBP. DISCUSSION: Initial cognitive symptoms, despite varied underlying pathology, are a predictor of longitudinal functional outcomes among dementias. HIGHLIGHTS: Initial non-amnestic symptoms had a faster rate of longitudinal cognitive and functional decline on the Clinical Dementia Rating-Sum of Boxes (CDR-SB) scores than amnestic symptoms among Alzheimer's disease, Lewy body pathology, and mixed neuropathology. Given the relative size of CDR-SB changes in Alzheimer's disease clinical trials, clarifying the nature of initial symptoms could be an important variable in ensuring appropriately designed clinical trials.

Metabolic labeling unveils alterations in the turnover of HDL-associated proteins during diabetes progression in mice.

Several aspects of diabetes pathophysiology and complications result from hyperglycemia-induced alterations in the structure and function of plasma proteins. Furthermore, insulin has a significant influence on protein metabolism by affecting both the synthesis and degradation of proteins in various tissues. To understand the role of progressive hyperglycemia on plasma proteins, in this study, we measured the turnover rates of high-density lipoprotein (HDL)-associated proteins in control (chow diet), prediabetic [a high-fat diet (HFD) for 8 wk] or diabetic [HFD for 8 wk with low-dose streptozotocin (HFD + STZ) in weeks 5-8 of HFD] C57BL/6J mice using heavy water (2H2O)-based metabolic labeling approach. Compared with control mice, HFD and HFD + STZ mice showed elevations of fasting plasma glucose levels in the prediabetic and diabetic range, respectively. Furthermore, the HFD and HFD + STZ mice showed increased hepatic triglyceride (TG) levels, total plasma cholesterol, and plasma TGs. The kinetics of 40 proteins were quantified using the proteome dynamics method, which revealed an increase in the fractional synthesis rate (FSR) of HDL-associated proteins in the prediabetic mice compared with control mice, and a decrease in FSR in the diabetic mice. The pathway analysis revealed that proteins with altered turnover rates were involved in acute-phase response, lipid metabolism, and coagulation. In conclusion, prediabetes and diabetes have distinct effects on the turnover rates of HDL proteins. These findings suggest that an early dysregulation of the HDL proteome dynamics can provide mechanistic insights into the changes in protein levels in these conditions.NEW & NOTEWORTHY This study is the first to examine the role of gradual hyperglycemia during diabetes disease progression on HDL-associated protein dynamics in the prediabetes and diabetic mice. Our results show that the fractional synthesis rate of HDL-associated proteins increased in the prediabetic mice whereas it decreased in the diabetic mice compared with control mice. These kinetic changes can help to elucidate the mechanism of altered protein levels and HDL dysfunction during diabetes disease progression.

Association of Variation in Behavioral Symptoms With Initial Cognitive Phenotype in Adults With Dementia Confirmed by Neuropathology.

IMPORTANCE: Behavioral and psychological symptoms of dementia (BPSDs) in association with amnestic and nonamnestic cognitive phenotypes have not been evaluated across diagnoses of Alzheimer disease pathology (ADP), Lewy body-related pathology (LRP), and mixed pathology (ADP-LRP). OBJECTIVES: To determine the clinical phenotypes at the initial visit that are associated with the nature and severity of BPSDs in patients with ADP, LRP, and ADP-LRP. DESIGN, SETTING, AND PARTICIPANTS: This retrospective longitudinal cohort study included 2422 participants with neuropathologically confirmed ADP, LRP, or mixed ADP-LRP in the National Alzheimer Coordinating Center database from June 20, 2005, to September 4, 2019. Participants had a mean (SD) interval of 5.5 (2.8) years from initial visit to autopsy. MAIN OUTCOMES AND MEASURES: Clinician-determined diagnosis of change across 10 BPSDs (agitation, apathy, depression, delusions, disinhibition, auditory hallucinations, visual hallucinations, irritability, personality change, and rapid eye movement [REM] sleep behavior) and the highest severity score for behavioral change on the Neuropsychiatric Inventory Questionnaire (NPI-Q). RESULTS: A total of 2422 participants (1187 with ADP, 904 with ADP-LRP, and 331 with LRP) were included in the analysis (1446 men [59.7%]; mean [SD] age, 74.4 [10.1] years). Compared with initial amnestic symptoms, executive symptoms were associated with a higher risk for 7 of the 10 BPSDs (hazard ratio [HR] range, 1.28-2.45), and visuospatial symptoms were associated with a higher risk for 2 of the 10 BPSDs (HR range, 1.91-2.51), but neither were associated with a low risk for any BPSD. Language symptoms were associated with a low risk of onset for 3 of 10 BPSDs (HR range, 0.43-0.79) and a high risk for 1 BPSD (personality change) (HR, 1.42 [95% CI, 1.10-1.83]). Participants with LRP had a lower risk for agitation (HR, 0.74 [95% CI, 0.60-0.92]), disinhibition (HR, 0.78 [95% CI, 0.62-0.99]), and irritability (HR, 0.81 [95% CI, 0.68-0.96]) and a higher risk for apathy (HR, 1.19 [95% CI, 1.02-1.38]), depression (HR, 1.32 [95% CI, 1.12-1.55]), auditory (HR, 2.00 [95% CI, 1.37-2.93]) and visual (HR, 2.78 [95% CI, 2.21-3.49]) hallucinations, and REM sleep behavior changes (HR, 4.77 [95% CI, 3.61-6.31]) compared with the ADP group. The ADP-LRP group had a higher risk for delusions (HR, 1.27 [95% CI, 1.08-1.48]), auditory (HR, 1.62 [95% CI, 1.21-2.15]) and visual (HR, 1.57 [95% CI, 1.30-1.89]) hallucinations, and REM sleep behavior changes (HR, 2.10 [95% CI, 1.63-2.70]) than the ADP group and a lower risk for visual hallucinations (HR, 0.56 [95% CI, 0.45-0.71]) and REM sleep behavior changes (HR, 0.44 [95% CI, 0.34-0.57) than the LRP group. Overall, women showed a lower risk of agitation (HR, 0.86 [95% CI, 0.75-0.98]), apathy (HR, 0.79 [95% CI, 0.71-0.87]), visual hallucinations (HR, 0.76 [95% CI, 0.64-0.90]), irritability (HR, 0.77 [95% CI, 0.69-0.86]), and REM sleep behavior change (HR, 0.45 [95% CI, 0.35-0.58]) and a higher risk of depression (HR, 1.26 [95% CI, 1.13-1.41]). Older age was associated with a lower risk of most BPSDs (HR range, 0.98-0.99) except delusions (HR, 1.00 [95% CI, 1.00-1.01]) and auditory hallucinations (HR, 0.99 [95% CI, 0.97-1.00]) and a low NPI-Q composite score (ß = -0.07 [95% CI, -0.08 to -0.05]; P < .001). CONCLUSIONS AND RELEVANCE: These findings suggest that the risks of BPSDs differ with respect to the initial cognitive phenotype, underlying neuropathology, age, and sex. Awareness of these associations could be helpful in dementia management.

Temporal Ordering of Inflammatory Analytes sTNFR2 and sTREM2 in Relation to Alzheimer's Disease Biomarkers and Clinical Outcomes.

Inflammatory changes are among the key markers of Alzheimer's disease (AD) related pathological changes. Pro-inflammatory analytes have been related to cognitive decline while others have been related to attenuating neuronal death. Among them, changes in cerebrospinal fluid (CSF) levels of soluble triggering receptor expressed on myeloid cells 2 (sTREM2) and soluble tumor necrosis factor receptor 2 (sTNFR2) have been described as impacting favorable clinical outcomes in AD. We therefore evaluate the effect of CSF sTREM2 and sTNFR2 when taken together on AD biomarkers and longitudinal clinical decline to understand their relative role on impacting AD clinical biomarkers and subsequent clinical outcomes. This longitudinal observational cohort study included 168 amyloid-positive (A+) and p-tau-positive (T+) participants with mild cognitive impairment (MCI) or AD dementia from the Alzheimer's Disease Neuroimaging Initiative (ADNI) with 109 of them having concomitant CSF sTREM2 and sTNFR2 data and 48 A+ T+ participants with MCI from a tertiary memory clinic cohort. An exploratory analysis was performed using data from 86 cognitively normal (CN) participants from ADNI with 72 of them having concomitant CSF AD biomarkers and CSF sTREM2 and sTNFR2 data. General linear models were used to evaluate the effect of sTREM2 and sTNFR2 levels on baseline CSF Aß42, t-tau, and p-tau, and a linear mixed-effects model was used to assess longitudinal cognitive change after controlling for well-known covariates. Among ADNI A+ T+ MCI and AD dementia participants, CSF sTNFR2 had a stronger association, than CSF sTREM2, with CSF t-tau and p-tau. This was replicated among A+ T+ MCI participants from the memory clinic cohort. On the contrary, among A+ T+ CN participants, CSF sTREM2 explained significant variance in CSF t-tau and p-tau, while CSF sTNFR2 did not. When the effects of CSF sTNFR2 and t-tau on longitudinal cognitive change were taken into account, higher CSF sTREM2 predicted slower cognitive decline in A+ T+ AD dementia participants and faster decline in A+ T+ CN participants. Our results show that given the dynamic changes in sTREM2 and sTNFR2, the clinical impact of these distinct inflammation related biomarkers in tracking AD temporal progression across disease stages are likely to differ.

Hypertension and Hypercholesterolemia Modify Dementia Risk in Relation to APOEɛ4 Status.

BACKGROUND: There is significant interest in understanding the role of modifiable vascular risk factors contributing to dementia risk across age groups. OBJECTIVE: Risk of dementia onset was assessed in relation to vascular risk factors of hypertension and hypercholesterolemia among cognitively normal APOEɛ4 carriers and non-carriers. METHODS: In a sample of prospectively characterized longitudinal cohort from the National Alzheimer's Coordinating Center database, 9,349 participants met criteria for normal cognition at baseline, had a CDR-Global (CDR-G) score of zero, and had concomitant data on APOEɛ4 status and medical co-morbidities including histories of hypertension and hypercholesterolemia. Multivariable Cox proportional hazards models adjusted for well-known potential confounders were used to compare dementia onset among APOEɛ4 carriers and non-carriers by young (≤65 years) and old (> 65 year) age groups. RESULTS: 519 participants converted to dementia within an average follow up of 5.97 years. Among older APOEɛ4 carriers, hypercholesterolemia was related to lower risk of dementia (HR (95% CI), 0.68 (0.49-0.94), p = 0.02). Among older APOEɛ4 non-carriers, hypertension was related to higher risk of dementia (HR (95% CI), 1.44 (1.13-1.82), p = 0.003). These results were corroborated among a subset with autopsy data characterizing underlying neuropathology. Among younger participants, vascular risk factors did not impact dementia risk, likely from a lower frequency of vascular and Alzheimer's as etiologies of dementia among this cohort. CONCLUSION: A history of hypercholesterolemia related to a lower risk of dementia among older APOEɛ4 carriers, while hypertension related to a higher risk of dementia among older APOEɛ4 non-carriers.

Unique Sleep and Circadian Rhythm Dysfunction Neuroinflammatory and Immune Profiles in Alzheimer's Disease with Mild Cognitive Impairment.

Sleep dysfunction has been identified in the pathophysiology of Alzheimer's disease (AD); however, the role and mechanism of circadian rhythm dysfunction is less well understood. In a well-characterized cohort of patients with AD at the mild cognitive impairment stage (MCI-AD), we identify that circadian rhythm irregularities were accompanied by altered humoral immune responses detected in both the cerebrospinal fluid and plasma as well as alterations of cerebrospinal fluid biomarkers of neurodegeneration. On the other hand, sleep disruption was more so associated with abnormalities in circulating markers of immunity and inflammation and decrements in cognition.

TNFRSF1B Gene Variants and Related Soluble TNFR2 Levels Impact Resilience in Alzheimer's Disease.

Tumor necrosis factor receptor 2 (TNFR2) promotes neuronal survival downstream. This longitudinal study evaluated whether the TNFRSF1B gene encoding TNFR2 and levels of its soluble form (sTNFR2) affect Alzheimer disease (AD) biomarkers and clinical outcomes. Data analyzed included 188 patients in the Alzheimer's Disease Neuroimaging Initiative (ADNI) who had mild cognitive impairment (MCI) and AD dementia. Further, a replication study was performed in 48 patients with MCI with positive AD biomarkers who were treated at a memory clinic. Cerebrospinal fluid (CSF) sTNFR2 levels along with two related TNFRSF1B gene single nucleotide polymorphisms (SNPs) rs976881 and rs1061622 were assessed. General linear models were used to evaluate the effect of CSF sTNFR2 levels and each SNP in relationship to CSF t-tau and p-tau, cognitive domains, MRI brain measures, and longitudinal cognitive changes after adjustments were made for covariates such as APOE ε4 status. In the ADNI cohort, a significant interaction between rs976881 and CSF sTNFR2 modulates CSF t-tau and p-tau levels; hippocampal and whole brain volumes; and Digit Span Forwards subtest scores. In the replication cohort, a significant interaction between rs976881 and CSF sTNFR2 modulates CSF p-tau. A significant interaction between rs976881 and CSF sTNFR2 also impacts Clinical Dementia Rating Sum of Boxes scores over 12 months in the ADNI cohort. The interaction between TNFRSF1B variant rs976881 and CSF sTNFR2 levels was noted to modulate multiple AD-associated severity markers and cognitive domains. This interaction impacts resilience-related clinical outcomes in AD and lends support to sTNFR2 as a promising candidate for therapeutic targeting to improve clinical outcomes of interest.

Impact of APOE ε4 genotype on initial cognitive symptoms differs for Alzheimer's and Lewy body neuropathology.

BACKGROUND: APOE ε4 carrier status is known to increase odds of amnestic presentations with Alzheimer's pathology. It is unknown how APOE ε4 carrier status impacts odds of specific initial cognitive symptoms in the presence of Lewy body pathology. Here we evaluate the impact of APOE ε4 genotype on initial cognitive symptoms among those with Alzheimer's disease pathology (ADP) and Lewy-related pathology (LRP). METHODS: A retrospective cohort study of 2288 participants with neuropathology confirmed ADP or LRP in the National Alzheimer's Coordinating Center database, who had initial cognitive symptoms documented and had a Clinical Dementia Rating-Global (CDR-G) score ≤ 1 (cognitively normal, MCI, or early dementia). Unadjusted and adjusted logistic regression models taking into account age at evaluation, sex, and education examined the relationship between APOE ε4 genotype and initial symptoms (memory, executive, language visuospatial) among ADP with LRP and ADP-LRP groups. RESULTS: One thousand three hundred three participants met criteria for ADP alone, 90 for LRP alone, and 895 for co-existing ADP and LRP (ADP-LRP). Younger age increased odds of non-amnestic symptoms across all three groups. In the adjusted model among ADP, APOE ε4 carriers had higher odds of amnestic initial symptoms 1.5 [95% CI, 1.7-2.14, p = 0.003] and lower odds of initial language symptoms 0.67 [95% CI, 0.47-0.96, p = 0.03] than non-carriers. The odds for these two symptoms were not different between ADP and mixed ADP-LRP groups. Female sex and higher education increased odds of initial language symptoms in the ADP group in the adjusted model. In the unadjusted model, APOE ε4 carriers with LRP had a higher odds of visuospatial initial symptoms 21.96 [95% CI, 4.02-110.62, p < 0.0001], while no difference was noted for initial executive/attention symptoms. Among LRP, the odds of APOE ε4 on amnestic symptom was not significant; however, the interaction effect evaluating the difference in odds ratios of amnestic symptom between ADP and LRP groups also did not reach statistical significance. CONCLUSIONS: The odds of specific initial cognitive symptoms differed between ADP and LRP among APOE ε4 carriers compared to non-carriers. The odds of initial amnestic symptom was higher among ADP APOE ε4 carriers and the odds of visuospatial initial symptom was higher with LRP APOE ε4 carriers. This supports the hypothesis that APOE ε4 differentially impacts initial cognitive symptoms together with underlying neuropathology.

Spatial patterns of correlation between cortical amyloid and cortical thickness in a tertiary clinical population with memory deficit.

To estimate regional Alzheimer disease (AD) pathology burden clinically, analysis methods that enable tracking brain amyloid or tau positron emission tomography (PET) with magnetic resonance imaging (MRI) measures are needed. We therefore developed a robust MRI analysis method to identify brain regions that correlate linearly with regional amyloid burden in congruent PET images. This method was designed to reduce data variance and improve the sensitivity of the detection of cortical thickness-amyloid correlation by using whole brain modeling, nonlinear image coregistration, and partial volume correction. Using this method, a cross-sectional analysis of 75 tertiary memory clinic AD patients was performed to test our hypothesis that regional amyloid burden and cortical thickness are inversely correlated in medial temporal neocortical regions. Medial temporal cortical thicknesses were not correlated with their regional amyloid burden, whereas cortical thicknesses in the lateral temporal, lateral parietal, and frontal regions were inversely correlated with amyloid burden. This study demonstrates the robustness of our technique combining whole brain modeling, nonlinear image coregistration, and partial volume correction to track the differential correlation between regional amyloid burden and cortical thinning in specific brain regions. This method could be used with amyloid and tau PET to assess corresponding cortical thickness changes.

Correlation between brain volume and retinal photoreceptor outer segment volume in normal aging and neurodegenerative diseases.

PURPOSE: To investigate the association between outer retinal layer metrics, including photoreceptor outer segment volume, on spectral-domain optical coherence tomography (OCT) and brain volume on MRI in normal aging, Alzheimer's disease and Parkinson's disease. METHODS: This was an exploratory analysis of a cross-sectional cohort study that was approved by the Cleveland Clinic Institutional Review Board to evaluate neurodegenerative disorders. Subjects aged ≥ 50 were recruited. A comprehensive neurological exam, brain MRI with volumetric evaluation, and OCT were performed for each subject. Outer retinal layer parameters, including ellipsoid zone (EZ) to retinal pigment epithelium (RPE) volume (i.e., surrogate for panmacular photoreceptor outer segment volume), were evaluated with a novel OCT analysis platform. RESULTS: Of 85 subjects, 64 eyes of 64 subjects met MRI and OCT quality control criteria. Total brain volume (%ICV) significantly correlated with EZ-RPE volume in the normal cognition control group (n = 31, Pearson correlation coefficient 0.514, P < .01), the Parkinson's disease group (n = 19, Pearson correlation coefficient 0.482, P = .04), and the Alzheimer's dementia group (n = 14, Pearson correlation coefficient 0.526, P = .05). Multiple linear regression analysis revealed that photoreceptor outer segment (i.e., EZ-RPE) volume was an independent, influential factor on total brain volume in all study subjects (Coefficient 15.2, 95% confidence interval 7.8-22.6, P < .001). CONCLUSION: Outer retinal parameters on OCT may serve as a novel biomarker related to brain volume. This correlation was noted in control subjects suggesting a possible developmental link between retina and brain volume. This relationship was also maintained with atrophic neurodegenerative disorders. Further research is needed to explore possible threshold differences for underlying neurodegenerative disorders.

Inflammatory pathway analytes predicting rapid cognitive decline in MCI stage of Alzheimer's disease.

OBJECTIVE: To determine the inflammatory analytes that predict clinical progression and evaluate their performance against biomarkers of neurodegeneration. METHODS: A longitudinal study of MCI-AD patients in a Discovery cohort over 15 months, with replication in the Alzheimer's Disease Neuroimaging Initiative (ADNI) MCI cohort over 36 months. Fifty-three inflammatory analytes were measured in the CSF and plasma with a RBM multiplex analyte platform. Inflammatory analytes that predict clinical progression on Clinical Dementia Rating Scale-Sum of Boxes (CDR-SB) and Mini Mental State Exam scores were assessed in multivariate regression models. To provide context, key analyte results in ADNI were compared against biomarkers of neurodegeneration, hippocampal volume, and CSF neurofilament light (NfL), in receiver operating characteristic (ROC) analyses evaluating highest quartile of CDR-SB change over two years (≥3 points). RESULTS: Cerebrospinal fluid inflammatory analytes in relation to cognitive decline were best described by gene ontology terms, natural killer cell chemotaxis, and endothelial cell apoptotic process and in plasma, extracellular matrix organization, blood coagulation, and fibrin clot formation described the analytes. CSF CCL2 was most robust in predicting rate of cognitive change and analytes that correlated to CCL2 suggest IL-10 pathway dysregulation. The ROC curves for ≥3 points change in CDR-SB over 2 years when comparing baseline hippocampal volume, CSF NfL, and CCL2 were not significantly different. INTERPRETATION: Baseline levels of immune cell chemotactic cytokine CCL2 in the CSF and IL-10 pathway dysregulation impact longitudinal cognitive and functional decline in MCI-AD. CCL2's utility appears comparable to biomarkers of neurodegeneration in predicting rapid decline.

Highly Elevated Cerebrospinal Fluid Total Tau Level Reflects Higher Likelihood of Non-Amnestic Subtype of Alzheimer's Disease.

BACKGROUND: Cerebrospinal fluid (CSF) levels of total tau (t-tau) protein are thought to reflect the intensity of the neuronal damage in neurodegeneration, including Alzheimer's disease (AD). The recent link of CSF t-tau to rapidly progressive AD raises the question among other AD clinical variants regarding CSF t-tau. We investigated the clinical phenotypes of AD patients with varying CSF t-tau levels. OBJECTIVE: We tested the hypothesis that highly elevated CSF t-tau level would have a higher likelihood of presenting with atypical non-amnestic variants of AD. METHODS: Retrospective comparative case study of 97 patients evaluated in a memory clinic with clinical presentation and CSF biomarkers consistent with AD. We compared the age, sex, education, APOEɛ4 status, Montreal Cognitive Assessment (MoCA) score, clinical phenotype, and MRI volumetric measures by CSF t-tau quartile at baseline. Multivariable logistic regression models were used to evaluate if CSF t-tau levels predict non-amnestic presentations controlling for covariates. RESULTS: Non-amnestic AD had a higher median CSF t-tau level compared to amnestic-AD (p = 0.014). Each 50 pg/ml increase in CSF t-tau was associated with an increase in the odds of having a non-amnestic presentation (7.4%) and aphasia (10.6 %) as the initial presenting symptom even after taking into account; age, sex, education, APOEɛ4, MoCA, and CSF Aß42. Logopenic AD had higher t-tau and p-tau levels compared to other variants. CONCLUSIONS: Highly elevated CSF t-tau levels could indicate more cortical involvement presenting with early non-amnestic symptoms in atypical AD subtypes, particularly in the logopenic variant.

Key inflammatory pathway activations in the MCI stage of Alzheimer's disease.

OBJECTIVE: To determine the key inflammatory pathways that are activated in the peripheral and CNS compartments at the mild cognitive impairment (MCI) stage of Alzheimer's disease (AD). METHODS: A cross-sectional study of patients with clinical and biomarker characteristics consistent with MCI-AD in a discovery cohort, with replication in the Alzheimer's Disease Neuroimaging Initiative (ADNI) cohort. Inflammatory analytes were measured in the CSF and plasma with the same validated multiplex analyte platform in both cohorts and correlated with AD biomarkers (CSF Aß42, total tau (t-tau), phosphorylated tau (p-tau) to identify key inflammatory pathway activations. The pathways were additionally validated by evaluating genes related to all analytes in coexpression networks of brain tissue transcriptome from an autopsy confirmed AD cohort to interrogate if the same pathway activations were conserved in the brain tissue gene modules. RESULTS: Analytes of the tumor necrosis factor (TNF) signaling pathway (KEGG ID:4668) in the CSF and plasma best correlated with CSF t-tau and p-tau levels, and analytes of the complement and coagulation pathway (KEGG ID:4610) best correlated with CSF Aß42 levels. The top inflammatory signaling pathways of significance were conserved in the peripheral and the CNS compartments. They were also confirmed to be enriched in AD brain transcriptome gene clusters. INTERPRETATION: A cell-protective rather than a proinflammatory analyte profile predominates in the CSF in relation to neurodegeneration markers among MCI-AD patients. Analytes from the TNF signaling and the complement and coagulation pathways are relevant in evaluating disease severity at the MCI stage of AD.

Amygdala sign, a FDG-PET signature of dementia with Lewy Bodies.

BACKGROUND: Biomarkers are being used increasingly to support the diagnosis of dementia with Lewy bodies (DLB). Novel biomarkers that increase diagnostic specificity of DLB are needed. We assessed previously known FDG-PET occipital cortex hypometabolism, and cingulate island sign biomarkers of DLB against a novel amygdala signature. METHODS: Retrospective analysis of 49 patients evaluated at one tertiary memory clinic. All had a FDG-PET brain scan performed as part of their diagnostic work up evaluating three common neurodegenerative etiologies: Alzheimer dementia (AD), Frontotemporal dementia (FTD) and DLB. A consensus diagnosis of dementia was made based on accepted clinical criteria for AD, FTD and DLB. FDG-PET regional metabolism was delineated by automatic segmentation as well as manual tracing of amygdala and posterior cingulate volumes of interest. Mean normalized values calculated for regional FDG-PET signatures of DLB: occipital cortex hypometabolism and preservation of posterior cingulate and amygdala metabolism relative to whole brain metabolism were evaluated. RESULTS: Significant overlap between DLB and AD patients (occipital, parietal, temporal and frontal hypometabolism) and between DLB and FTD (frontal hypometabolism and the posterior cingulate sign) were identified. Right amygdala (p = 0.028) and right posterior cingulate (p = 0.035) mean normalized regional metabolism levels were preserved in DLB compared to AD. Among subjects at less advanced stages of dementia (MoCA>10), relative preservation of regional metabolism was notable across both left (p = 0.006) and right (p = 0.020) amygdala. CONCLUSION: Relative preservation of amygdala metabolism could complement previously described FDG-PET findings in earlier stages of DLB.