Erica Christen

Performance-Based Measures of Everyday Function in Mild Cognitive Impairment

OBJECTIVE The view that everyday function is preserved in mild cognitive impairment may be problematic. The objectives of this study were to determine the magnitude of impairment in everyday function in patients with mild cognitive impairment and Alzheimers disease using a novel sensitive performance-based measure (the UCSD Performance-Based Skills Assessment; UPSA), contrast it with use of an informant-based measure (the Alzheimers Disease Cooperative Study-Activities of Daily Living Inventory; ADCS-ADL), and model the relationship between cognitive measures and the performance-based measure. METHOD Fifty cognitively normal elders, 26 patients who met criteria for amnestic mild cognitive impairment, and 22 patients who suffered from mild to moderate Alzheimers disease were assessed on the UPSA, the ADCS-ADL, and a battery of neurocognitive tests. RESULTS Patients with mild cognitive impairment had significant impairments on the UPSA but not on the ADCS-ADL. The magnitude of the effect size between the cognitively healthy and the mild cognitive impairment group for the UPSA was large (d=0.86). A strong and significant relationship was observed between cognitive performances in speed (R(2)=0.37), episodic memory (R(2)=0.10), and semantic processing (R(2)=0.03) and UPSA score using multiple regression models. The psychometric properties of the UPSA were acceptable, as were its sensitivity and specificity in contrasts between cognitively normal elders and patients with mild cognitive impairment and between the latter group and patients with Alzheimers disease. CONCLUSIONS These findings indicate that performance-based measures of function may be a sensitive tool in studies of Alzheimers disease and mild cognitive impairment and suggest the need for a reconceptualization of the relationship between cognition and function in mild cognitive impairment so that they can be usefully aligned.

Endocannabinoids in Alzheimer's disease and their impact on normative cognitive performance: a case-control and cohort study

BackgroundNeuropathological, animal, and cell culture studies point to a role for the bodys own endogenous cannabinoids (eCBs) system in Alzheimers disease (AD) pathology and treatment. To date, no published studies have investigated the potential utility of circulating eCBs as diagnostic biomarkers for AD or the impact of central eCBs on cognition.ResultsIn comparison with healthy controls, there were no significant differences in measured eCB concentrations in plasma samples from patients with AD. Detectable eCBs in cerebrospinal fluid (CSF) had no relationship to cognitive performance in healthy controls at risk for AD. In pooled plasma samples, an inverse correlation was observed between plasma levels of the eCB 2-AG (2-arachidonoylglycerol) and TNF-α (r = -0.41, p < 0.02).ConclusionThese results suggest that circulating endocannabinoids do not have utility as diagnostic biomarkers for AD and do not have a robust correlation with cognitive performance. Circulating levels of 2-AG may downregulate TNF-α production.

Relationships Between Behavioral Syndromes and Cognitive Domains in Alzheimer Disease: The Impact of Mood and Psychosis

OBJECTIVES Behavioral disturbances occur in nearly all Alzheimer disease (AD) patients together with an array of cognitive impairments. Prior investigations have failed to demonstrate specific associations between them, suggesting an independent, rather than shared, pathophysiology. The objective of this study was to reexamine this issue using an extensive cognitive battery together with a sensitive neurobehavioral and functional rating scale to correlate behavioral syndromes and cognitive domains across the spectrum of impairment in dementia. DESIGN Cross-sectional study of comprehensive cognitive and behavioral ratings in subjects with AD and mild cognitive impairment. SETTING Memory disorders research center. PARTICIPANTS Fifty subjects with AD and 26 subjects with mild cognitive impairment; and their caregivers. MEASUREMENTS Cognitive rating scales administered included the Mini-Mental State Examination; the Modified Mini-Mental State Examination; the Boston Naming Test; the Benton Visual Retention Test; the Consortium to Establish a Registry for Alzheimers Disease Neuropsychology Assessment; the Controlled Oral Word Test; the Wechsler Memory Scale logical memory I and logical memory II task; the Wechsler Memory Scale-Revised digit span; the Wechsler Adult Intelligence Scale-Revised digit symbol task; and the Clock Drawing Task together with the Clinical Dementia Rating Scale and the Neuropsychiatric Inventory. RESULTS Stepwise regression of cognitive domains with symptom domains revealed significant associations of mood with impaired executive function/speed of processing (Δr = 0.22); impaired working memory (Δr = 0.05); impaired visual memory (Δr = 0.07); and worsened Clinical Dementia Rating Scale (Δr = 0.08). Psychosis was significantly associated with impaired working memory (Δr = 0.13). CONCLUSIONS Mood symptoms appear to impact diverse cognitive realms and to compromise functional performance. Among neuropsychological indices, the unique relationship between working memory and psychosis suggests a possible common underlying neurobiology.

Psychosis in Alzheimer's Disease is Associated with Frontal Metabolic Impairment and Accelerated Decline in Working Memory: Findings from the Alzheimer's Disease Neuroimaging Initiative

OBJECTIVE An ascendant body of evidence suggests that Alzheimer disease with psychosis (AD+P) is a distinct variant of illness with its own genetic diathesis and a unique clinical course. Impaired frontal lobe function has been previously implicated in AD+P. The current exploratory study, presented in two parts, evaluates both the regional brain metabolic and psychometric correlates of psychosis in a longitudinal sample of subjects with AD, made available by the Alzheimers Disease Neuroimaging Initiative (ADNI). METHODS In Part 1 of the study, 21 ADNI participants with AD who developed psychotic symptoms during the study but were not psychotic at baseline were matched with 21 participants with AD who never became psychotic during the study period, and mean brain [F(18)]fluorodeoxyglucose positron emission tomography (FDG-PET) Cerebral metabolic rate for glucose (CMRgl) by regions of interest (ROIs) were compared Additionally, 39 participants with active psychosis at the time of image acquisition were matched with 39 participants who were never psychotic during the study period, and mean brain FDG-PET CMRgl by sROI were compared. In Part 2 of the study, 354 ADNI participants with AD who were followed for 24 months with serial psychometric testing were identified, and cognitive performance and decline were evaluated for correlation with psychotic symptoms. RESULTS Part 1: There were no regional brain metabolic differences between those with AD destined to become psychotic and those who did not become psychotic. There was a significant reduction in mean orbitofrontal brain metabolism in those with active psychosis. Part 2: Over the course of study follow-up, psychosis was associated with accelerated decline in functional performance as measured by the Functional Assessment Questionnaire, the Mini-Mental State Examination, and Forward Digit Span. CONCLUSION In a sample drawn from the ADNI dataset, our exploratory FDG-PET findings and longitudinal cognitive outcomes support the hypofrontality model of AD+P. Focal frontal vulnerability may mediate the accelerated decline seen in AD+P.

APOE Genotype Modulates Proton Magnetic Resonance Spectroscopy Metabolites in the Aging Brain

BACKGROUND Proton magnetic resonance spectroscopy ((1)H-MRS) studies on healthy aging have reported inconsistent findings and have not systematically taken into account the possible modulatory effect of APOE genotype. We aimed to quantify brain metabolite changes in healthy subjects in relation to age and the presence of the APOE E4 genetic risk factor for Alzheimers disease. Additionally, we examined these measures in relation to cognition. METHODS We studied a cohort of 112 normal adults between 50 and 86 years old who were genotyped for APOE genetic polymorphism. Measurements of (1)H-MRS metabolites were obtained in the posterior cingulate and precuneus region. Measures of general cognitive functioning, memory, executive function, semantic fluency, and speed of processing were also obtained. RESULTS General linear model analysis demonstrated that older APOE E4 carriers had significantly higher choline/creatine and myo-inositol/creatine ratios than APOE E3 homozygotes. Structural equation modeling resulted in a model with an excellent goodness of fit and in which the APOE × age interaction and APOE status each had a significant effect on (1)H-MRS metabolites (choline/creatine and myo-inositol/creatine). Furthermore, the APOE × age variable modulation of cognition was mediated by (1)H-MRS metabolites. CONCLUSIONS In a healthy aging normal population, choline/creatine and myo-inositol/creatine ratios were significantly increased in APOE E4 carriers, suggesting the presence of neuroinflammatory processes and greater membrane turnover in older carriers. Structural equation modeling analysis confirmed these possible neurodegenerative markers and also indicated the mediator role of these metabolites on cognitive performance among older APOE E4 carriers.

An Open-Label Exploratory Study with Memantine: Correlation between Proton Magnetic Resonance Spectroscopy and Cognition in Patients with Mild to Moderate Alzheimer's Disease.

Aim: To characterize progression of Alzheimer’s disease (AD) using proton magnetic resonance spectroscopy (1H MRS). Methods: Eleven subjects with mild to moderate AD underwent neurocognitive testing and single-voxel 1H MRS from the precuneus and posterior cingulate region at baseline, after 24 weeks of monotherapy with a cholinesterase inhibitor, and after another 24 weeks of combination therapy with open-label memantine and a cholinesterase inhibitor. Baseline metabolites [N-acetylaspartate (NAA), myo-inositol (mI), choline (Cho), and creatine (Cr)] and their ratios in AD subjects were compared with those of an age-matched control group of 28 cognitively normal subjects. Results: AD subjects had significantly higher mI/Cr and lower NAA, NAA/Cr, NAA/Cho, and NAA/mI. Baseline Alzheimer’s Disease Cooperative Study Activities of Daily Living (ADCS-ADL) scores significantly correlated with NAA/Cr, mI/Cr, and NAA/mI. There was an increase in mI and a decrease in NAA/mI, but no significant change in other metabolites or ratios, or neurocognitive measures, when memantine was added to a cholinesterase inhibitor. Conclusion: Metabolite ratios significantly differed between AD and control subjects. Baseline metabolite ratios correlated with function (ADCS-ADL). There was an increase in mI and a decrease in NAA/mI, but no changes in other metabolites, ratios, or cognitive measures, when memantine was added to a cholinesterase inhibitor.

Pilot Study of Mycophenolate Mofetil for Treatment of Kidney Disease due to Congenital Urinary Tract Disorders in Children

BACKGROUND Congenital uropathies account for nearly half the chronic kidney disease in children. Immune-mediated injury may contribute to progressive loss of kidney function in affected patients. STUDY DESIGN Open-label uncontrolled pilot study to determine the feasibility of treatment with the immunosuppressive drug mycophenolate mofetil (MMF) to prevent a decrease in kidney function in pediatric patients with congenital uropathies. SETTING & PARTICIPANTS Children treated in an outpatient tertiary-care center were eligible if they had: (1) age of 3 to 16 years, (2) glomerular filtration rate (GFR) less than 50 mL/min/1.73 m(2), and (3) a congenital genitourinary tract abnormality. INTERVENTION After a 2-month run-in period, patients were prescribed MMF, 600 mg/m(2)/dose, twice daily for a 24-month treatment period. OUTCOMES The primary end point was feasibility based on the ability to recruit and retain subjects and lack of unanticipated adverse events. The secondary end point was change in GFR. MEASUREMENTS Patients were monitored by using standard clinical laboratory tests, and GFR was determined by means of iothalamate clearance. RESULTS 12 patients aged 8.9 +/- 4.8 years (10 boys, 2 girls) were treated with MMF for 18.6 +/- 8.0 months; 7 patients completed the entire treatment period. MMF dosage at the final study visit was 381 +/- 241 mg/m(2) twice daily. Gastrointestinal symptoms were the most common adverse effect. There was only 1 serious adverse event, an episode of fever and neutropenia requiring parenteral antibiotic therapy after 21 months of MMF therapy. GFR remained stable throughout the treatment period. Nutritional status, blood pressure, and serum calcium, phosphorus, and cholesterol levels were unchanged during this period. LIMITATIONS Insufficient power to assess the safety or efficacy of MMF therapy for patients with congenital uropathies. CONCLUSION It is feasible to study MMF as an adjunctive therapy to retard the progression of kidney disease in children with congenital uropathies. A multicenter randomized clinical trial is warranted to determine the efficacy of this novel treatment strategy.

Tacrolimus rescues the signaling and gene expression signature of endothelial ALK1 loss-of-function and improves HHT vascular pathology

Hereditary hemorrhagic telangiectasia (HHT) is a highly debilitating and life-threatening genetic vascular disorder arising from endothelial cell (EC) proliferation and hypervascularization, for which no cure exists. Because HHT is caused by loss-of-function mutations in bone morphogenetic protein 9 (BMP9)-ALK1-Smad1/5/8 signaling, interventions aimed at activating this pathway are of therapeutic value. We interrogated the whole-transcriptome in human umbilical vein ECs (HUVECs) and found that ALK1 signaling inhibition was associated with a specific pro-angiogenic gene expression signature, which included a significant elevation of DLL4 expression. By screening the NIH clinical collections of FDA-approved drugs, we identified tacrolimus (FK-506) as the most potent activator of ALK1 signaling in BMP9-challenged C2C12 reporter cells. In HUVECs, tacrolimus activated Smad1/5/8 and opposed the pro-angiogenic gene expression signature associated with ALK1 loss-of-function, by notably reducing Dll4 expression. In these cells, tacrolimus also inhibited Akt and p38 stimulation by vascular endothelial growth factor, a major driver of angiogenesis. In the BMP9/10-immunodepleted postnatal retina-a mouse model of HHT vascular pathology-tacrolimus activated endothelial Smad1/5/8 and prevented the Dll4 overexpression and hypervascularization associated with this model. Finally, tacrolimus stimulated Smad1/5/8 signaling in C2C12 cells expressing BMP9-unresponsive ALK1 HHT mutants and in HHT patient blood outgrowth ECs. Tacrolimus repurposing has therefore therapeutic potential in HHT.

The Relational and Item-Specific Encoding Task in Mild Cognitive Impairment and Alzheimer Disease

Background: The Relational and Item-Specific Encoding task (RISE) measures episodic memory subcomponents, including item-specific and relational encoding of to-be-remembered stimuli. These memory components are neurobiologically relevant because they may engage distinct subregions of the medial temporal lobe, perirhinal and entorhinal cortices, parahippocampus, and hippocampus. Methods: A total of 125 participants, including 84 healthy controls (HC), 22 mild cognitive impairment-diagnosed and 19 Alzheimer disease (AD)-diagnosed participants, were administered the RISE and neuropsychological measures. Stepwise linear regressions assessed prediction of functional ability from RISE d′ measures. ANOVAs and logistic regressions determined the ability of the RISE to discriminate between the diagnostic groups. In addition, the psychometric properties of the RISE were examined. Results: RISE measures predicted diagnosis with pseudo R2 values in the range of 0.25-0.30. Receiver operating characteristic curves demonstrated adequate sensitivity and specificity with areas under the curve in the range of 0.78-0.98. Memory following relational encoding was a significant predictor of everyday functional competence. The RISE had acceptable psychometric properties, with the exception of floor effects in the AD group. Conclusion: The RISE measures significantly predicted diagnosis and predicted everyday functional competence. The RISE offers unique advantages in the assessment of HC and individuals with preclinical AD.

Tacrolimus Rescues Endothelial ALK1 Loss-Of-Function Signaling And Improves HHT Vascular Pathology

Hereditary hemorrhagic telangiectasia (HHT) is a genetic vascular disorder arising from endothelial cell (EC) proliferation and hypervascularization, for which no cure exists. Because HHT is caused by loss-of-function mutations in BMP9-ALK1-Smad1/5/8 signaling, interventions aimed at activating this pathway are of therapeutic value. By screening FDA-approved drug libraries, we identified tacrolimus (FK-506) as a potent activator of Smad1/5/8 in BMP9-challenged reporter cells. In primary ECs, tacrolimus activated Smad1/5/8 to oppose the pro-angiogenic gene expression signature associated with ALK1 loss-of-function, by notably reducing Dll4 expression. In these cells, tacrolimus also inhibited Akt and p38 stimulation by VEGF. In the BMP9/10-immunodepleted postnatal retina—a mouse model of HHT vascular pathology—tacrolimus activated endothelial Smad1/5/8 and prevented the Dll4 overexpression and hypervascularization associated with this model. Finally, tacrolimus stimulated Smad1/5/8 in cells transfected with BMP9-unresponsive ALK1 HHT mutants and in HHT patient blood outgrowth ECs. We propose that tacrolimus repurposing has therapeutic potential in HHT.