WarpDrive: Improving spatial normalization using manual refinements.

Spatial normalization-the process of mapping subject brain images to an average template brain-has evolved over the last 20+ years into a reliable method that facilitates the comparison of brain imaging results across patients, centers & modalities. While overall successful, sometimes, this automatic process yields suboptimal results, especially when dealing with brains with extensive neurodegeneration and atrophy patterns, or when high accuracy in specific regions is needed. Here we introduce WarpDrive, a novel tool for manual refinements of image alignment after automated registration. We show that the tool applied in a cohort of patients with Alzheimer's disease who underwent deep brain stimulation surgery helps create more accurate representations of the data as well as meaningful models to explain patient outcomes. The tool is built to handle any type of 3D imaging data, also allowing refinements in high-resolution imaging, including histology and multiple modalities to precisely aggregate multiple data sources together.

Diagnosing and Treating Alzheimer Disease During the Early Stage.

Recent advances in technology can lead to earlier detection of Alzheimer disease (AD) in patients and therefore opportunities for early diagnosis and treatment. In addition, novel agents can slow disease progression and improve symptoms. However, clinicians are not providing a diagnosis to over half of individuals who meet criteria for dementia. Early detection and intervention are crucial to slow symptom progression, and these advances provide a window of opportunity to diagnose the disease early and even prevent it from becoming symptomatic. Clinicians need education on early recognition of AD and on sharing the diagnosis of AD with patients and families as well as guidance for providing patients and families with information on next steps and facilitating early treatment initiation for AD. Partnering with clinicians in the primary care setting and providing them with the necessary tools can change the trajectory of the disease for patients and caregivers.

Optimal deep brain stimulation sites and networks for stimulation of the fornix in Alzheimer's disease.

Deep brain stimulation (DBS) to the fornix is an investigational treatment for patients with mild Alzheimer's Disease. Outcomes from randomized clinical trials have shown that cognitive function improved in some patients but deteriorated in others. This could be explained by variance in electrode placement leading to differential engagement of neural circuits. To investigate this, we performed a post-hoc analysis on a multi-center cohort of 46 patients with DBS to the fornix (NCT00658125, NCT01608061). Using normative structural and functional connectivity data, we found that stimulation of the circuit of Papez and stria terminalis robustly associated with cognitive improvement (R = 0.53, p < 0.001). On a local level, the optimal stimulation site resided at the direct interface between these structures (R = 0.48, p < 0.001). Finally, modulating specific distributed brain networks related to memory accounted for optimal outcomes (R = 0.48, p < 0.001). Findings were robust to multiple cross-validation designs and may define an optimal network target that could refine DBS surgery and programming.

Timely Diagnosis of Alzheimer Disease.

Diagnosing early-stage Alzheimer disease can lead to prompt initiation of treatment and slow down symptom progression. However, clinicians are not providing a diagnosis to over half of individuals who meet criteria for dementia. Tests for biomarkers, new symptomatic treatments and disease-modifying agents, and the addition of the preclinical stage to the diagnostic criteria for AD can aid in earlier disease recognition and developing treatment plans. Communicating diagnosis and information on next steps with patients and caregivers can lead to patient and caregiver involvement in decision-making and planning as well as participation in clinical trials and maximizing benefits and lifestyle interventions.

Facilitating Treatment Initiation in Early-Stage Alzheimer Disease.

Once a diagnosis of Alzheimer disease is established, a wide variety of therapy options are available to treat different stages of the disease. Patients have the opportunity to delay onset of the disease or delay its progression if diagnosed early enough through new FDA-approved disease-modifying treatments. For mild to moderate stages, new symptomatic treatments can slow the progression of the disease and improve symptoms. A multi-component approach is recommended in order to tailor treatments to each patient's needs.

Safety, Tolerability, and Immunogenicity of the ACI-24 Vaccine in Adults With Down Syndrome: A Phase 1b Randomized Clinical Trial.

Importance: Individuals with Down syndrome (DS) are at high risk of developing Alzheimer disease due to an increased dose of the amyloid precursor protein gene, APP, which leads to increased levels of full-length APP and its products, including amyloid-ß (Aß). The liposome-based antiamyloid ACI-24 vaccine is intended to treat neurological disorders caused by misfolded Aß pathological protein. However, the safety, tolerability, and immunogenicity of the ACI-24 vaccine among adults with DS have not been fully examined. Objective: To assess the safety and tolerability of the ACI-24 vaccine among adults with DS as well as its ability to induce immunogenicity measured by anti-Aß immunoglobulin G titers. Design, Setting, and Participants: This multicenter double-blind placebo-controlled dose-escalation phase 1b randomized clinical trial was conducted at 3 US academic medical centers with affiliated Down syndrome clinics between March 30, 2016, and June 29, 2020. A total of 20 adults with DS were screened; of those, 16 adults were eligible to participate. Eligibility criteria included men or women aged 25 to 45 years with cytogenetic diagnosis of either trisomy 21 or complete unbalanced translocation of chromosome 21. Between April 27, 2016, and July 2, 2018, participants were randomized 3:1 into 2 dose-level cohorts (8 participants per cohort, with 6 participants receiving the ACI-24 vaccine and 2 receiving placebo) in a 96-week study. Participants received 48 weeks of treatment followed by an additional 48 weeks of safety follow-up. Interventions: Participants were randomized to receive 7 subcutaneous injections of ACI-24, 300 µg or 1000 µg, or placebo. Main Outcomes and Measures: Primary outcomes were measures of safety and tolerability as well as antibody titers. Results: Among 16 enrolled participants, the mean (SD) age was 32.6 (4.4) years; 9 participants were women, and 7 were men. All participants were White, and 1 participant had Hispanic or Latino ethnicity. Treatment adherence was 100%. There were no cases of meningoencephalitis, death, or other serious adverse events (AEs) and no withdrawals as a result of AEs. Most treatment-emergent AEs were of mild intensity (110 of 132 events [83.3%]) and unrelated or unlikely to be related to the ACI-24 vaccine (113 of 132 events [85.6%]). No amyloid-related imaging abnormalities with edema or cerebral microhemorrhage and no evidence of central nervous system inflammation were observed on magnetic resonance imaging scans. Increases in anti-Aß immunoglobulin G titers were observed in 4 of 12 participants (33.3%) receiving ACI-24 (2 receiving 300 µg and 2 receiving 1000 µg) compared with 0 participants receiving placebo. In addition, a greater increase was observed in plasma Aß1-40 and Aß1-42 levels among individuals receiving ACI-24. Conclusions and Relevance: In this study, the ACI-24 vaccine was safe and well tolerated in adults with DS. Evidence of immunogenicity along with pharmacodynamic and target engagement were observed, and anti-Aß antibody titers were not associated with any adverse findings. These results support progression to clinical trials using an optimized formulation of the ACI-24 vaccine among individuals with DS. Trial Registration: ClinicalTrials.gov Identifier: NCT02738450.

Effect of Age on Clinical Trial Outcome in Participants with Probable Alzheimer's Disease.

BACKGROUND: Age may affect treatment outcome in trials of mild probable Alzheimer's disease (AD). OBJECTIVE: We examined age as a moderator of outcome in an exploratory study of deep brain stimulation targeting the fornix (DBS-f) region in participants with AD. METHODS: Forty-two participants were implanted with DBS electrodes and randomized to double-blind DBS-f stimulation ("on") or sham DBS-f ("off") for 12 months. RESULTS: The intervention was safe and well tolerated. However, the selected clinical measures did not differentiate between the "on" and "off" groups in the intent to treat (ITT) population. There was a significant age by time interaction with the Alzheimer's Disease Assessment Scale; ADAS-cog-13 (p = 0.028). Six of the 12 enrolled participants < 65 years old (50%) markedly declined on the ADAS-cog-13 versus only 6.7%of the 30 participants≥65 years old regardless of treatment assignment (p = 0.005). While not significant, post-hoc analyses favored DBS-f "off" versus "on" over 12 months in the < 65 age group but favored DBS-f "on" versus "off" in the≥65 age group on all clinical metrics. On the integrated Alzheimer's Disease rating scale (iADRS), the effect size contrasting DBS-f "on" versus "off" changed from +0.2 (favoring "off") in the < 65 group to -0.52 (favoring "on") in the≥65 age group. CONCLUSION: The findings highlight issues with subject selection in clinical trials for AD. Faster disease progression in younger AD participants with different AD sub-types may influence the results. Biomarker confirmation and genotyping to differentiate AD subtypes is important for future clinical trials.

Treatment Challenges and the Hope of Emerging Therapies in Early-Stage Alzheimer Disease.

Alzheimer disease (AD), the most common cause of dementia, is a degenerative brain disease with no cure. In the United States alone, an estimated 5.8 million people are living with AD. More than half of individuals living with AD and other dementias are not getting an accurate diagnosis and, when they do receive one, clinicians are not effectively communicating with patients and care partners regarding the illness and next steps. Additionally, prompt treatment initiation does not occur in a substantial number of newly diagnosed patients. This Academic Highlights addresses best practices for identifying patients with early-stage AD, discussing treatment goals and challenges with patients who have AD and their care partners, employing current medications approved by the U.S. Food and Drug Administration to slow symptom progression, and staying informed about emerging therapies that offer new hope for disease modification.

Talking With Patients and Care Partners About Treatment Goals and Challenges in Early-Stage Alzheimer Disease.

Alzheimer disease (AD) requires timely diagnosis and treatment initiation as early as possible to delay further loss of functioning. Clinicians must attempt to answer patients' and care partners' questions about treatment goals and expected challenges. In this webcast, Drs Burke and Apostolova address topics critical to the care of patients with early-stage AD. They highlight barriers to diagnosis, describe genetic risk factors, and emphasize the role of neuropsychologic testing. Drs Burke and Apostolova agree that, although current medications slow symptom progression associated with AD, emerging therapies offer hope for disease modification. These experts also talk about important conversations to have with patients and their care partners, such as about diet, exercise, driving, and plans for the later stage of illness.

Can Emerging Therapies Resolve Unmet Needs With Current Treatment in Early-Stage Alzheimer Disease?

While no current medications for Alzheimer disease (AD) can modify the disease, the agents do slow symptom progression. The earlier the medications are started for patients diagnosed with AD, the greater the potential benefit. Clinical trials are in progress on drugs with a variety of mechanisms that may modulate the disease course: neuronal protection; protein synthesis or aggregation inhibition; immunologic priming with antibodies; vaccines; and secretase inhibition. Early diagnosis, whether in the primary care setting or the specialty setting, continues to be critical to give patients their best chance at managing their illness. Although current treatments cannot give patients back what they have already lost, in the near future, drugs may be able to slow or even halt their cognitive and functional decline if clinicians identify AD early enough in the disease process.

Cross-Sectional Exploration of Plasma Biomarkers of Alzheimer's Disease in Down Syndrome: Early Data from the Longitudinal Investigation for Enhancing Down Syndrome Research (LIFE-DSR) Study.

With improved healthcare, the Down syndrome (DS) population is both growing and aging rapidly. However, with longevity comes a very high risk of Alzheimer's disease (AD). The LIFE-DSR study (NCT04149197) is a longitudinal natural history study recruiting 270 adults with DS over the age of 25. The study is designed to characterize trajectories of change in DS-associated AD (DS-AD). The current study reports its cross-sectional analysis of the first 90 subjects enrolled. Plasma biomarkers phosphorylated tau protein (p-tau), neurofilament light chain (NfL), amyloid ß peptides (Aß1-40, Aß1-42), and glial fibrillary acidic protein (GFAP) were undertaken with previously published methods. The clinical data from the baseline visit include demographics as well as the cognitive measures under the Severe Impairment Battery (SIB) and Down Syndrome Mental Status Examination (DS-MSE). Biomarker distributions are described with strong statistical associations observed with participant age. The biomarker data contributes to understanding DS-AD across the spectrum of disease. Collectively, the biomarker data show evidence of DS-AD progression beginning at approximately 40 years of age. Exploring these data across the full LIFE-DSR longitudinal study population will be an important resource in understanding the onset, progression, and clinical profiles of DS-AD pathophysiology.

Mapping autonomic, mood and cognitive effects of hypothalamic region deep brain stimulation.

Because of its involvement in a wide variety of cardiovascular, metabolic and behavioural functions, the hypothalamus constitutes a potential target for neuromodulation in a number of treatment-refractory conditions. The precise neural substrates and circuitry subserving these responses, however, are poorly characterized to date. We sought to retrospectively explore the acute sequelae of hypothalamic region deep brain stimulation and characterize their neuroanatomical correlates. To this end we studied-at multiple international centres-58 patients (mean age: 68.5 ± 7.9 years, 26 females) suffering from mild Alzheimer's disease who underwent stimulation of the fornix region between 2007 and 2019. We catalogued the diverse spectrum of acutely induced clinical responses during electrical stimulation and interrogated their neural substrates using volume of tissue activated modelling, voxel-wise mapping, and supervised machine learning techniques. In total 627 acute clinical responses to stimulation-including tachycardia, hypertension, flushing, sweating, warmth, coldness, nausea, phosphenes, and fear-were recorded and catalogued across patients using standard descriptive methods. The most common manifestations during hypothalamic region stimulation were tachycardia (30.9%) and warmth (24.6%) followed by flushing (9.1%) and hypertension (6.9%). Voxel-wise mapping identified distinct, locally separable clusters for all sequelae that could be mapped to specific hypothalamic and extrahypothalamic grey and white matter structures. K-nearest neighbour classification further validated the clinico-anatomical correlates emphasizing the functional importance of identified neural substrates with area under the receiving operating characteristic curves between 0.67 and 0.91. Overall, we were able to localize acute effects of hypothalamic region stimulation to distinct tracts and nuclei within the hypothalamus and the wider diencephalon providing clinico-anatomical insights that may help to guide future neuromodulation work.

Brain structures and networks responsible for stimulation-induced memory flashbacks during forniceal deep brain stimulation for Alzheimer's disease.

INTRODUCTION: Fornix deep brain stimulation (fx-DBS) is under investigation for treatment of Alzheimer's disease (AD). We investigated the anatomic correlates of flashback phenomena that were reported previously during acute diencephalic stimulation. METHODS: Thirty-nine patients with mild AD who took part in a prior fx-DBS trial (NCT01608061) were studied. After localizing patients' implanted electrodes and modeling the volume of tissue activated (VTA) by DBS during systematic stimulation testing, we performed (1) voxel-wise VTA mapping to identify flashback-associated zones; (2) machine learning-based prediction of flashback occurrence given VTA overlap with specific structures; (3) normative functional connectomics to define flashback-associated brain-wide networks. RESULTS: A distinct diencephalic region was associated with greater flashback likelihood. Fornix, bed nucleus of stria terminalis, and anterior commissure involvement predicted memory events with 72% accuracy. Flashback-inducing stimulation exhibited greater functional connectivity to a network of memory-evoking and autobiographical memory-related sites. DISCUSSION: These results clarify the neuroanatomical substrates of stimulation-evoked flashbacks.

Diagnosing and Treating Depression in Patients with Alzheimer's Disease.

Although cognitive and functional impairment are the hallmark features of Alzheimer's disease (AD), neuropsychiatric symptoms associated with AD account for increased rates of disability and profoundly impact the quality of life of both patients and their caregivers. This narrative review of current evidence provides practical guidance in diagnosing and managing depression in patients with AD using pharmacological and nonpharmacological interventions. After apathy, depression is the second most common neuropsychiatric symptom in AD. Diagnosing late-life depression (LLD), particularly in those affected by AD, is complicated because older patients may not meet the criteria for a major depressive disorder. Clinically, late-life depression and dementia can be indistinguishable. Although these two entities are now thought to be related, the pathologic mechanisms remain unclear. Evidence suggests that LLD may be a prodromal symptom of neurodegenerative disease. The various geropsychiatric measures currently used to diagnose, rate the severity of, and monitor the progress of treatment for depression are imperfect. Neuroimaging represents a promising avenue toward understanding the complex pathophysiologic relationships between dementia and LLD, and will support the pursuit of biomarker-driven diagnosis and treatment. Nonpharmacologic interventions to relieve depression in persons with cognitive impairment and dementia include emotion-oriented therapies, behavioral and cognitive-behavioral modification programs, and structured activity programs. Sensory-stimulation therapies and multisensory approaches show some promise for successfully treating depression in patients with dementia, but further rigorous research is needed to establish their validity. Clinical consensus and research appear to support selective serotonin reuptake inhibitors as a first choice for the pharmacological treatment of depression in patients with dementia. However, initial support for these therapies remains variable, and further investigation is needed. Extra care is required in prescribing to this population because of the generally high level of medical and psychiatric comorbidity and the potential difficulty in assessing the cognitively impaired patient's response.

Present Algorithms and Future Treatments for Alzheimer's Disease.

An estimated 47 million people live with Alzheimer's disease (AD) and other forms of dementia worldwide. Although no disease-modifying treatments are currently available for AD, earlier diagnosis and proper management of the disease could have considerable impact on patient and caregiver quality of life and functioning. Drugs currently approved for AD treat the cognitive, behavioral, and functional symptoms of the disease and consist of three cholinesterase inhibitors (ChEIs) and the N-methyl-D-aspartate receptor antagonist memantine. Treatment of patients with mild to moderate AD is generally initiated with a ChEI. Patients who show progression of symptoms while on ChEI monotherapy may be switched to another ChEI and/or memantine can be added to the treatment regimen. In recent years, putative disease-modifying therapies have emerged that aim to slow the progression of AD instead of only addressing its symptoms. However, many therapies have failed in clinical trials in patients with established AD, suggesting that, once developed, disease-modifying agents may need to be deployed earlier in the course of illness. The goal of this narrative literature review is to discuss present treatment algorithms and potential future therapies in AD.

Gender Differences in Alzheimer Disease: Brain Atrophy, Histopathology Burden, and Cognition.

Multiple studies suggest that females are affected by Alzheimer disease (AD) more severely and more frequently than males. Other studies have failed to confirm this and the issue remains controversial. Difficulties include differences in study methods and male versus female life expectancy. Another element of uncertainty is that the majority of studies have lacked neuropathological confirmation of the AD diagnosis. We compared clinical and pathological AD severity in 1028 deceased subjects with full neuropathological examinations. The age of dementia onset did not differ by gender but females were more likely to proceed to very severe clinical and pathological disease, with significantly higher proportions having a Mini-Mental State Examination score of 5 or less and Braak stage VI neurofibrillary degeneration. Median neuritic plaque densities were similar in females and males with AD but females had significantly greater tangle density scores. In addition, we found that AD-control brain weight differences were significantly greater for females, even after adjustment for age, disease duration, and comorbid conditions. These findings suggest that when they are affected by AD, females progress more often to severe cognitive dysfunction, due to more severe neurofibrillary degeneration, and greater loss of brain parenchyma.