Digital Clock and Recall is superior to the Mini-Mental State Examination for the detection of mild cognitive impairment and mild dementia.

BACKGROUND: Disease-modifying treatments for Alzheimer's disease highlight the need for early detection of cognitive decline. However, at present, most primary care providers do not perform routine cognitive testing, in part due to a lack of access to practical cognitive assessments, as well as time and resources to administer and interpret the tests. Brief and sensitive digital cognitive assessments, such as the Digital Clock and Recall (DCR™), have the potential to address this need. Here, we examine the advantages of DCR over the Mini-Mental State Examination (MMSE) in detecting mild cognitive impairment (MCI) and mild dementia. METHODS: We studied 706 participants from the multisite Bio-Hermes study (age mean ± SD = 71.5 ± 6.7; 58.9% female; years of education mean ± SD = 15.4 ± 2.7; primary language English), classified as cognitively unimpaired (CU; n = 360), mild cognitive impairment (MCI; n = 234), or probable mild Alzheimer's dementia (pAD; n = 111) based on a review of medical history with selected cognitive and imaging tests. We evaluated cognitive classifications (MCI and early dementia) based on the DCR and the MMSE against cohorts based on the results of the Rey Auditory Verbal Learning Test (RAVLT), the Trail Making Test-Part B (TMT-B), and the Functional Activities Questionnaire (FAQ). We also compared the influence of demographic variables such as race (White vs. Non-White), ethnicity (Hispanic vs. Non-Hispanic), and level of education (≥ 15 years vs. < 15 years) on the DCR and MMSE scores. RESULTS: The DCR was superior on average to the MMSE in classifying mild cognitive impairment and early dementia, AUC = 0.70 for the DCR vs. 0.63 for the MMSE. DCR administration was also significantly faster (completed in less than 3 min regardless of cognitive status and age). Among 104 individuals who were labeled as "cognitively unimpaired" by the MMSE (score ≥ 28) but actually had verbal memory impairment as confirmed by the RAVLT, the DCR identified 84 (80.7%) as impaired. Moreover, the DCR score was significantly less biased by ethnicity than the MMSE, with no significant difference in the DCR score between Hispanic and non-Hispanic individuals. CONCLUSIONS: DCR outperforms the MMSE in detecting and classifying cognitive impairment-in a fraction of the time-while being not influenced by a patient's ethnicity. The results support the utility of DCR as a sensitive and efficient cognitive assessment in primary care settings. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT04733989.

Estimating dementia risk in an African American population using the DCTclock.

The prevalence of Alzheimer's disease (AD) and related dementias (ADRD) is increasing. African Americans are twice as likely to develop dementia than other ethnic populations. Traditional cognitive screening solutions lack the sensitivity to independently identify individuals at risk for cognitive decline. The DCTclock is a 3-min AI-enabled adaptation of the well-established clock drawing test. The DCTclock can estimate dementia risk for both general cognitive impairment and the presence of AD pathology. Here we performed a retrospective analysis to assess the performance of the DCTclock to estimate future conversion to ADRD in African American participants from the Rush Alzheimer's Disease Research Center Minority Aging Research Study (MARS) and African American Clinical Core (AACORE). We assessed baseline DCTclock scores in 646 participants (baseline median age = 78.0 ± 6.4, median years of education = 14.0 ± 3.2, 78% female) and found significantly lower baseline DCTclock scores in those who received a dementia diagnosis within 3 years. We also found that 16.4% of participants with a baseline DCTclock score less than 60 were significantly more likely to develop dementia in 5 years vs. those with the highest DCTclock scores (75-100). This research demonstrates the DCTclock's ability to estimate the 5-year risk of developing dementia in an African American population. Early detection of elevated dementia risk using the DCTclock could provide patients, caregivers, and clinicians opportunities to plan and intervene early to improve cognitive health trajectories. Early detection of dementia risk can also enhance participant selection in clinical trials while reducing screening costs.

Exercise engagement drives changes in cognition and cardiorespiratory fitness after 8 weeks of aerobic training in sedentary aging adults at risk of cognitive decline.

Background: With our aging population, many individuals are at risk of developing age-related cognitive decline. Physical exercise has been demonstrated to enhance cognitive performance in aging adults. This study examined the effects of 8 weeks of aerobic exercise on cognitive performance and cardiorespiratory fitness in sedentary aging adults at risk for cognitive decline. Methods: Fifty-two participants (age 62.9 ± 6.8, 76.9% female) engaged in eight weeks of moderate-to high-intensity exercise (19 in-person, 33 remotely). Global cognition was measured by the Repeatable Battery for the Assessment of Neuropsychological Status, the Delis-Kaplan Executive Function System, and the Digit Span subtest of the Wechsler Adult Intelligence Scale (WAIS) Fourth Edition. Cardiorespiratory fitness was measured via heart rate recovery at minute 1 (HRR1) and 2 (HRR2), and exercise engagement (defined as percent of total exercise time spent in the prescribed heart rate zone). We measured pre and post changes using paired t-tests and mixed effects models, and investigated the association between cardiorespiratory and cognitive performance using multiple regression models. Cohen's d were calculated to estimate effect sizes. Results: Overall, 63.4 % of participants demonstrated high engagement (≥ 70% total exercise time spent in the prescribed heart rate zone). There were significant pre-post improvements in verbal fluency and verbal memory, and a significant decrement in working memory, but these were associated with small effect sizes (Cohen's d <0.5). Concerning cardiorespiratory fitness, there was a pre-to-post significant improvement in HRR1 (p = 0.01, d = 0.30) and HRR2 (p < 0.001, d = 0.50). Multiple regressions revealed significant associations between cardiorespiratory and cognitive performance, but all were associated with small effect sizes (Cohen's d < 0.5). Interestingly, there were significant between-group differences in exercise engagement (all p < 0.001), with remote participants demonstrating greater exercise engagement than in-person participants. Conclusion: Improvements in cognition and cardiorespiratory fitness were observed after 8 weeks of moderate to high-intensity exercise in aging adults. These results suggest that committing to a regular exercise regimen, even for a brief two-month period, can promote improvements in both cardiorespiratory fitness and cognitive performance, and that improvements are driven by exercise engagement.

Intermittent Hypoxia Differentially Regulates Adenosine Receptors in Phrenic Motor Neurons with Spinal Cord Injury.

Cervical spinal cord injury (cSCI) impairs neural drive to the respiratory muscles, causing life- threatening complications such as respiratory insufficiency and diminished airway protection. Repetitive "low dose" acute intermittent hypoxia (AIH) is a promising strategy to restore motor function in people with chronic SCI. Conversely, "high dose" chronic intermittent hypoxia (CIH; ∼8 h/night), such as experienced during sleep apnea, causes pathology. Sleep apnea, spinal ischemia, hypoxia and neuroinflammation associated with cSCI increase extracellular adenosine concentrations and activate spinal adenosine receptors which in turn constrains the functional benefits of therapeutic AIH. Adenosine 1 and 2A receptors (A1, A2A) compete to determine net cAMP signaling and likely the tAIH efficacy with chronic cSCI. Since cSCI and intermittent hypoxia may regulate adenosine receptor expression in phrenic motor neurons, we tested the hypotheses that: 1) daily AIH (28 days) downregulates A2A and upregulates A1 receptor expression; 2) CIH (28 days) upregulates A2A and downregulates A1 receptor expression; and 3) cSCI alters the impact of CIH on adenosine receptor expression. Daily AIH had no effect on either adenosine receptor in intact or injured rats. However, CIH exerted complex effects depending on injury status. Whereas CIH increased A1 receptor expression in intact (not injured) rats, it increased A2A receptor expression in spinally injured (not intact) rats. The differential impact of CIH reinforces the concept that the injured spinal cord behaves in distinct ways from intact spinal cords, and that these differences should be considered in the design of experiments and/or new treatments for chronic cSCI.

Daily acute intermittent hypoxia enhances serotonergic innervation of hypoglossal motor nuclei in rats with and without cervical spinal injury.

Intermittent hypoxia elicits protocol-dependent effects on hypoglossal (XII) motor plasticity. Whereas low-dose, acute intermittent hypoxia (AIH) elicits serotonin-dependent plasticity in XII motor neurons, high-dose, chronic intermittent hypoxia (CIH) elicits neuroinflammation that undermines AIH-induced plasticity. Preconditioning with repeated AIH and mild CIH enhance AIH-induced XII motor plasticity. Since intermittent hypoxia pre-conditioning could enhance serotonin-dependent XII motor plasticity by increasing serotonergic innervation density of the XII motor nuclei, we tested the hypothesis that 3 distinct intermittent hypoxia protocols commonly studied to elicit plasticity (AIH) or simulate aspects of sleep apnea (CIH) differentially affect XII serotonergic innervation. Sleep apnea and associated CIH are common in people with cervical spinal injuries and, since repetitive AIH is emerging as a promising therapeutic strategy to improve respiratory and non-respiratory motor function after spinal injury, we also tested the hypotheses that XII serotonergic innervation is increased by repetitive AIH and/or CIH in rats with cervical C2 hemisections (C2Hx). Serotonergic innervation was assessed via immunofluorescence in male Sprague Dawley rats, with and without C2Hx (beginning 8 weeks post-injury) exposed to 28 days of: 1) normoxia; 2) daily AIH (10, 5-min 10.5% O2 episodes per day; 5-min normoxic intervals); 3) mild CIH (5-min 10.5% O2 episodes; 5-min intervals; 8 h/day); and 4) moderate CIH (2-min 10.5% O2 episodes; 2-min intervals; 8 h/day). Daily AIH, but neither CIH protocol, increased the area of serotonergic immunolabeling in the XII motor nuclei in both intact and injured rats. C2Hx per se had no effect on XII serotonergic innervation density. Thus, daily AIH may increases XII serotonergic innervation and function, enhancing the capacity for serotonin-dependent, AIH-induced plasticity in upper airway motor neurons. Such effects may preserve upper airway patency and/or swallowing ability in people with cervical spinal cord injuries and other clinical disorders that compromise breathing and airway defense.

Adulthood systemic inflammation accelerates the trajectory of age-related cognitive decline.

In order to understand the long-term effects of systemic inflammation, it is important to distinguish inflammation-induced changes in baseline cognitive function from changes that interact with aging to influence the trajectory of cognitive decline. Lipopolysaccharide (LPS; 1 mg/kg) or vehicle was administered to young adult (6 months) male rats via intraperitoneal injections, once a week for 7 weeks. Longitudinal effects on cognitive decline were examined 6 and 12 months after the initial injections. Repeated LPS treatment, in adults, resulted in a long-term impairment in memory, examined in aged animals (age 18 months), but not in middle-age (age 12 months). At 12 months following injections, LPS treatment was associated with a decrease in N-methyl-D-aspartate receptor-mediated component of synaptic transmission and altered expression of genes linked to the synapse and to regulation of the response to inflammatory signals. The results of the current study suggest that the history of systemic inflammation is one component of environmental factors that contribute to the resilience or susceptibility to age-related brain changes and associated trajectory of cognitive decline.

Phrenic motor neuron survival below cervical spinal cord hemisection.

Cervical spinal cord injury (cSCI) severs bulbospinal projections to respiratory motor neurons, paralyzing respiratory muscles below the injury. C2 spinal hemisection (C2Hx) is a model of cSCI often used to study spontaneous and induced plasticity and breathing recovery post-injury. One key assumption is that C2Hx dennervates motor neurons below the injury, but does not affect their survival. However, a recent study reported substantial bilateral motor neuron death caudal to C2Hx. Since phrenic motor neuron (PMN) death following C2Hx would have profound implications for therapeutic strategies designed to target spared neural circuits, we tested the hypothesis that C2Hx minimally impacts PMN survival. Using improved retrograde tracing methods, we observed no loss of PMNs at 2- or 8-weeks post-C2Hx. We also observed no injury-related differences in ChAT or NeuN immunolabeling within labelled PMNs. Although we found no evidence of PMN loss following C2Hx, we cannot rule out neuronal loss in other motor pools. These findings address an essential prerequisite for studies that utilize C2Hx as a model to explore strategies for inducing plasticity and/or regeneration within the phrenic motor system, as they provide important insights into the viability of phrenic motor neurons as therapeutic targets after high cervical injury.

Protocol-Specific Effects of Intermittent Hypoxia Pre-Conditioning on Phrenic Motor Plasticity in Rats with Chronic Cervical Spinal Cord Injury.

"Low-dose" acute intermittent hypoxia (AIH; 3-15 episodes/day) is emerging as a promising therapeutic strategy to improve motor function after incomplete cervical spinal cord injury (cSCI). Conversely, chronic "high-dose" intermittent hypoxia (CIH; > 80-100 episodes/day) elicits multi-system pathology and is a hallmark of sleep apnea, a condition highly prevalent in individuals with cSCI. Whereas daily AIH (dAIH) enhances phrenic motor plasticity in intact rats, it is abolished by CIH. However, there have been no direct comparisons of prolonged dAIH versus CIH on phrenic motor outcomes after chronic cSCI. Thus, phrenic nerve activity and AIH-induced phrenic long-term facilitation (pLTF) were assessed in anesthetized rats. Experimental groups included: 1) intact rats exposed to 28 days of normoxia (Nx28; 21% O2; 8 h/day), and three groups with chronic C2 hemisection (C2Hx) exposed to either: 2) Nx28; 3) dAIH (dAIH28; 10, 5-min episodes of 10.5% O2/day; 5-min intervals); or 4) CIH (IH28-2/2; 2-min episodes; 2-min intervals; 8 h/day). Baseline ipsilateral phrenic nerve activity was reduced in injured versus intact rats but unaffected by dAIH28 or IH28-2/2. There were no group differences in contralateral phrenic activity. pLTF was enhanced bilaterally by dAIH28 versus Nx28 but unaffected by IH28-2/2. Whereas dAIH28 enhanced pLTF after cSCI, it did not improve baseline phrenic output. In contrast, unlike shorter protocols in intact rats, CIH28-2/2 did not abolish pLTF in chronic C2Hx. Mechanisms of differential responses to dAIH versus CIH are not yet known, particularly in the context of cSCI. Further, it remains unclear whether enhanced phrenic motor plasticity can improve breathing after cSCI.

Serotonergic innervation of respiratory motor nuclei after cervical spinal injury: Impact of intermittent hypoxia.

Although cervical spinal cord injury (cSCI) disrupts bulbo-spinal serotonergic projections, partial recovery of spinal serotonergic innervation below the injury site is observed after incomplete cSCI. Since serotonin contributes to functional recovery post-injury, treatments to restore or accelerate serotonergic reinnervation are of considerable interest. Intermittent hypoxia (IH) was reported to increase serotonin innervation near respiratory motor neurons in spinal intact rats, and to improve function after cSCI. Here, we tested the hypotheses that spontaneous serotonergic reinnervation of key respiratory (phrenic and intercostal) motor nuclei: 1) is partially restored 12 weeks post C2 hemisection (C2Hx); 2) is enhanced by IH; and 3) results from sprouting of spared crossed-spinal serotonergic projections below the site of injury. Serotonin was assessed via immunofluorescence in male Sprague Dawley rats with and without C2Hx (12 wks post-injury); individual groups were exposed to 28 days of: 1) normoxia; 2) daily acute IH (dAIH28: 10, 5 min 10.5% O2 episodes per day; 5 min normoxic intervals); 3) mild chronic IH (IH28-5/5: 5 min 10.5% O2 episodes; 5 min intervals; 8 h/day); or 4) moderate chronic IH (IH28-2/2: 2 min 10.5% O2 episodes; 2 min intervals; 8 h/day), simulating IH experienced during moderate sleep apnea. After C2Hx, the number of ipsilateral serotonergic structures was decreased in both motor nuclei, regardless of IH protocol. However, serotonergic structures were larger after C2Hx in both motor nuclei, and total serotonin immunolabeling area was increased in the phrenic motor nucleus but reduced in the intercostal motor nucleus. Both chronic IH protocols increased serotonin structure size and total area in the phrenic motor nuclei of uninjured rats, but had no detectable effects after C2Hx. Although the functional implications of fewer but larger serotonergic structures are unclear, we confirm that serotonergic reinnervation is substantial following injury, but IH does not affect the extent of reinnervation.

Structural fingerprints and their evolution during oligomeric vs. oligomer-free amyloid fibril growth.

Deposits of fibrils formed by disease-specific proteins are the molecular hallmark of such diverse human disorders as Alzheimer's disease, type II diabetes, or rheumatoid arthritis. Amyloid fibril formation by structurally and functionally unrelated proteins exhibits many generic characteristics, most prominently the cross ß-sheet structure of their mature fibrils. At the same time, amyloid formation tends to proceed along one of two separate assembly pathways yielding either stiff monomeric filaments or globular oligomers and curvilinear protofibrils. Given the focus on oligomers as major toxic species, the very existence of an oligomer-free assembly pathway is significant. Little is known, though, about the structure of the various intermediates emerging along different pathways and whether the pathways converge towards a common or distinct fibril structures. Using infrared spectroscopy we probed the structural evolution of intermediates and late-stage fibrils formed during in vitro lysozyme amyloid assembly along an oligomeric and oligomer-free pathway. Infrared spectroscopy confirmed that both pathways produced amyloid-specific ß-sheet peaks, but at pathway-specific wavenumbers. We further found that the amyloid-specific dye thioflavin T responded to all intermediates along either pathway. The relative amplitudes of thioflavin T fluorescence responses displayed pathway-specific differences and could be utilized for monitoring the structural evolution of intermediates. Pathway-specific structural features obtained from infrared spectroscopy and Thioflavin T responses were identical for fibrils grown at highly acidic or at physiological pH values and showed no discernible effects of protein hydrolysis. Our results suggest that late-stage fibrils formed along either pathway are amyloidogenic in nature, but have distinguishable structural fingerprints. These pathway-specific fingerprints emerge during the earliest aggregation events and persist throughout the entire cascade of aggregation intermediates formed along each pathway.

Epigonal conditioned media from bonnethead shark, Sphyrna tiburo, induces apoptosis in a T-cell leukemia cell line, Jurkat E6-1.

Representatives of Subclass Elasmobranchii are cartilaginous fish whose members include sharks, skates, and rays. Because of their unique phylogenetic position of being the most primitive group of vertebrates to possess all the components necessary for an adaptive immune system, the immune regulatory compounds they possess may represent the earliest evolutionary forms of novel compounds with the potential for innovative therapeutic applications. Conditioned medium, generated from short term culture of cells from the epigonal organ of bonnethead sharks (Sphyrna tiburo), has been shown to have potent reproducible cytotoxic activity against a variety of human tumor cell lines in vitro. Existing data suggest that epigonal conditioned medium (ECM) exerts this cytotoxic activity through induction of apoptosis in target cells. This manuscript describes apoptosis induction in a representative tumor cell line, Jurkat E6-1, in response to treatment with ECM at concentrations of 1 and 2 mg/mL. Data indicate that ECM exposure initiates the mitochondrial pathway of apoptosis through activation of caspase enzymes. Future purification of ECM components may result in the isolation of an immune-regulatory compound with potential therapeutic benefit for treatment of human cancer.