Sleep spindle architecture associated with distinct clinical phenotypes in older adults at risk for dementia.

Sleep spindles are a hallmark of non-REM sleep and play a fundamental role in memory consolidation. Alterations in these spindles are emerging as sensitive biomarkers for neurodegenerative diseases of ageing. Understanding the clinical presentations associated with spindle alterations may help to elucidate the functional role of these distinct electroencephalographic oscillations and the pathophysiology of sleep and neurodegenerative disorders. Here, we use a data-driven approach to examine the sleep, memory and default mode network connectivity phenotypes associated with sleep spindle architecture in older adults (mean age = 66 years). Participants were recruited from a specialist clinic for early diagnosis and intervention for cognitive decline, with a proportion showing mild cognitive deficits on neuropsychological testing. In a sample of 88 people who underwent memory assessment, overnight polysomnography and resting-state fMRI, a k-means cluster analysis was applied to spindle measures of interest: fast spindle density, spindle duration and spindle amplitude. This resulted in three clusters, characterised by preserved spindle architecture with higher fast spindle density and longer spindle duration (Cluster 1), and alterations in spindle architecture (Clusters 2 and 3). These clusters were further characterised by reduced memory (Clusters 2 and 3) and nocturnal hypoxemia, associated with sleep apnea (Cluster 3). Resting-state fMRI analysis confirmed that default mode connectivity was related to spindle architecture, although directionality of this relationship differed across the cluster groups. Together, these results confirm a diversity in spindle architecture in older adults, associated with clinically meaningful phenotypes, including memory function and sleep apnea. They suggest that resting-state default mode connectivity during the awake state can be associated with sleep spindle architecture; however, this is highly dependent on clinical phenotype. Establishing relationships between clinical and neuroimaging features and sleep spindle alterations will advance our understanding of the bidirectional relationships between sleep changes and neurodegenerative diseases of ageing.

Anterolateral knee complex considerations in contemporary anterior cruciate ligament reconstruction and total knee arthroplasty: a systematic review.

The anterolateral ligament (ALL) was first described in 1879 in the context of Segond fractures, which correlate with a 75-100% chance of an anterior cruciate ligament (ACL) tear or a 66-75% chance of a meniscal tear. The purpose of this paper is to provide an updated comprehensive review on the anterolateral ligament complex of the knee focusing on the: (1) anatomy of the ALL/ALC; (2) associated biomechanics/function; and (3) important surgical considerations in contemporary anterior cruciate ligament (ACL) reconstruction and total knee arthroplasty (TKA). A systematic review of studies on ALL was conducted on Pubmed/MEDLINE and Cochrane databases (May 7th, 2020 to February 1st, 2022), with 20 studies meeting inclusion/exclusion criteria. Studies meeting inclusion criteria were anatomical/biomechanical studies assessing ALL function, cadaveric and computer simulations, and comparative studies on surgical outcomes of ALLR (concomitant with ACL reconstruction). Eight studies were included and graded by MINOR and Newcastle-Ottawa scale to identify potential biases. The anatomy of the ALL is part of the anterolateral ligament complex (ALC), which includes the superficial/deep iliotibial band (including the Kaplan fiber system), iliopatellar band, ALL, and anterolateral capsule. Multiple biomechanical studies have characterized the ALC as a secondary passive stabilizer in resisting tibial internal rotation. Given the role of the ALC in resisting internal tibial rotation, lateral extra-articular procedures including ALL augmentation may be considered for chronic ACL tears, ACL revisions, and a high-grade pivot shift test. In the context of TKA, in the event of injury to the ALC, a more constrained implant or soft-tissue reconstruction may be necessary to restore appropriate knee stability.

Surgical Trends for Managing Knee Osteonecrosis: A 2010 to 2020 United States Nationwide Study.

BACKGROUND: Knee osteonecrosis (ON) is rare, with an estimated incidence of 0.01-0.17 per 1,000 person years. Our study aimed to do the following: 1) quantify total operative procedures with rates normalized to the United States population; 2) compare arthroplasty versus joint-preserving procedural trends; and 3) determine rates of specific operative techniques/demographics in patients aged <50 versus >50 years. METHODS: Using a nationwide database, 8,269 patients diagnosed with knee ON underwent surgical treatment from 2010 to 2020. Documented surgical procedures included total knee arthroplasty (TKA), unicompartmental knee arthroplasty (UKA), and core decompression. Primary outcomes included procedural utilization with subanalyses comparing arthroplasty versus joint-preserving procedures, and age-stratified by under/over 50 years. Linear regressions were evaluated for trends in procedural volumes over time. RESULTS: From 2010 to 2014, 0.54% of all knee procedures were to treat ON compared to 0.71% from 2015 to 2020 (P < .001). Overall rates of TKA (85.4%) and UKA (10.3%) far exceeded rates of joint preserving procedures (4.3%). Comparing 2010-2014 with 2015-2019, joint-preserving procedures proportionally increased (0.7 to 5.0%, P < .001). Patients <50 years had significantly more joint-preserving procedures (19.5 versus 2.7%). Overall, TKA was the most common procedure (7,062; 85.40%), following by UKA 853; 10.32%) and core decompression (354; 4.28%). CONCLUSION: To our knowledge, this is the first study to characterize surgical trends in management of knee ON. Overall surgical volume for knee ON has continued to increase, outpacing population growth. Patients who have knee ON are most commonly managed with arthroplasty procedures, specifically TKA. Younger aged patients (<50 years) are more likely to undergo joint-preserving procedures, namely core decompression.

What are the Causes, Costs and Risk-Factors for Emergency Department Visits Following Primary Total Hip Arthroplasty? An Analysis of 1,018,772 Patients.

BACKGROUND: Well-powered studies analyzing the relationship and nature of emergency department (ED) visits following primary total hip arthroplasties (THAs) are limited. The aim of this study was to: 1) compare baseline demographics of patients with/without an ED visit; 2) determine leading causes of ED visits; 3) identify patient-related risk factors; and 4) quantify 90-day episode-of-care healthcare costs divided by final diagnosis. METHODS: Patients undergoing primary THA between January 1, 2010 and October 1, 2020 who presented to the ED within 90-days postoperatively were identified using the Mariner dataset of PearlDiver, yielding 1,018,772 patients. This included 3.9% (n = 39,439) patients who did and 96.1% (n = 979,333) who did not have an ED visit. Baseline demographics between the control/study cohorts, ED visit causes, risk-factors, and subsequent costs-of-care were analyzed. Using Bonferroni-correction, a P-value less than 0.002 was considered statistically significant. RESULTS: Patients who presented to the ED post-operatively were most often aged 65-74 years old (41.09%) or female sex (55.60%). Nonmusculoskeletal etiologies comprised 66.8% of all ED visits. Risk factors associated with increased ED visits included alcohol abuse, depressive disorders, congestive heart failure, coagulopathy, and electrolyte/fluid derangements (P < .001 for all). Pulmonary ($28,928.01) and cardiac ($28,574.69) visits attributed to the highest costs of care. CONCLUSION: Nonmusculoskeletal causes constituted the majority of ED visits. The top five risk factors associated with increased odds of ED visits were alcohol abuse, electrolyte/fluid derangements, congestive heart failure, coagulopathy, and depression. This study highlights potential areas of pre-operative medical optimization that may reduce ED visits following primary THA.

Comparison of patient demographics, utilization trends, and costs of total ankle arthroplasty and ankle fusion in the United States from 2010 to 2019.

INTRODUCTION: Contemporary studies evaluating utilization and trends of total ankle arthroplasty (TAA) and ankle fusion (AF) for tibiotalar osteoarthritis are sparse. Therefore, the purpose of this study was to utilize a nationwide administrative claims database from 2010 to 2019 to compare: (1) baseline demographics; (2) utilization, (3) in-hospital length of stay (LOS), and (4) costs of care. METHODS: Using the PearlDiver database, a retrospective query from January 1st, 2010 to December 31st, 2019 was performed for all patients who underwent TAA and AF for tibiotalar osteoarthritis. Baseline demographics, comorbidities, and geographic utilization were compared using Pearson Chi-square analyses. Linear regression was used to compare differences in procedure utilization and in-hospital LOS during the study interval. Reimbursements between the two cohorts during the study interval were compared. A p value less than 0.05 was statistically significant. RESULTS: In total, 14,248 patients underwent primary TAA (n = 5544) or AF (n = 8704). Patients undergoing AF were generally younger (< 60) with greater comorbidity burden driven by hypertension, diabetes mellitus, obesity, and tobacco use compared to TAA patients (p < 0.0001). Over the study interval, TAA utilization remained constant (912 vs 909 procedures; p = 0.807), whereas AF utilization decreased by 42.5% (1737 vs 998 procedures; p = 0.0001). Mean in-hospital LOS for patients undergoing TAA decreased (2.5 days vs. 2.0 days, p = 0.0004), while AF LOS increased (2.6 days vs. 3.5 days, p = 0.0003). Reimbursements for both procedures significantly declined over the study interval (TAA: $4559-$2156, AF: $4729-$1721; p < 0.013). CONCLUSION: TAA utilization remained constant, while AF utilization declined by 42.5% from 2010 to 2019. There was divergence in the LOS for TAA versus AF patients. Both procedures significantly declined by over 50% in reimbursements over the study interval.

Sleep-Dependent Memory in Older People With and Without MCI: The Relevance of Sleep Microarchitecture, OSA, Hippocampal Subfields, and Episodic Memory.

This study aimed to determine if, relative to cognitively healthy controls, sleep-dependent memory consolidation (SDMC) is diminished in mild cognitive impairment (MCI), a group at high risk of conversion to dementia. We also sought to determine whether SDMC is associated with sleep characteristics, daytime episodic memory, and hippocampal integrity. Participants with MCI (n = 43) and controls (n = 20) underwent clinical and neuropsychological profiling. From polysomnography, apnea hypopnea index (AHI) and non-REM sleep spindle characteristics were derived. From magnetic resonance imaging, hippocampal subfield volumes were computed. Participants learned a novel 32-item word-pair prior to sleep; morning retention of the word-pairs was used to determine SDMC. Results showed that SDMC did not differ between MCI and controls, but there was a large effect size decrement in SDMC in those with multiple domain MCI (Hedge's g = 0.85). In MCI, poorer SDMC was correlated with CA1 and CA3 hippocampal atrophy, shorter spindle duration, and worse daytime episodic memory. In controls, poorer SDMC was associated with higher AHI. Impaired daytime memory consolidation, reduced hippocampal volumes, shorter sleep spindles, and greater sleep apnea severity are indicators of diminished SDMC in older adults and should be explored in future studies.

Comparison study of patient demographics and risk factors for infections following primary total hip arthroplasty for femoral neck fractures.

INTRODUCTION: While studies have shown favorable outcomes in the treatment of femoral neck fractures with the utilization of total hip arthroplasty (THA), adverse events, such as infections, can still occur. Therefore, the aims of this study were to 1) compare baseline demographics and 2) identify risk factors associated with developing either surgical site infections (SSIs) or peri-prosthetic joint infections (PJIs). MATERIALS AND METHODS: A retrospective analysis of patients who underwent primary THA for femoral neck fractures were queried from the Medicare database. The inclusion criteria consisted of patients developing SSIs within 90 days or PJIs within 3 years following the index procedure. The query yielded 2502 patients who developed infections in the form of either SSIs (n = 987) or PJIs (n = 1515) out of 57,191 patients treated for femoral neck fractures with primary THA. Primary endpoints were to compare baseline demographic profiles and determine risk factors associated with developing infections. Multivariate binomial logistic regression analyses were performed to determine the odds (OR) of developing infections. A p value less than 0.001 was considered to be statistically significant. RESULTS: Patients who developed either infections were found to be significantly different when compared to patients who did not develop infections. SSI (10 vs. 8, p < 0.0001) and PJI (9 vs. 5, p < 0.0001) patients both had significantly higher mean Elixhauser Comorbidity Index (ECI) scores compared to their counterparts. The regression model found the greatest risks for developing SSIs included hypertension (OR 1.63, p = 0.001), pathologic weight loss (OR 1.58, p < 0.0001), and iron deficiency anemia (IDA) (OR 1.48, p < 0.0001), whereas IDA (OR 2.14, p < 0.0001), pathologic weight loss (OR 1.75, p < 0.0001), and rheumatoid arthritis (OR 1.57, p < 0.0001) increased the odds for PJIs. CONCLUSION: This study can be utilized by orthopedic surgeons and other healthcare professionals to adequately educate these patients of the complications which may occur following their surgery.

Crohn's Disease is Associated with Longer In-Hospital Lengths of Stay and Higher Rates of Complications and Costs after Primary Total Hip Arthroplasty.

BACKGROUND: As the incidence and prevalence of Crohn's disease continues to change worldwide, rates within North America have been increasing. The objective of this study was to evaluate whether patients who have Crohn's disease undergoing primary total hip arthroplasties have worse outcomes compared with matched cohorts. Specifically, we evaluated 1) medical complications, 2) in-hospital lengths of stay (LOS), and 3) costs of care. METHODS: Two cohorts of patients who underwent primary total hip arthroplasties from January 1, 2005 to March 31, 2014 were identified from the Medicare claims of the PearlDiver platform. Cohorts were matched by age, sex, and following comorbidities-anemia, diabetes, hyperlipidemia, hypertension, malnutrition, pulmonary disease, and renal failure, yielding 55,361 patients within the study (n = 9229) and matching cohorts (n = 46,132). Outcomes assessed included 90-day medical complications, in-hospital LOS, and costs of care. A P-value less than .005 was considered statistically significant. RESULTS: Patients with Crohn's disease were found to have significantly higher incidences and odds ratios of 90-day medical complications (30.2 vs 13.8; odds ratios: 2.2, P < .0001). They were also found to have significantly longer LOS (3.8- vs 3.6-days, P < .0001) and higher day of surgery ($12,662.00 vs 12,271.15, P < .0001) and 90-day episode costs ($16,933.18 vs $15,670.32, P < .0001). CONCLUSION: Crohn's disease is associated with higher rates of medical complications, longer in-hospital LOS, and increased costs of care. This study may aid physicians to perform appropriate risk adjustment for adverse outcomes and to educate these patients about potential postoperative complications in these patients.

Interplay of Nitrogen-Atom Inversion and Conformational Inversion in Enantiomerization of 1H-1-Benzazepines.

A series of 2,4-disubstituted 1H-1-benzazepines, 2a-d, 4, and 6, were studied, varying both the substituents at C2 and C4 and at the nitrogen atom. The conformational inversion (ring-flip) and nitrogen-atom inversion (N-inversion) energetics were studied by variable-temperature NMR spectroscopy and computations. The steric bulk of the nitrogen-atom substituent was found to affect both the conformation of the azepine ring and the geometry around the nitrogen atom. Also affected were the Gibbs free energy barriers for the ring-flip and the N-inversion. When the nitrogen-atom substituent was alkyl, as in 2a-c, the geometry of the nitrogen atom was nearly planar and the azepine ring was highly puckered; the result was a relatively high-energy barrier to ring-flip and a low barrier to N-inversion. Conversely, when the nitrogen-atom substituent was a hydrogen atom, as in 2d, 4, and 6, the nitrogen atom was significantly pyramidalized and the azepine ring was less puckered; the result here was a relatively high energy barrier to N-inversion and a low barrier to ring-flip. In these N-unsubstituted compounds, it was found computationally that the lowest-energy stereodynamic process was ring-flip coupled with N-inversion, as N-inversion alone had a much higher energy barrier.

Cyclophilin D extramitochondrial signaling controls cell cycle progression and chemokine-directed cell motility.

Mitochondria control bioenergetics and cell fate decisions, but how they influence nuclear gene expression is understood poorly. Here, we show that deletion or reduction in the levels of cyclophilin D (CypD, also called Ppif), a mitochondrial matrix peptidyl prolyl isomerase and apoptosis regulator, results in increased cell proliferation and enhanced cell migration and invasion. These responses are associated with extensive transcriptional changes, modulation of a chemokine/chemokine receptor gene signature, and activation of the pleiotropic inflammatory mediator, STAT3. In the absence of CypD, active STAT3 enhances cell proliferation via accelerated entry into S-phase and stimulates autocrine/paracrine cell motility through Cxcl12-Cxcr4-directed chemotaxis. Therefore, CypD directs mitochondria-to-nuclei inflammatory gene expression in normal and tumor cells. This pathway may contribute to malignant traits under conditions of CypD modulation.

A New Role for Chatbots: Automation of a Sleep-Dependent Memory Task.

Sleep is known to contribute to memory consolidation. Sleep-dependent memory is not often studied in patients with mild cognitive impairment (MCI), however, due to the need to attend sleep laboratories which are typically expensive, time-consuming and lacking in trained task administrators. We developed a conversation agent able to deliver a sleep-dependent memory task at home. Utility of the chatbot was confirmed through in-house testing and focus groups. The chatbot promises consistent task delivery and improved access for people with MCI.

Recent advances in understanding of sleep disorders and disturbances for dementia risk and prevention.

PURPOSE OF REVIEW: To synthesise the recent work examining the relationship between sleep disturbances and dementia, emphasising studies involving individuals with mild cognitive impairment (MCI) or Alzheimer's disease (AD) and/or those investigating AD biomarkers. Additionally, we provide an update on recent interventions targeting sleep-related issues in older adults with MCI or AD. RECENT FINDINGS: Various studies have examined obstructive sleep apnoea, sleep duration, and circadian alterations in relation to Alzheimer's pathology and dementia risk, with an emerging body of evidence suggesting that cardiovascular disease, hypertension, glymphatic function, and inflammation might serve as plausible pathophysiological mechanisms contributing to dementia during critical brain periods. Conversely, recent studies investigating insomnia have produced disparate results. Regarding intervention studies, the scarcity of prospective randomised control trials poses a challenge in establishing the benefits of addressing sleep disorders and disturbances. SUMMARY: Recent work examining the pathophysiological links between sleep and dementia is strongest for obstructive sleep apnoea and sleep duration, while findings in insomnia studies exhibit inconsistency, possibly due to varied associations with dementia among different insomnia subtypes. It is apparent that more longitudinal studies examining the underlying pathophysiological mechanisms are necessary, alongside more rigorous clinical trials. Although some trials are underway in this field, there is still scarcity in trials examining interventions for circadian disturbances.

Depressive Disorder and Trimalleolar Fractures: An Analysis of Outcomes and Costs.

INTRODUCTION: Studies have suggested a strong association between depression and poor outcomes following various orthopaedic surgeries. However, depression's impact on complications following open reduction/internal fixation (ORIF) of trimalleolar fractures has not been elucidated. Therefore, this study aimed to determine whether depression is associated with higher rates of readmissions and medical complications following ORIF of trimalleolar fractures. METHODS: A database query from January, 2020, through March, 2021, identifying adults who underwent trimalleolar ORIF generated 50 154 patients. Those with depression were matched 1:1 to controls without depression by age, sex, chronic obstructive pulmonary disease, anxiety, and other prominent comorbidities. Primary endpoints compared 90-day all-cause readmissions and medical complications. Odds ratios (ORs) of the effect of depression on readmissions and medical complications were calculated. RESULTS: Patients with depression who underwent ORIF of trimalleolar fractures had significantly higher odds of being readmitted within 90 days of the initial procedure (OR: 1.37; P < .0001). Ninety-day odds of developing medical complications were significantly higher (OR: 4.61; P < .0001) in patients with depression compared with patients within the control group. CONCLUSION: Patients with depression undergoing trimalleolar ORIF face an increased risk of readmission and multiple postoperative complications. Orthopaedic surgeons should factor depression into their preoperative evaluation, given the already high burden of complications following ORIF of trimalleolar fractures. LEVEL OF EVIDENCE: Level III: Retrospective cohort study.

Risk Factors for Undergoing Surgical Intervention for Vertebral Compression Fractures: An Analysis of 703,499 Patients.

BACKGROUND: Vertebral compression fractures (VCFs) are typically treated nonoperatively but can be treated with either kyphoplasty or vertebroplasty when indicated. The decision to treat patients with/without surgical intervention is dependent on the severity of deformity and patient risk profile. The aims of this study were to: 1) compare baseline patient demographics, 2) identify risk factors of patients undergoing operative vs. nonoperative management, and 3) identify patient-specific risk factors associated with postoperative readmissions. METHODS: This retrospective database study used patient information from January 1st, 2010, to October 31st, 2021. Cohorts were identified by patients diagnosed with VCFs through International Classification of Disease, Ninth Revision (ICD-9), ICD-10 codes, identifying those undergoing kyphoplasty/vertebroplasty via Current Procedural Terminology codes. The 2 research domains utilized in this investigation were baseline demographic profiles of patients who underwent kyphoplasty or vertebroplasty for treatment of VCFs, and those who underwent nonoperative management served as the control cohort. RESULTS: Of the 703,499 patients diagnosed with VCFs, 76,126 patients (10.8%) underwent kyphoplasty or vertebroplasty within 90 days of diagnosis of a VCF. Univariate analysis demonstrated female sex was associated with increased risk of undergoing surgical management for VCF (P < 0.0001). Several comorbidities were significantly associated with increased rates of readmission including hypertension, tobacco use, coronary artery disease, and chronic obstructive pulmonary disease (P < 0.0001 for all). CONCLUSIONS: This study highlights specific comorbidities that are significantly associated with higher rates of kyphoplasty or vertebroplasty for the treatment of thoracolumbar wedge compression fractures and increased risk for 90-day postoperative hospital readmission.

Novel Dual Bicolumnar Fibula Graft Reconstruction of Distal Humerus in Pediatric Patients After Massive Bone Resection: A Report of Two Cases.

CASE: We describe 2 case studies, involving a 10-year-old girl with an aneurysmal bone cyst and a 12-year-old adolescent boy with Ewing sarcoma. The patient with Ewing sarcoma was previously managed with wide surgical excision and fibular graft reconstruction and subsequently experienced significant graft resorption, hardware failure, and fracture 24 months after operation. A revision limb salvage attempt was undertaken. In both cases, fibular strut grafts were harvested and fixed with intramedullary k-wires to recreate the medial and lateral columns of the distal humeral triangle. CONCLUSION: The technique achieved complete osseous integration, structural support, and functional restoration of the elbow in both cases, with good functional outcomes.

Operative Time Associated With Increased Length of Stay After Single-level Cervical Disk Arthroplasty: An Analysis of 3681 Surgeries.

STUDY DESIGN: Level III evidence-retrospective cohort. OBJECTIVE: The purpose of this study was to (1) determine whether longer CDA operative time increases the risk of 30-day postoperative complications, (2) analyze the association between operative time and subsequent health care utilization, and (3) discharge disposition. BACKGROUND: Cervical disk arthroplasty (CDA) most commonly serves as an alternative to anterior cervical discectomy and fusion (ACDF) to treat cervical spine disease, however, with only 1600 CDAs performed annually relative to 132,000 ACDFs, it is a relatively novel procedure. METHODS: A retrospective query was performed identifying patients who underwent single-level CDA between January 2012 and December 2018 using a nationwide database. Differences in baseline patient demographics were identified through univariate analysis. Multivariate logistic regression was performed to identify associations between operative time (reference: 81-100 min), medical/surgical complications, and health care utilization. RESULTS: A total of 3681 cases were performed, with a mean patient age of 45.52 years and operative time of 107.72±49.6 minutes. Higher odds of length of stay were demonstrated starting with operative time category 101-120 minutes (odds ratio: 2.164, 95% CI: 1.247-3.754, P=0.006); however, not among discharge destination, 30-day unplanned readmission, or reoperation. Operative time <40 minutes was associated with 10.7x odds of nonhome discharge, while >240 minutes was associated with 4.4 times higher odds of LOS>2 days (P<0.01). Increased operative time was not associated with higher odds of wound complication/infection, pulmonary embolism, deep venous thrombosis, or urinary tract infections. CONCLUSIONS: Prolonged CDA operative time above the reference 81-100 minutes is independently associated with increased length of stay, but not other significant health care utilization parameters, including discharge disposition, readmission, or reoperation. There was no association between prolonged operative time and 30-day medical/surgical complications, including wound complications, infections, pulmonary embolism, or urinary tract infection.

Electroencephalographic slowing during REM sleep in older adults with subjective cognitive impairment and mild cognitive impairment.

STUDY OBJECTIVES: In older adults with Alzheimer's disease, slowing of electroencephalographic (EEG) activity during REM sleep has been observed. Few studies have examined EEG slowing during REM in those with mild cognitive impairment (MCI) and none have examined its relationship with cognition in this at-risk population. METHODS: Two hundred and ten older adults (mean age = 67.0, SD = 8.2 years) underwent comprehensive neuropsychological, medical, and psychiatric assessment and overnight polysomnography. Participants were classified as subjective cognitive impairment (SCI; n = 75), non-amnestic MCI (naMCI, n = 85), and amnestic MCI (aMCI, n = 50). REM EEG slowing was defined as (δ + θ)/(α + σ + ß) power and calculated for frontal, central, parietal, and occipital regions. Analysis of variance compared REM EEG slowing between groups. Correlations between REM EEG slowing and cognition, including learning and memory, visuospatial and executive functions, were examined within each subgroup. RESULTS: The aMCI group had significantly greater REM EEG slowing in the parietal and occipital regions compared to the naMCI and SCI groups (partial η2 = 0.06, p < 0.05 and 0.06, p < 0.05, respectively), and greater EEG slowing in the central region compared to SCI group (partial η2 = 0.03, p < 0.05). Greater REM EEG slowing in parietal (r = -0.49) and occipital regions (r = -0.38 [O1/M2] and -0.33 [O2/M1]) were associated with poorer visuospatial performance in naMCI. CONCLUSIONS: REM EEG slowing may differentiate older adults with memory impairment from those without. Longitudinal studies are now warranted to examine the prognostic utility of REM EEG slowing for cognitive and dementia trajectories.

Assessing sleep architecture and cognition in older adults with depressive symptoms attending a memory clinic.

BACKGROUND: While depression is intrinsically and bidirectionally linked with both sleep disturbance and cognition, the inter-relationships between sleep, cognition, and brain integrity in older people with depression, especially those with late-onset depression are undefined. METHODS: One hundred and seventy-two older adults (mean age 64.3 ± 6.9 years, Depression: n = 66, Control: n = 106) attending a memory clinic underwent a neuropsychological battery of declarative memory, executive function tasks, cerebral magnetic resonance imaging and overnight polysomnography with quantitative electroencephalography. RESULTS: The time spent in slow-wave sleep (SWS) and rapid eye movement (REM) sleep, slow-wave activity, sleep spindles, hippocampal volume and prefrontal cortex thickness did not differ between depression and control and depression onset groups. However, sleep onset latency (p = 0.005) and REM onset latency (p = 0.02) were later in the Depression group compared to controls. Less SWS was associated with poorer memory (r = 0.31, p = 0.023) in the depression group, and less SWS was related to better memory in the control group (r = -0.20, p = 0.043; Fishers r-to-z = -3.19). LIMITATIONS: Longitudinal studies are needed to determine if changes in sleep in those with depressive symptoms predict cognitive decline and illness trajectory. CONCLUSION: Older participants with depressive symptoms had delayed sleep initiation, suggestive of delayed sleep phase. The association between SWS and memory suggests SWS may be a useful target for cognitive intervention in older adults with depression symptoms. Reduced hippocampal volumes did not mediate this relationship, indicating a broader distributed neural network may underpin these associations.