Incidence and predictors of adherence to sleep apnea treatment in rehabilitation inpatients with acquired brain injury.

OBJECTIVE: The purpose of this study was to describe incidence and assess predictors of adherence to Positive Airway Pressure (PAP) therapy for Obstructive Sleep Apnea (OSA) in persons with acquired brain injury (ABI). METHODS: A 2012-2015 retrospective analysis of consecutive ABI patients admitted for neurorehabilitation, referred for polysomnography (PSG), and prescribed PAP for OSA. Univariable linear regressions were conducted to examine predictors of average hours of nightly PAP use. Univariable logistic regressions were conducted to examine predictors of PAP adherence using the conventional clinical definition of ≥4 h per night ≥70% of the time. Persons with traumatic etiology were separately analyzed. RESULTS: ABI etiology was 51% traumatic, 36% stroke, and 13% other nontraumatic causes. Nearly two-thirds were nonadherent to PAP. For the overall sample, higher average nightly PAP usage was significantly predicted by positive hypertension diagnosis (ß = 0.271, p = 0.019). Likewise, greater adherence based on the conventional cutoff was predicted by poorer motor functioning at hospital admission (OR = 0.98, p = 0.001) and lower oxygen saturation nadir (OR = 0.99, p = 0.003). For those with traumatic injuries, greater adherence was predicted by poorer functional status at hospital admission (OR = 0.98, p = 0.010) and positive hypertension diagnosis (OR = 0.16, p = 0.023). CONCLUSIONS: In this study of hospitalized neurorehabilitation patients with ABI and comorbid OSA, predictors of adherence included lower oxygen saturation, poorer functional status and hypertension diagnosis, perhaps signifying the role of greater severity of illness on treatment adherence. High rates of refusal and nonadherence to frontline PAP therapy for sleep apnea is a concern for persons in recovery form ABI who are at a time of critical neural repair.

Lower Aerobic Endurance Linked to History of Depression in Multiple Sclerosis: Preliminary Observations.

BACKGROUND: Despite the demonstrated benefits of exercise in multiple sclerosis (MS), this population shows low rates of physical activity. Understanding barriers to exercise in persons with MS is important. The current study examined the relationship between lifetime history of depression, current depressive symptoms, and aerobic endurance in persons with relapsing-remitting MS to determine whether depression might be one such barrier. METHODS: Thirty-one participants with relapsing-remitting MS self-reported current depressive symptoms and history of depression. Aerobic endurance was assessed via 2-Minute Step Test. RESULTS: Linear regression demonstrated that lifetime history of depression predicted lower aerobic fitness whereas current depressive symptoms did not. CONCLUSIONS: Findings suggest a possible role of lifetime depression as a barrier to exercise in MS and highlight the importance of effective treatment of depression in this population to reduce its potential impact on exercise adherence.

The Moderating Role of Insulin-Like Growth Factor 1 in the Relationship Between Cognitive and Aerobic Endurance Change.

BACKGROUND: Improvements in cognition often accompany fitness improvements in older adults, and research suggests insulin-like growth factor 1 (IGF-1) may influence this association. No prior work has examined this in mild cognitive impairment (MCI). We predicted that IGF-1 would moderate the relationship between cognition and aerobic endurance improvement, such that greater baseline IGF-1 would accompany a stronger relationship between cognition and aerobic endurance change. METHOD: Twenty-seven individuals with MCI completed assessments of aerobic endurance (2-minute step test [2MST]) and global cognition (Modified Mini-Mental State [3MS]) before and after a 6-month period of twice-weekly exercise. Serum IGF-1 levels were assessed at baseline via fasted blood draw. The Johnson-Neyman technique determined whether baseline IGF-1 levels moderated the relationship between changes in aerobic endurance (Δ2MST) and cognition (Δ3MS). RESULTS: A significant interaction was found; however, Δ2MST was inversely associated with Δ3MS in individuals with above-average serum IGF-1 levels; this relationship was strengthened as IGF-1 increased and was not seen when IGF-1 was below average. CONCLUSION: The relationship between cognitive and aerobic endurance change varies as a function of IGF-1 in persons with MCI. Additional work is needed to clarify the mechanisms of these findings.

Higher fasting glucose is associated with poorer cognition among healthy young adults.

OBJECTIVE: Obesity is associated with cognitive deficits; however, the mechanisms are unclear, especially among otherwise healthy adults. Our objectives were to examine (a) whether obesity is linked to elevations in fasting glucose and (b) whether these elevations are associated with cognitive impairment among otherwise healthy young adults. METHOD: Participants were 35 normal weight adults and 35 young adults with obesity who completed a task from the Automated Neuropsychological Assessment Metrics-4 (ANAM-4). Measured body mass index (BMI) and fasting blood glucose levels (mg/dL) were examined. RESULTS: Persons with obesity had higher fasting glucose levels than normal weight persons (p = .03). After applying Bonferroni correction for multiple tests, higher fasting glucose predicted less accurate performance on tests of inhibitory control: Go/No-Go Commission Errors (ß = .33, p = .004). No effects were observed for sustained attention or working memory (ps ≥. 049). Persons with glucose levels in the prediabetes range had nearly twice as many errors as those with normal glucose, a large effect that was independent of BMI. CONCLUSIONS: Young adults who were obese but otherwise healthy had higher fasting glucose levels compared with normal weight peers. Higher glucose levels were associated with poorer cognitive performance on tests of inhibitory control, especially among individuals with prediabetes levels. Thus, subclinical elevations in blood glucose may contribute to cognitive impairment and, ultimately, greater impulsivity-well in advance of the development of chronic disease states (e.g., insulin resistance or Type 2 diabetes) and independently of excess adiposity--though prospective studies are needed to determine directionality of this relationship.

Dairy intake is associated with memory and pulsatility index in heart failure.

PURPOSE/AIM: Past work shows an inconsistent relationship between dairy intake and cognition in healthy older adults. A cross-sectional design was conducted to examine dairy consumption, cognitive dysfunction, and cerebral blood flow in a sample of older adults with heart failure (HF) to clarify their association in this population at high risk for adverse neurocognitive outcomes. MATERIALS AND METHODS: A total of 86 older adults with HF (70.39 ± 9.51 years; 33.1% female) underwent neuropsychological testing, transcranial Doppler (TCD) sonography to quantify cerebral blood flow. Dairy intake was quantified using a brief self-report questionnaire. RESULTS: Partial correlations between the dairy consumption questionnaire and neuropsychological tests were conducted adjusting for HF severity, age, and sex. Contrary to expectations, results showed greater dairy intake was associated with poorer memory (r = -0.21, p = 0.01) and higher pulsatility index in the medial cerebral artery (r = -0.17, p = 0.05). CONCLUSION: Results suggest that greater dairy intake was associated with poorer memory performance in older adults with HF. Several possible explanations for these findings exist, including the contribution of high-fat dairy to underlying physiological processes that promote vascular cognitive impairment. Prospective studies employing objective measures specific to high and low fat dairy are needed to clarify this possibility.

Higher serum insulin-like growth factor-1 is associated with better cognitive performance in persons with mild cognitive impairment.

BACKGROUND: Serum insulin-like growth factor-1 (IGF-1) is a mitogenic peptide involved in the regulation of cell proliferation, differentiation, and apoptosis in a wide variety of cells and tissues. Recent research suggests higher circulating levels of IGF-1 are associated with better cognitive performance in healthy older adults and in early stages of Alzheimer's disease, although the cognitive profile associated with elevated IGF-1 has not been examined in persons with mild cognitive impairment. METHODS: Thirty-one participants (age: 83.71 ± 3.59 years; 58% women) with mild cognitive impairment completed neuropsychological testing and 12-hour fasting blood draw to assess serum IGF-1. RESULTS: Partial correlations between serum IGF-1 and neuropsychological measures were conducted, adjusting for insulin, body mass index, and age. Higher IGF-1-values were associated with better global cognition (Modified Mini Mental State Exam: r = 0.39, P = 0.04) and verbal list learning (Hopkins Verbal Learning Test learning: r = 0.38, P = 0.05), Hopkins Verbal Learning Test free recall (r = 0.41, P = 0.03), and Hopkins Verbal Learning Test recognition discriminability (r = 0.46, P = 0.01). A similar trend emerged for executive function as tested by the Frontal Assessment Battery (r = 0.33, P = 0.09). CONCLUSION: Results suggest higher levels of serum IGF-1 are associated with better cognitive performance in persons with mild cognitive impairment, particularly on tests of learning and memory. These findings suggest IGF-1 may be neuroprotective not only in healthy older adults, but also in adults in the earliest stages of Alzheimer's disease. Further investigation is needed to clarify the nature of this relationship, particularly prospective studies.