Lifestyle Factors and Subjective Cognitive Impairment in Patients Seeking Help at a Memory Disorder Clinic: The Role of Negative Life Events.

BACKGROUND/AIMS: A large proportion of patients at memory disorders clinics are classified as having subjective cognitive impairment (SCI). Previous research has investigated whether particular lifestyle factors known to affect cognition can be useful in differentiating patients who do not show objective evidence of memory decline. There may also exist subgroups of patients with respect to lifestyle factors that could help clinicians to understand the patient group that presents to memory clinics. These may differ in diagnostic outcome. Very little is known about potential subgroups; however, but such information may help guide interventions and potentially eliminate unnecessary diagnostic procedures. The current study investigated patterns of lifestyle-related variables, including stress, sleep, sensory sensitivity, depression, and negative life events in patients presenting to a memory disorders clinic. The aim was to determine whether subgroups existed and whether it was possible to distinguish those with objectively impaired cognition. METHODS: One hundred and seventy-eight patients (mean age 58 years) from a University Hospital Memory Disorders Clinic. RESULTS: Cluster analysis identified three groups of lifestyle-related variables. Strong determinants of clusters were negative life events and age. Patients with a high number of negative life events also tended to have highest self-reported memory complaint, higher levels of stress, depression, and sensory sensitivity. However, they did not perform the worst on memory testing. In contrast, individuals who performed the worst on memory tests were older, tended to have the least memory complaints, and less negative lifestyle factors; this group also included the highest proportion of patients with mild cognitive impairment and had the lowest median amyloid A-beta 42 (Aß42). The group with the best cognitive performance were younger, included the highest proportion of patients with SCI and the highest median Aß42. On lifestyle variables, their ratings fell in between the other groups. CONCLUSIONS: Lifestyle subgroups of patients were determined by stress, emotional problems, and age. The groups were significantly associated with Aß42 and diagnostic outcome. This pattern may confound the differentiation between objective and subjective memory problems. Asking about lifestyle variables, in conjunction with neuropsychological testing, could potentially identify individuals who are not likely to have objective memory impairment and guide interventions.

Long-Term Cognitive Outcome and Brain Imaging in Adults After Extracorporeal Membrane Oxygenation.

OBJECTIVES: To investigate the presence of cognitive dysfunction and brain lesions in long-term survivors after treatment with extracorporeal membrane oxygenation for severe respiratory failure, and to see whether patients with prolonged hypoxemia were at increased risk. DESIGN: A single-center retrospective cohort study. SETTING: Tertiary referral center for extracorporeal membrane oxygenation in Sweden. PATIENTS: Long-term survivors treated between 1995 and July 2009. Seven patients from a previously published study investigated with a similar protocol were included. INTERVENTIONS: Brain imaging, neurocognitive testing, interview. MEASUREMENTS AND MAIN RESULTS: Thirty-eight patients (i.e., n = 31 + 7) were enrolled and investigated in median 9.0 years after discharge. Only memory tests were performed in 10 patients, mainly due to a lack of formal education necessary for the test results to be reliable. Median full-scale intelligence quotient, memory index, and executive index were 97, 101, and 104, respectively (normal, 100 ± 15). Cognitive function was not reduced in the group with prolonged hypoxemia. Brain imaging showed cerebrovascular lesions in 14 of 38 patients (37%), most commonly in the group treated with venoarterial extracorporeal membrane oxygenation (7/11, 64%). In this group, memory function and executive function were significantly reduced. CONCLUSIONS: Patients treated with extracorporeal membrane oxygenation for respiratory failure may have normal cognitive function years after treatment, if not affected by cerebrovascular lesions. Permissive hypoxemia was not correlated with long-term cognitive dysfunction in the present study. Further prospective studies with minimal loss to follow-up are direly needed to confirm our findings.

Lifestyle Factors Are Important Contributors to Subjective Memory Complaints among Patients without Objective Memory Impairment or Positive Neurochemical Biomarkers for Alzheimer's Disease.

BACKGROUND/AIMS: Many patients presenting to a memory disorders clinic for subjective memory complaints do not show objective evidence of decline on neuropsychological data, have nonpathological biomarkers for Alzheimer's disease, and do not develop a neurodegenerative disorder. Lifestyle variables, including subjective sleep problems and stress, are factors known to affect cognition. Little is known about how these factors contribute to patients' subjective sense of memory decline. Understanding how lifestyle factors are associated with the subjective sense of failing memory that causes patients to seek a formal evaluation is important both for diagnostic workup purposes and for finding appropriate interventions and treatment for these persons, who are not likely in the early stages of a neurodegenerative disease. The current study investigated specific lifestyle variables, such as sleep and stress, to characterize those patients that are unlikely to deteriorate cognitively. METHODS: Two hundred nine patients (mean age 58 years) from a university hospital memory disorders clinic were included. RESULTS: Sleep problems and having much to do distinguished those with subjective, but not objective, memory complaints and non-pathological biomarkers for Alzheimer's disease. CONCLUSIONS: Lifestyle factors including sleep and stress are useful in characterizing subjective memory complaints from objective problems. Inclusion of these variables could potentially improve health care utilization efficiency and guide interventions.

Does permissive hypoxaemia during extracorporeal membrane oxygenation cause long-term neurological impairment?: A study in patients with H1N1-induced severe respiratory failure.

BACKGROUND: The Extracorporeal Life Support Organisation accepts permissive hypoxaemia in adult patients during extracorporeal membrane oxygenation (ECMO). The neurological long-term outcome of this approach has not yet been studied. OBJECTIVES: We investigated the prevalence of brain lesions and cognitive dysfunction in survivors from the Influenza A/H1N1 2009 pandemic treated with permissive hypoxaemia during ECMO for severe acute respiratory distress syndrome (ARDS). Our hypothesis was that this method is reasonable if tissue hypoxia is avoided. DESIGN: Long-term follow-up study after ECMO. SETTING: Karolinska University Hospital, Sweden, from October 2012 to July 2013. PATIENTS: Seven patients treated with ECMO for severe influenza A/H1N1-induced ARDS were studied 3.2 years after treatment. Blood lactate concentrations were used as a surrogate for tissue oxygenation. INTERVENTIONS: Neurocognitive outcome was studied with standardised cognitive tests and MRI of the brain. MAIN OUTCOME MEASURES: Cognitive functioning and hypoxic brain lesions after permissive hypoxaemia during ECMO. The observation period was the first 10 days of ECMO or the entire treatment period if shorter than 10 days. RESULTS: Eleven of 13 patients were still alive 3 years after ECMO. We were able to contact seven of these patients (mean age 31 years), who all agreed to participate in this study. Mean ±â€ŠSD peripherally measured arterial saturation during the observation period was 79 ±â€Š10%. Full-scale Intelligence Quotient was within one standard deviation or above from the mean of a healthy population in five patients, and was 1.5 SD below the mean in one patient. In one other patient, it could not be determined because of a lack of formal education. Memory functioning was normal in all patients. MRI showed no changes related to cerebral hypoxia. CONCLUSIONS: Permissive hypoxaemia during ECMO might not negatively affect long-term cognitive outcome if adequate organ perfusion is maintained. TRIAL REGISTRATION: at Clinicaltrials.gov NCT01763060.

Positive Modulation of the Glycine Receptor by Means of Glycine Receptor-Binding Aptamers.

According to the gate control theory of pain, the glycine receptors (GlyRs) are putative targets for development of therapeutic analgesics. A possible approach for novel analgesics is to develop a positive modulator of the glycine-activated Cl(-) channels. Unfortunately, there has been limited success in developing drug-like small molecules to study the impact of agonists or positive modulators on GlyRs. Eight RNA aptamers with low nanomolar affinity to GlyRα1 were generated, and their pharmacological properties analyzed. Cytochemistry using fluorescein-labeled aptamers demonstrated GlyRα1-dependent binding to the plasma membrane but also intracellular binding. Using a fluorescent membrane potential assay, we could identify five aptamers to be positive modulators. The positive modulation of one of the aptamers was confirmed by patch-clamp electrophysiology on L(tk) cells expressing GlyRα1 and/or GlyRα1ß. This aptamer potentiated whole-cell Cl(-) currents in the presence of low concentrations of glycine. To our knowledge, this is the first demonstration ever of RNA aptamers acting as positive modulators for an ion channel. We believe that these aptamers are unique and valuable tools for further studies of GlyR biology and possibly also as tools for assay development in identifying small-molecule agonists and positive modulators.

Presymptomatic cognitive and neuroanatomical changes in genetic frontotemporal dementia in the Genetic Frontotemporal dementia Initiative (GENFI) study: a cross-sectional analysis.

BACKGROUND: Frontotemporal dementia is a highly heritable neurodegenerative disorder. In about a third of patients, the disease is caused by autosomal dominant genetic mutations usually in one of three genes: progranulin (GRN), microtubule-associated protein tau (MAPT), or chromosome 9 open reading frame 72 (C9orf72). Findings from studies of other genetic dementias have shown neuroimaging and cognitive changes before symptoms onset, and we aimed to identify whether such changes could be shown in frontotemporal dementia. METHODS: We recruited participants to this multicentre study who either were known carriers of a pathogenic mutation in GRN, MAPT, or C9orf72, or were at risk of carrying a mutation because a first-degree relative was a known symptomatic carrier. We calculated time to expected onset as the difference between age at assessment and mean age at onset within the family. Participants underwent a standardised clinical assessment and neuropsychological battery. We did MRI and generated cortical and subcortical volumes using a parcellation of the volumetric T1-weighted scan. We used linear mixed-effects models to examine whether the association of neuropsychology and imaging measures with time to expected onset of symptoms differed between mutation carriers and non-carriers. FINDINGS: Between Jan 30, 2012, and Sept 15, 2013, we recruited participants from 11 research sites in the UK, Italy, the Netherlands, Sweden, and Canada. We analysed data from 220 participants: 118 mutation carriers (40 symptomatic and 78 asymptomatic) and 102 non-carriers. For neuropsychology measures, we noted the earliest significant differences between mutation carriers and non-carriers 5 years before expected onset, when differences were significant for all measures except for tests of immediate recall and verbal fluency. We noted the largest Z score differences between carriers and non-carriers 5 years before expected onset in tests of naming (Boston Naming Test -0·7; SE 0·3) and executive function (Trail Making Test Part B, Digit Span backwards, and Digit Symbol Task, all -0·5, SE 0·2). For imaging measures, we noted differences earliest for the insula (at 10 years before expected symptom onset, mean volume as a percentage of total intracranial volume was 0·80% in mutation carriers and 0·84% in non-carriers; difference -0·04, SE 0·02) followed by the temporal lobe (at 10 years before expected symptom onset, mean volume as a percentage of total intracranial volume 8·1% in mutation carriers and 8·3% in non-carriers; difference -0·2, SE 0·1). INTERPRETATION: Structural imaging and cognitive changes can be identified 5-10 years before expected onset of symptoms in asymptomatic adults at risk of genetic frontotemporal dementia. These findings could help to define biomarkers that can stage presymptomatic disease and track disease progression, which will be important for future therapeutic trials. FUNDING: Centres of Excellence in Neurodegeneration.

Engineering neprilysin activity and specificity to create a novel therapeutic for Alzheimer's disease.

Neprilysin is a transmembrane zinc metallopeptidase that degrades a wide range of peptide substrates. It has received attention as a potential therapy for Alzheimer's disease due to its ability to degrade the peptide amyloid beta. However, its broad range of peptide substrates has the potential to limit its therapeutic use due to degradation of additional peptides substrates that tightly regulate many physiological processes. We sought to generate a soluble version of the ectodomain of neprilysin with improved activity and specificity towards amyloid beta as a potential therapeutic for Alzheimer's disease. Extensive amino acid substitutions were performed at positions surrounding the active site and inner surface of the enzyme and variants screened for activity on amyloid beta 1-40, 1-42 and a variety of other physiologically relevant peptides. We identified several mutations that modulated and improved both enzyme selectivity and intrinsic activity. Neprilysin variant G399V/G714K displayed an approximately 20-fold improved activity on amyloid beta 1-40 and up to a 3,200-fold reduction in activity on other peptides. Along with the altered peptide substrate specificity, the mutant enzyme produced a markedly altered series of amyloid beta cleavage products compared to the wild-type enzyme. Crystallisation of the mutant enzyme revealed that the amino acid substitutions result in alteration of the shape and size of the pocket containing the active site compared to the wild-type enzyme. The mutant enzyme offers the potential for the more efficient degradation of amyloid beta in vivo as a therapeutic for the treatment of Alzheimer's disease.

Sustained peripheral depletion of amyloid-ß with a novel form of neprilysin does not affect central levels of amyloid-ß.

Alzheimer's disease is characterized by the accumulation of amyloid deposits in the brain and the progressive loss of cognitive functions. Although the precise role of amyloid-ß in disease progression remains somewhat controversial, many efforts to halt or reverse disease progression have focussed on reducing its synthesis or enhancing its removal. It is believed that brain and peripheral soluble amyloid-ß are in equilibrium and it has previously been hypothesized that a reduction in peripheral amyloid-ß can lower brain amyloid-ß, thereby reducing formation of plaques predominantly composed of insoluble amyloid-ß; the so-called peripheral sink hypothesis. Here we describe the use of an amyloid-ß degrading enzyme, the endogenous metallopeptidase neprilysin, which is fused to albumin to extend plasma half-life and has been engineered to confer increased amyloid-ß degradation activity. We used this molecule to investigate the effect of degradation of peripheral amyloid-ß on amyloid-ß levels in the brain and cerebrospinal fluid after repeated intravenous dosing for up to 4 months in Tg2576 transgenic mice, and 1 month in rats and monkeys. This molecule proved highly effective at degradation of amyloid-ß in the periphery but did not alter brain or cerebrospinal fluid amyloid-ß levels, suggesting that the peripheral sink hypothesis is not valid and is the first time that this has been demonstrated in non-human primates.

Increasing CSF phospho-tau levels during cognitive decline and progression to dementia.

BACKGROUND: Little is known about longitudinal changes of cerebrospinal fluid (CSF) biomarkers during cognitive decline in neurodegenerative disease progression. OBJECTIVE: To investigate longitudinal changes in CSF biomarkers--total-tau (T-tau), phospho-tau (P-tau) and beta-amyloid (Abeta42)--during cognitive decline. METHODS: Forty memory clinic patients (47.5% females), aged 61.3+/-7.6 (S.D.) years, non-demented at baseline, underwent lumbar puncture and neuropsychological testing at two occasions. Baseline mean MMSE-score was 28.3+/-1.8. Patients were divided into three groups based on baseline memory functioning; severely impaired (SIM), moderately impaired (MIM) and no impairment (NIM). RESULTS: There was a significant increase in P-tau in the SIM-group during follow-up, while P-tau in MIM and NIM did not change. Eighty-three percent of the SIM-patients converted to dementia (80% AD), while most MIM- and NIM-patients remained non-demented. T-tau- and Abeta42-levels did not change in any of the memory groups during follow-up. CONCLUSION: Increasing P-tau levels during cognitive decline and conversion to dementia suggest that P-tau may be useful as a longitudinal marker of the neurodegenerative process.

Differential CSF biomarker levels in APOE-epsilon4-positive and -negative patients with memory impairment.

OBJECTIVES: To investigate the relationships between episodic memory, APOE genotype, CSF markers (total tau, T-tau; phospho-tau, P-tau; beta-amyloid, Abeta42) and longitudinal cognitive decline. METHODS: 124 memory clinic patients were retrospectively divided into 6 groups based on (i) episodic memory function (Rey Auditory Verbal Learning Test, RAVLT): severe, moderate or no impairment (SIM, MIM or NIM), and (ii) APOE genotype (epsilon4+ or epsilon4-). CSF marker levels and cognitive decline were compared across groups. RESULTS: Episodic memory function, according to RAVLT scores, was significantly correlated with CSF marker levels only among epsilon4+ subjects and not among epsilon4- subjects. When comparing the 6 subgroups, SIM epsilon4+ and MIM epsilon4+ groups showed significantly lower Abeta42 levels than the other groups. T-tau and P-tau levels were significantly increased in SIM epsilon4+ when compared to all the other groups, including the SIM epsilon4- group. However, both SIM epsilon4+ and SIM epsilon4- declined cognitively during the follow-up. CONCLUSION: It remains to be determined whether APOE genotype affects the expression of biomarkers in CSF, or whether the different biomarker patterns reflect different types of disease processes in patients with progressive cognitive dysfunction.

Achieving directed immunostimulating complexes incorporation.

In recent years, several studies have been reported with the common aim of generating general expression systems for straightforward production and subsequent coupling of expressed antigens to an adjuvant system. Here, we describe a series of such efforts with a common theme of using gene fusion technology for association of recombinant antigens to immunostimulating complexes (iscoms). In the early stages of vaccine development, uniform antigen preparations are crucial to allow the comparison of immune responses to different antigens, or even subdomains thereof, and we believe that the described systems constitute an important development in this context.

Identifying patients at high and low risk of cognitive decline using Rey Auditory Verbal Learning Test among middle-aged memory clinic outpatients.

OBJECTIVES: To investigate whether application of cutoff levels in an episodic memory test (Rey Auditory Verbal Learning Test, RAVLT) is a useful method for identifying patients at high and low risk of cognitive decline and subsequent dementia. METHODS: 224 patients with memory complaints (mean age = 60.7 years, mean MMSE = 28.2) followed-up at a memory clinic over approximately 3 years were assigned retrospectively to one of three memory groups from their baseline results in RAVLT [severe (SIM), moderate (MIM) or no impairment (NIM)]. These groups were investigated regarding cognitive decline. RESULTS: Patients assigned to SIM showed significant cognitive decline and progressed to dementia at a high rate, while a normal performance in RAVLT at baseline (NIM) predicted normal cognition after 3 years. Patients with MIM constituted a heterogeneous group; some patients deteriorated cognitively, while the majority remained stable or improved. CONCLUSIONS: The application of cutoff levels in RAVLT at baseline showed that patients with severely impaired RAVLT performance were at a high risk of cognitive decline and progression to dementia, while patients with normal RAVLT results did not show cognitive decline during 3 years. Furthermore, the initial degree of memory impairment was decisive in the cognitive prognosis 3 years later.

General strategies for efficient adjuvant incorporation of recombinant subunit immunogens.

We have previously reported strategies for Escherichia coli production of recombinant immunogens fused to hydrophobic peptides or lipid tags to improve their capacity to be incorporated into an adjuvant formulation, e.g., immunostimulating complexes (iscoms). Recently, we also explored the strong interaction between biotin and streptavidin to achieve iscom association of recombinant immunogens. Plasmodium falciparum,Toxoplasma gondii and Neospora caninum antigens have served as model immunogens in the different studies. Generated fusion proteins have been found to be successfully incorporated into iscoms and high-titer antigen-specific antibody responses have been obtained upon immunization of mice. We believe that the different concepts presented, utilizing either hydrophobic peptide or lipid tags, or the recently explored biotin-streptavidin principle, offer convenient methods to achieve efficient adjuvant incorporation of recombinant immunogens.