Phase Ib study of eprenetapopt (APR-246) in combination with pembrolizumab in patients with advanced or metastatic solid tumors

Background

We conducted a phase I, multicenter, open-label, dose-finding, and expansion study to determine the safety and preliminary efficacy of eprenetapopt (APR-246) combined with pembrolizumab in patients with advanced/metastatic solid tumors (ClinicalTrials.gov NCT04383938).

Patients and methods

For dose-finding, requirements were non-central nervous system primary solid tumor, intolerant to/progressed after ≥1 line of treatment, and eligible for pembrolizumab; for expansion: (i) gastric/gastroesophageal junction tumor, intolerant to/progressed after first-line treatment, and no prior anti-programmed cell death receptor-1 (PD-1)/programmed death-ligand 1 (PD-L1) therapy; (ii) bladder/urothelial tumor, intolerant to/progressed after first-line cisplatin-based chemotherapy, and no prior anti-PD-1/PD-L1 therapy; (iii) non-small-cell lung cancer (NSCLC) with previous anti-PD-1/PD-L1 therapy. Patients received eprenetapopt 4.5 g/day intravenously (IV) on days 1-4 with pembrolizumab 200 mg IV on day 3 in each 21-day cycle. Primary endpoints were dose-limiting toxicity (DLT), adverse events (AEs), and recommended phase II dose (RP2D) of eprenetapopt.

Results

Forty patients were enrolled (median age 66 years; range 27-85) and 37 received eprenetapopt plus pembrolizumab. No DLTs were reported and the RP2D for eprenetapopt in combination was 4.5 g/day IV on days 1-4. The most common eprenetapopt-related AEs were dizziness (35.1%), nausea (32.4%), and vomiting (29.7%). AEs leading to eprenetapopt discontinuation occurred in 2/37 patients (5.4%). In efficacy-assessable patients (n = 29), one achieved complete response (urothelial cancer), two achieved partial responses (NSCLC, urothelial cancer), and six patients had stable disease.

Conclusions

The eprenetapopt plus pembrolizumab combination was well tolerated with an acceptable safety profile and showed clinical activity in patients with solid tumors.

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Eprenetapopt in combination with pembrolizumab was well tolerated with an acceptable safety profile.

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Eprenetapopt plus pembrolizumab demonstrated clinical activity in heavily pre-treated patients with solid tumors.

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This is the first clinical trial evaluating the combination of a p53 reactivator with immuno-oncology therapy.

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This work informs the development of treatment combining immunotherapy with agents targeting specific pathways such as p53.

70 Prevalence of Sarcopenia in A Longitudinal UK Cohort Study Using Ewgsop2 Criteria Varies Widely Depending on Which Measures of Muscle Strength and Performance are Used

Background

The European Working Group on Sarcopenia in Older People 2 (EWGSOP2) guidelines have recently been published to aid diagnosis of sarcopenia in the clinical setting and to allow for better comparison between research studies. The guidelines recommend several different tests for diagnosing sarcopenia. We hypothesised that the prevalence of sarcopenia might vary depending on which tests are used.

Methods

We used data from Wave 3 of the Lothian Birth Cohort 1936 study, a longitudinal ageing study of healthy, community dwelling older adults (n= 697, 52% men, mean age 76y), to assess the prevalence of sarcopenia using the suggested cut-offs in the EWGSOP2 guidelines. Probable sarcopenia was defined as low muscle strength (measured by handgrip strength and 5x chair stand test), confirmed sarcopenia was defined as low muscle strength + low lean mass (measured by bioimpedance analysis), and severe sarcopenia was defined as confirmed sarcopenia + low muscle performance (measured by gait speed and short physical performance battery score). SPSS version 24.0 was used for statistical analysis.

Results

The maximum prevalence of probable sarcopenia was 24.2% in men and 24.8% in women, of confirmed sarcopenia was 7.4% in men and 11.0% in women, and of severe sarcopenia was 4.6% in men and 5.9% in women, when either of the cut-offs for muscle strength +/- muscle performance were met. When using only one measure of muscle strength +/- performance, rates of probable sarcopenia ranged from 7.7% to 21.1% in men and 5.9% to 21.3% in women; rates of confirmed sarcopenia ranged from 3.9% to 5.3% in men and 5.1% to 9% in women; and rates of severe sarcopenia ranged from 1.4% to 3.9% in men and from 2.0% to 5.1% in women.

Conclusions

In a UK-based longitudinal ageing study we found that the prevalence of probable, confirmed and severe sarcopenia varied widely using the EWGSOP2 guidelines depending on which identifying tests were used. We found that the cut-off points suggested for some of the measures in the guidelines are not comparable and may lead to differing groups being identified as sarcopenic between different trials. We suggest modification of the cut-offs to adjust for this.

Associations between Dietary Inflammatory Index Scores and Inflammatory Biomarkers among Older Adults in the Lothian Birth Cohort 1936 Study

OBJECTIVES

Chronic low-grade inflammation is a key underlying mechanism in several age-related chronic conditions and previous studies have shown that diet can modulate the inflammatory process. We investigated the ability of the Dietary Inflammatory Index (DII®), a summary measure of dietary inflammatory potential, to predict concentrations of plasma inflammatory markers in a sample of older people.

DESIGN

Cross-sectional and 3-year follow-up analysis of Lothian Birth Cohort 1936 (LBC1936) study data.

SETTING

Baseline data collection occurred between 2004 and 2007 in Edinburgh, Scotland.

PARTICIPANTS

Men and women (n 928, age ~70 at baseline) living in Edinburgh and surrounding regions who are surviving participants of the Scottish Mental Survey of 1947.

MEASUREMENTS

Energy-adjusted DII (E-DII) scores at age 70 (derived from a food-frequency questionnaire), plasma concentrations of inflammatory biomarkers at age 70 (C-reactive protein (CRP), fibrinogen) and age 73 (CRP, fibrinogen, hs-CRP, Interleukin-6 (IL-6)). Analyses were performed using multivariable logistic regression adjusting for age, sex, smoking, body mass index, physical activity, and hypercholesterolaemia.

RESULTS

Higher E-DII scores (pro-inflammatory diet) were associated with increased odds of elevated CRP (>3mg/L) at age 70 (OR 1.12; 95% CI: 1.02, 1.24, P = 0.02), and elevated IL-6 (>1.6pg/ml) at age 73 (OR 1.11; 95% CI: 1.00, 1.23, P = 0.04), but not with fibrinogen.

CONCLUSION

These results are consistent with the ability of the DII to predict inflammatory biomarker concentrations and suggest that diet plays a role in the regulation of inflammation, even after controlling for potential confounders. This validation study provides support for using the DII in research among older populations.

Variability of pyrethroid concentrations on hard surface kitchen flooring in occupied housing

Pyrethroids are a class of neurotoxic insecticides, and some studies have used single-time wiping of hard surface flooring to estimate indoor pyrethroid concentrations. Considering that human activities may affect concentrations, knowledge of temporal variability is needed to reduce the uncertainty of exposure estimates that are calculated using wipe sampling of pyrethroids in occupied housing. During weeks one, two, and six of a 6-week study, two wipe samples of hard surface kitchen flooring were collected in each of 50 occupied residences and used to estimate the temporal variability of eight pyrethroids and six pyrethroid degradation products. Beginning 1 month prior to sample collection, the participants kept pesticide use diaries. All pyrethroids were widely distributed among the houses, and co-occurrence of multiple pyrethroids was common structured. Application diaries and detection frequencies appeared unconnected, but the applications were correlated with measurable changes in pyrethroid concentrations. In general, degradation products were detected less frequently and at lower concentrations than their parent pyrethroids. Estimates of the intraclass correlation coefficient (ICC) for individual pyrethroids ranged from 0.55 (bifenthrin) to 0.80 (deltamethrin), and two sampling events at each residence would have been sufficient to estimate the mean concentration of most pyrethroids with an ICC of 0.80.

Brain age predicts mortality

Age-associated disease and disability are placing a growing burden on society. However, ageing does not affect people uniformly. Hence, markers of the underlying biological ageing process are needed to help identify people at increased risk of age-associated physical and cognitive impairments and ultimately, death. Here, we present such a biomarker, 'brain-predicted age', derived using structural neuroimaging. Brain-predicted age was calculated using machine-learning analysis, trained on neuroimaging data from a large healthy reference sample (N=2001), then tested in the Lothian Birth Cohort 1936 (N=669), to determine relationships with age-associated functional measures and mortality. Having a brain-predicted age indicative of an older-appearing brain was associated with: weaker grip strength, poorer lung function, slower walking speed, lower fluid intelligence, higher allostatic load and increased mortality risk. Furthermore, while combining brain-predicted age with grey matter and cerebrospinal fluid volumes (themselves strong predictors) not did improve mortality risk prediction, the combination of brain-predicted age and DNA-methylation-predicted age did. This indicates that neuroimaging and epigenetics measures of ageing can provide complementary data regarding health outcomes. Our study introduces a clinically-relevant neuroimaging ageing biomarker and demonstrates that combining distinct measurements of biological ageing further helps to determine risk of age-related deterioration and death.

GWAS meta-analysis reveals novel loci and genetic correlates for general cognitive function: a report from the COGENT consortium

This corrects the article DOI: 10.1038/mp.2016.244.

GWAS meta-analysis reveals novel loci and genetic correlates for general cognitive function: a report from the COGENT consortium

The complex nature of human cognition has resulted in cognitive genomics lagging behind many other fields in terms of gene discovery using genome-wide association study (GWAS) methods. In an attempt to overcome these barriers, the current study utilized GWAS meta-analysis to examine the association of common genetic variation (~8M single-nucleotide polymorphisms (SNP) with minor allele frequency ⩾1%) to general cognitive function in a sample of 35 298 healthy individuals of European ancestry across 24 cohorts in the Cognitive Genomics Consortium (COGENT). In addition, we utilized individual SNP lookups and polygenic score analyses to identify genetic overlap with other relevant neurobehavioral phenotypes. Our primary GWAS meta-analysis identified two novel SNP loci (top SNPs: rs76114856 in the CENPO gene on chromosome 2 and rs6669072 near LOC105378853 on chromosome 1) associated with cognitive performance at the genome-wide significance level (P<5 × 10^-8). Gene-based analysis identified an additional three Bonferroni-corrected significant loci at chromosomes 17q21.31, 17p13.1 and 1p13.3. Altogether, common variation across the genome resulted in a conservatively estimated SNP heritability of 21.5% (s.e.=0.01%) for general cognitive function. Integration with prior GWAS of cognitive performance and educational attainment yielded several additional significant loci. Finally, we found robust polygenic correlations between cognitive performance and educational attainment, several psychiatric disorders, birth length/weight and smoking behavior, as well as a novel genetic association to the personality trait of openness. These data provide new insight into the genetics of neurocognitive function with relevance to understanding the pathophysiology of neuropsychiatric illness.

Dietary Iodine Exposure and Brain Structures and Cognition in Older People. Exploratory Analysis in the Lothian Birth Cohort 1936

BACKGROUND

Iodine deficiency is one of the three key micronutrient deficiencies highlighted as major public health issues by the World Health Organisation. Iodine deficiency is known to cause brain structural alterations likely to affect cognition. However, it is not known whether or how different (lifelong) levels of exposure to dietary iodine influences brain health and cognitive functions.

METHODS

From 1091 participants initially enrolled in The Lothian Birth Cohort Study 1936, we obtained whole diet data from 882. Three years later, from 866 participants (mean age 72 yrs, SD±0.8), we obtained cognitive information and ventricular, hippocampal and normal and abnormal tissue volumes from brain structural magnetic resonance imaging scans (n=700). We studied the brain structure and cognitive abilities of iodine-rich food avoiders/low consumers versus those with a high intake in iodine-rich foods (namely dairy and fish).

RESULTS

We identified individuals (n=189) with contrasting diets, i) belonging to the lowest quintiles for dairy and fish consumption, ii) milk avoiders, iii) belonging to the middle quintiles for dairy and fish consumption, and iv) belonging to the middle quintiles for dairy and fish consumption. Iodine intake was secured mostly though the diet (n=10 supplement users) and was sufficient for most (75.1%, median 193 µg/day). In individuals from these groups, brain lateral ventricular volume was positively associated with fat, energy and protein intake. The associations between iodine intake and brain ventricular volume and between consumption of fish products (including fish cakes and fish-containing pasties) and white matter hyperintensities (p=0.03) the latest being compounded by sodium, proteins and saturated fats, disappeared after type 1 error correction.

CONCLUSION

In this large Scottish older cohort, the proportion of individuals reporting extreme (low vs. high)/medium iodine consumption is small. In these individuals, low iodine-rich food intake was associated with increased brain volume shrinkage, raising an important hypothesis worth being explored for designing appropriate guidelines.

Triheptanoin treatment in patients with pediatric cardiomyopathy associated with long chain-fatty acid oxidation disorders

Long-chain fatty acid oxidation disorders (LC-FAOD) can cause cardiac hypertrophy and cardiomyopathy, often presenting in infancy, typically leading to death or heart transplant despite ongoing treatment. Previous data on triheptanoin treatment of cardiomyopathy in LC-FAOD suggested a clinical benefit on heart function during acute failure. An additional series of LC-FAOD patients with critical emergencies associated with cardiomyopathy was treated with triheptanoin under emergency treatment or compassionate use protocols. Case reports from 10 patients (8 infants) with moderate or severe cardiomyopathy associated with LC-FAOD are summarized. The majority of these patients were detected by newborn screening, with follow up confirmatory testing, including mutation analysis; all patients were managed with standard treatment, including medium chain triglyceride (MCT) oil. While on this regimen, they presented with acute heart failure requiring hospitalization and cardiac support (ventilation, ECMO, vasopressors) and, in some cases, resuscitation. The patients discontinued MCT oil and began treatment with triheptanoin, an investigational drug. Triheptanoin is expected to provide anaplerotic metabolites, to replace deficient TCA cycle intermediates and improve effective energy metabolism. Cardiac function was measured by echocardiography and ejection fraction (EF) was assessed. EF was moderately to severely impaired prior to triheptanoin treatment, ranging from 12-45%. Improvements in EF began between 2 and 21days following initiation of triheptanoin, and peaked at 33-71%, with 9 of 10 patients achieving EF in the normal range. Continued treatment was associated with longer-term stabilization of clinical signs of cardiomyopathy. The most common adverse event observed was gastrointestinal distress. Of the 10 patients, 7 have continued on treatment, 1 elected to discontinue due to tolerability issues, and 2 patients died from other causes. Two of the case histories illustrate that cardiomyopathy may also develop later in childhood and/or persist into adulthood. Overall, the presented cases suggest a therapeutic effect of triheptanoin in the management of acute cardiomyopathy associated with LC-FAOD.

Platelet-Related Variants Identified by Exomechip Meta-analysis in 157,293 Individuals

Platelet production, maintenance, and clearance are tightly controlled processes indicative of platelets' important roles in hemostasis and thrombosis. Platelets are common targets for primary and secondary prevention of several conditions. They are monitored clinically by complete blood counts, specifically with measurements of platelet count (PLT) and mean platelet volume (MPV). Identifying genetic effects on PLT and MPV can provide mechanistic insights into platelet biology and their role in disease. Therefore, we formed the Blood Cell Consortium (BCX) to perform a large-scale meta-analysis of Exomechip association results for PLT and MPV in 157,293 and 57,617 individuals, respectively. Using the low-frequency/rare coding variant-enriched Exomechip genotyping array, we sought to identify genetic variants associated with PLT and MPV. In addition to confirming 47 known PLT and 20 known MPV associations, we identified 32 PLT and 18 MPV associations not previously observed in the literature across the allele frequency spectrum, including rare large effect (FCER1A), low-frequency (IQGAP2, MAP1A, LY75), and common (ZMIZ2, SMG6, PEAR1, ARFGAP3/PACSIN2) variants. Several variants associated with PLT/MPV (PEAR1, MRVI1, PTGES3) were also associated with platelet reactivity. In concurrent BCX analyses, there was overlap of platelet-associated variants with red (MAP1A, TMPRSS6, ZMIZ2) and white (PEAR1, ZMIZ2, LY75) blood cell traits, suggesting common regulatory pathways with shared genetic architecture among these hematopoietic lineages. Our large-scale Exomechip analyses identified previously undocumented associations with platelet traits and further indicate that several complex quantitative hematological, lipid, and cardiovascular traits share genetic factors.

Genome-wide autozygosity is associated with lower general cognitive ability

Inbreeding depression refers to lower fitness among offspring of genetic relatives. This reduced fitness is caused by the inheritance of two identical chromosomal segments (autozygosity) across the genome, which may expose the effects of (partially) recessive deleterious mutations. Even among outbred populations, autozygosity can occur to varying degrees due to cryptic relatedness between parents. Using dense genome-wide single-nucleotide polymorphism (SNP) data, we examined the degree to which autozygosity associated with measured cognitive ability in an unselected sample of 4854 participants of European ancestry. We used runs of homozygosity-multiple homozygous SNPs in a row-to estimate autozygous tracts across the genome. We found that increased levels of autozygosity predicted lower general cognitive ability, and estimate a drop of 0.6 s.d. among the offspring of first cousins (P=0.003-0.02 depending on the model). This effect came predominantly from long and rare autozygous tracts, which theory predicts as more likely to be deleterious than short and common tracts. Association mapping of autozygous tracts did not reveal any specific regions that were predictive beyond chance after correcting for multiple testing genome wide. The observed effect size is consistent with studies of cognitive decline among offspring of known consanguineous relationships. These findings suggest a role for multiple recessive or partially recessive alleles in general cognitive ability, and that alleles decreasing general cognitive ability have been selected against over evolutionary time.

Do white matter hyperintensities mediate the association between brain iron deposition and cognitive abilities in older people?

BACKGROUND AND PURPOSE

Several studies have reported associations between brain iron deposits (IDs), white matter hyperintensities (WMHs) and cognitive ability in older individuals. Whether the association between brain IDs and cognitive abilities in older people is mediated by or independent of total brain tissue damage represented by WMHs visible on structural magnetic resonance imaging (MRI) was examined.

METHODS

Data from 676 community-dwelling individuals from the Lothian Birth Cohort 1936, with Mini-Mental State Examination scores >24, who underwent detailed cognitive testing and multimodal brain MRI at mean age 72.7 years were analysed. Brain IDs were assessed automatically following manual editing. WMHs were assessed semi-automatically. Brain microbleeds were visually counted. Structural equation modelling was used to test for mediation.

RESULTS

Overall, 72.8% of the sample had IDs with a median total volume of 0.040 ml (i.e. 0.004% of the total brain volume). The total volume of IDs, significantly and negatively associated with general cognitive function (standardized β = -0.17, P < 0.01), was significantly and positively associated with WMH volume (std β = 0.13, P = 0.03). WMH volume had a significant negative association with general cognitive function, independent of IDs (std β = -0.13, P < 0.01). The association between cognition and IDs in the brain stem (and minimally the total brain iron load) was partially and significantly mediated by WMH volume (P = 0.03).

CONCLUSIONS

The negative association between brain IDs and cognitive ability in the elderly is partially mediated by WMHs, with this mediation mainly arising from the iron deposition load in the brain stem. IDs might be an indicator of small vessel disease that predisposes to white matter damage, affecting the neuronal networks underlying higher cognitive functioning.

Common polygenic risk for autism spectrum disorder (ASD) is associated with cognitive ability in the general population

Cognitive impairment is common among individuals diagnosed with autism spectrum disorder (ASD) and attention-deficit hyperactivity disorder (ADHD). It has been suggested that some aspects of intelligence are preserved or even superior in people with ASD compared with controls, but consistent evidence is lacking. Few studies have examined the genetic overlap between cognitive ability and ASD/ADHD. The aim of this study was to examine the polygenic overlap between ASD/ADHD and cognitive ability in individuals from the general population. Polygenic risk for ADHD and ASD was calculated from genome-wide association studies of ASD and ADHD conducted by the Psychiatric Genetics Consortium. Risk scores were created in three independent cohorts: Generation Scotland Scottish Family Health Study (GS:SFHS) (n=9863), the Lothian Birth Cohorts 1936 and 1921 (n=1522), and the Brisbane Adolescent Twin Sample (BATS) (n=921). We report that polygenic risk for ASD is positively correlated with general cognitive ability (beta=0.07, P=6 × 10(-7), r(2)=0.003), logical memory and verbal intelligence in GS:SFHS. This was replicated in BATS as a positive association with full-scale intelligent quotient (IQ) (beta=0.07, P=0.03, r(2)=0.005). We did not find consistent evidence that polygenic risk for ADHD was associated with cognitive function; however, a negative correlation with IQ at age 11 years (beta=-0.08, Z=-3.3, P=0.001) was observed in the Lothian Birth Cohorts. These findings are in individuals from the general population, suggesting that the relationship between genetic risk for ASD and intelligence is partly independent of clinical state. These data suggest that common genetic variation relevant for ASD influences general cognitive ability.

GWAS for executive function and processing speed suggests involvement of the CADM2 gene

To identify common variants contributing to normal variation in two specific domains of cognitive functioning, we conducted a genome-wide association study (GWAS) of executive functioning and information processing speed in non-demented older adults from the CHARGE (Cohorts for Heart and Aging Research in Genomic Epidemiology) consortium. Neuropsychological testing was available for 5429-32,070 subjects of European ancestry aged 45 years or older, free of dementia and clinical stroke at the time of cognitive testing from 20 cohorts in the discovery phase. We analyzed performance on the Trail Making Test parts A and B, the Letter Digit Substitution Test (LDST), the Digit Symbol Substitution Task (DSST), semantic and phonemic fluency tests, and the Stroop Color and Word Test. Replication was sought in 1311-21860 subjects from 20 independent cohorts. A significant association was observed in the discovery cohorts for the single-nucleotide polymorphism (SNP) rs17518584 (discovery P-value=3.12 × 10(-8)) and in the joint discovery and replication meta-analysis (P-value=3.28 × 10(-9) after adjustment for age, gender and education) in an intron of the gene cell adhesion molecule 2 (CADM2) for performance on the LDST/DSST. Rs17518584 is located about 170 kb upstream of the transcription start site of the major transcript for the CADM2 gene, but is within an intron of a variant transcript that includes an alternative first exon. The variant is associated with expression of CADM2 in the cingulate cortex (P-value=4 × 10(-4)). The protein encoded by CADM2 is involved in glutamate signaling (P-value=7.22 × 10(-15)), gamma-aminobutyric acid (GABA) transport (P-value=1.36 × 10(-11)) and neuron cell-cell adhesion (P-value=1.48 × 10(-13)). Our findings suggest that genetic variation in the CADM2 gene is associated with individual differences in information processing speed.

Cigarette smoking and thinning of the brain's cortex

Cigarette smoking is associated with cognitive decline and dementia, but the extent of the association between smoking and structural brain changes remains unclear. Importantly, it is unknown whether smoking-related brain changes are reversible after smoking cessation. We analyzed data on 504 subjects with recall of lifetime smoking data and a structural brain magnetic resonance imaging at age 73 years from which measures of cortical thickness were extracted. Multiple regression analyses were performed controlling for gender and exact age at scanning. To determine dose-response relationships, the association between smoking pack-years and cortical thickness was tested and then repeated, while controlling for a comprehensive list of covariates including, among others, cognitive ability before starting smoking. Further, we tested associations between cortical thickness and number of years since last cigarette, while controlling for lifetime smoking. There was a diffuse dose-dependent negative association between smoking and cortical thickness. Some negative dose-dependent cortical associations persisted after controlling for all covariates. Accounting for total amount of lifetime smoking, the cortex of subjects who stopped smoking seems to have partially recovered for each year without smoking. However, it took ~25 years for complete cortical recovery in affected areas for those at the mean pack-years value in this sample. As the cortex thins with normal aging, our data suggest that smoking is associated with diffuse accelerated cortical thinning, a biomarker of cognitive decline in adults. Although partial recovery appears possible, it can be a long process.

Genetic contributions to variation in general cognitive function: a meta-analysis of genome-wide association studies in the CHARGE consortium (N=53949)

General cognitive function is substantially heritable across the human life course from adolescence to old age. We investigated the genetic contribution to variation in this important, health- and well-being-related trait in middle-aged and older adults. We conducted a meta-analysis of genome-wide association studies of 31 cohorts (N=53,949) in which the participants had undertaken multiple, diverse cognitive tests. A general cognitive function phenotype was tested for, and created in each cohort by principal component analysis. We report 13 genome-wide significant single-nucleotide polymorphism (SNP) associations in three genomic regions, 6q16.1, 14q12 and 19q13.32 (best SNP and closest gene, respectively: rs10457441, P=3.93 × 10(-9), MIR2113; rs17522122, P=2.55 × 10(-8), AKAP6; rs10119, P=5.67 × 10(-9), APOE/TOMM40). We report one gene-based significant association with the HMGN1 gene located on chromosome 21 (P=1 × 10(-6)). These genes have previously been associated with neuropsychiatric phenotypes. Meta-analysis results are consistent with a polygenic model of inheritance. To estimate SNP-based heritability, the genome-wide complex trait analysis procedure was applied to two large cohorts, the Atherosclerosis Risk in Communities Study (N=6617) and the Health and Retirement Study (N=5976). The proportion of phenotypic variation accounted for by all genotyped common SNPs was 29% (s.e.=5%) and 28% (s.e.=7%), respectively. Using polygenic prediction analysis, ~1.2% of the variance in general cognitive function was predicted in the Generation Scotland cohort (N=5487; P=1.5 × 10(-17)). In hypothesis-driven tests, there was significant association between general cognitive function and four genes previously associated with Alzheimer's disease: TOMM40, APOE, ABCG1 and MEF2C.

Exploratory analysis of dietary intake and brain iron accumulation detected using magnetic resonance imaging in older individuals: the Lothian Birth Cohort 1936

CONTEXT

Brain Iron Deposits (IDs) are associated with neurodegenerative diseases and impaired cognitive function in later life, but their cause is unknown. Animal studies have found evidence of relationships between dietary iron, calorie and cholesterol intake and brain iron accumulation.

OBJECTIVES

To investigate the relationship between iron, calorie, and cholesterol intake, blood indicators of iron status, and brain IDs in humans.

DESIGN, SETTING AND PARTICIPANTS

Cohort of 1063 community-dwelling older individuals born in 1936 (mean age 72.7years, SD=0.7) with dietary information, results from blood sample analyses and brain imaging data contemporaneously in old age.

MEASUREMENTS

Magnetic Resonance Imaging was used to assess regional volumes of brain IDs in basal ganglia, brainstem, white matter, thalamus, and cortex/border with the corticomedullary junction, using a fully automatic assessment procedure followed by individual checking/correction where necessary. Haemoglobin, red cell count, haematocrit, mean cell volume, ferritin and transferrin were obtained from blood samples and typical daily intake of iron, calories, and cholesterol were calculated from a validated food-frequency questionnaire.

RESULTS

Overall, 72.8% of the sample that had valid MRI (n=676) had brain IDs. The median total volume of IDs was 40mm3, inter-quartile range (IQR)=196. Basal ganglia IDs (median=35, IQR=159.5 mm3), were found in 70.6% of the sample. IDs in the brainstem were found in 12.9% of the sample, in the cortex in 1.9%, in the white matter in 6.1% and in the thalamus in 1.0%. The median daily intake of calories was 1808.5kcal (IQR=738.5), of cholesterol was 258.5mg (IQR=126.2) and of total iron was 11.7mg (IQR=5). Iron, calorie or cholesterol intake were not directly associated with brain IDs. However, caloric intake was associated with ferritin, an iron storage protein (p=0.01).

CONCLUSION

Our results suggest that overall caloric, iron and cholesterol intake are not associated with IDs in brains of healthy older individuals but caloric intake could be associated with iron storage. Further work is required to corroborate our findings on other samples and investigate the underlying mechanisms of brain iron accumulation.

GWAS-based pathway analysis differentiates between fluid and crystallized intelligence

Cognitive abilities vary among people. About 40-50% of this variability is due to general intelligence (g), which reflects the positive correlation among individuals' scores on diverse cognitive ability tests. g is positively correlated with many life outcomes, such as education, occupational status and health, motivating the investigation of its underlying biology. In psychometric research, a distinction is made between general fluid intelligence (gF) - the ability to reason in novel situations - and general crystallized intelligence (gC) - the ability to apply acquired knowledge. This distinction is supported by developmental and cognitive neuroscience studies. Classical epidemiological studies and recent genome-wide association studies (GWASs) have established that these cognitive traits have a large genetic component. However, no robust genetic associations have been published thus far due largely to the known polygenic nature of these traits and insufficient sample sizes. Here, using two GWAS datasets, in which the polygenicity of gF and gC traits was previously confirmed, a gene- and pathway-based approach was undertaken with the aim of characterizing and differentiating their genetic architecture. Pathway analysis, using genes selected on the basis of relaxed criteria, revealed notable differences between these two traits. gF appeared to be characterized by genes affecting the quantity and quality of neurons and therefore neuronal efficiency, whereas long-term depression (LTD) seemed to underlie gC. Thus, this study supports the gF-gC distinction at the genetic level and identifies functional annotations and pathways worthy of further investigation.

A test house study of pesticides and pesticide degradation products following an indoor application

Preexisting pesticide degradates are a concern for pesticide biomonitoring studies as exposure to them may result in overestimation of pesticide exposure. The purpose of this research was to determine whether there was significant formation and movement, of pesticide degradates over a 5-week period in a controlled indoor setting after insecticide application. Movement of the pesticides during the study was also evaluated. In a simulated crack and crevice application, commercially available formulations of fipronil, propoxur, cis/trans-permethrin, and cypermethrin were applied to a series of wooden slats affixed to the wall in one room of an unoccupied test house. Floor surface samples were collected through 35 days post-application. Concentrations of the pesticides and the following degradates were determined: 2-iso-propoxyphenol, cis/trans 3-(2,2-dichlorovinyl)-3-3-dimethyl-(1-cyclopropane) carboxylic acid, 3-phenoxybenzoic acid, fipronil sulfone, fipronil sulfide, and fipronil desulfinyl. Deltamethrin, which had never been applied, and chlorpyrifos, which had been applied several years earlier, and their degradation products, cis-3-(2,2-dibromovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid, and, 3,5,6-trichloro-2-pyridinol, respectively, were also measured. Propoxur was the only insecticide with mass movement away from the application site. There was no measurable formation or movement of the degradates. However, all degradates were present at low levels in the formulated product. These results indicate longitudinal repetitive sampling of indoor degradate levels during short-term studies, is unnecessary.

PRACTICAL IMPLICATIONS

Exposure to preexisting pesticide degradates may inflate estimates of exposure in biomonitoring studies where these compounds are used as biomarkers. To date, there is no published information on formation of pesticide degradates following an indoor application. We found that the study pesticides have low rates of degradation and are unlikely to be a significant factor affecting results of short-term (weeks) biomonitoring studies. Therefore, relatively few indoor samples are needed to estimate background levels of degradation products resulting from a recent pesticide application.

708 Common and 2010 rare DISC1 locus variants identified in 1542 subjects: analysis for association with psychiatric disorder and cognitive traits

A balanced t(1;11) translocation that transects the Disrupted in schizophrenia 1 (DISC1) gene shows genome-wide significant linkage for schizophrenia and recurrent major depressive disorder (rMDD) in a single large Scottish family, but genome-wide and exome sequencing-based association studies have not supported a role for DISC1 in psychiatric illness. To explore DISC1 in more detail, we sequenced 528 kb of the DISC1 locus in 653 cases and 889 controls. We report 2718 validated single-nucleotide polymorphisms (SNPs) of which 2010 have a minor allele frequency of <1%. Only 38% of these variants are reported in the 1000 Genomes Project European subset. This suggests that many DISC1 SNPs remain undiscovered and are essentially private. Rare coding variants identified exclusively in patients were found in likely functional protein domains. Significant region-wide association was observed between rs16856199 and rMDD (P=0.026, unadjusted P=6.3 × 10(-5), OR=3.48). This was not replicated in additional recurrent major depression samples (replication P=0.11). Combined analysis of both the original and replication set supported the original association (P=0.0058, OR=1.46). Evidence for segregation of this variant with disease in families was limited to those of rMDD individuals referred from primary care. Burden analysis for coding and non-coding variants gave nominal associations with diagnosis and measures of mood and cognition. Together, these observations are likely to generalise to other candidate genes for major mental illness and may thus provide guidelines for the design of future studies.

Predicting cognitive ability in ageing cohorts using Type 2 diabetes genetic risk

AIMS

To investigate whether there is overlap in the genetic determinants of Type 2 diabetes and cognitive ageing by testing whether a genetic risk score for Type 2 diabetes can predict variation in cognitive function in older people without dementia.

METHODS

Type 2 diabetes genetic risk scores were estimated using various single nucleotide polymorphism significance inclusion criteria from an initial genome-wide association study, the largest in Type 2 diabetes to date. Scores were available for 2775-3057 individuals, depending on the cognitive trait.

RESULTS

Type 2 diabetes genetic risk was associated with self-reported diabetes mellitus. Across varying single nucleotide polymorphism-inclusion levels, a significant association between Type 2 diabetes genetic risk and change in general cognitive function was found (median r = 0.04); however, this was such that higher Type 2 diabetes genetic risk related to higher cognitive scores.

CONCLUSIONS

To investigate more fully the source of the often observed comorbidity between Type 2 diabetes and cognitive impairment, one direction for future research will be to use cognitive ability polygenic risk scores to predict Type 2 diabetes in line with the reverse causation hypothesis that people with lower pre-morbid cognitive ability are more likely to develop Type 2 diabetes.

Childhood intelligence is heritable, highly polygenic and associated with FNBP1L

Intelligence in childhood, as measured by psychometric cognitive tests, is a strong predictor of many important life outcomes, including educational attainment, income, health and lifespan. Results from twin, family and adoption studies are consistent with general intelligence being highly heritable and genetically stable throughout the life course. No robustly associated genetic loci or variants for childhood intelligence have been reported. Here, we report the first genome-wide association study (GWAS) on childhood intelligence (age range 6-18 years) from 17,989 individuals in six discovery and three replication samples. Although no individual single-nucleotide polymorphisms (SNPs) were detected with genome-wide significance, we show that the aggregate effects of common SNPs explain 22-46% of phenotypic variation in childhood intelligence in the three largest cohorts (P=3.9 × 10(-15), 0.014 and 0.028). FNBP1L, previously reported to be the most significantly associated gene for adult intelligence, was also significantly associated with childhood intelligence (P=0.003). Polygenic prediction analyses resulted in a significant correlation between predictor and outcome in all replication cohorts. The proportion of childhood intelligence explained by the predictor reached 1.2% (P=6 × 10(-5)), 3.5% (P=10(-3)) and 0.5% (P=6 × 10(-5)) in three independent validation cohorts. Given the sample sizes, these genetic prediction results are consistent with expectations if the genetic architecture of childhood intelligence is like that of body mass index or height. Our study provides molecular support for the heritability and polygenic nature of childhood intelligence. Larger sample sizes will be required to detect individual variants with genome-wide significance.

Human cognitive ability is influenced by genetic variation in components of postsynaptic signalling complexes assembled by NMDA receptors and MAGUK proteins

Differences in general cognitive ability (intelligence) account for approximately half of the variation in any large battery of cognitive tests and are predictive of important life events including health. Genome-wide analyses of common single-nucleotide polymorphisms indicate that they jointly tag between a quarter and a half of the variance in intelligence. However, no single polymorphism has been reliably associated with variation in intelligence. It remains possible that these many small effects might be aggregated in networks of functionally linked genes. Here, we tested a network of 1461 genes in the postsynaptic density and associated complexes for an enriched association with intelligence. These were ascertained in 3511 individuals (the Cognitive Ageing Genetics in England and Scotland (CAGES) consortium) phenotyped for general cognitive ability, fluid cognitive ability, crystallised cognitive ability, memory and speed of processing. By analysing the results of a genome wide association study (GWAS) using Gene Set Enrichment Analysis, a significant enrichment was found for fluid cognitive ability for the proteins found in the complexes of N-methyl-D-aspartate receptor complex; P=0.002. Replication was sought in two additional cohorts (N=670 and 2062). A meta-analytic P-value of 0.003 was found when these were combined with the CAGES consortium. The results suggest that genetic variation in the macromolecular machines formed by membrane-associated guanylate kinase (MAGUK) scaffold proteins and their interaction partners contributes to variation in intelligence.

Introducing the GRACEnet/REAP Data Contribution, Discovery, and Retrieval System

Difficulties in accessing high-quality data on trace gas fluxes and performance of bioenergy/bioproduct feedstocks limit the ability of researchers and others to address environmental impacts of agriculture and the potential to produce feedstocks. To address those needs, the GRACEnet (Greenhouse gas Reduction through Agricultural Carbon Enhancement network) and REAP (Renewable Energy Assessment Project) research programs were initiated by the USDA Agricultural Research Service (ARS). A major product of these programs is the creation of a database with greenhouse gas fluxes, soil carbon stocks, biomass yield, nutrient, and energy characteristics, and input data for modeling cropped and grazed systems. The data include site descriptors (e.g., weather, soil class, spatial attributes), experimental design (e.g., factors manipulated, measurements performed, plot layouts), management information (e.g., planting and harvesting schedules, fertilizer types and amounts, biomass harvested, grazing intensity), and measurements (e.g., soil C and N stocks, plant biomass amount and chemical composition). To promote standardization of data and ensure that experiments were fully described, sampling protocols and a spreadsheet-based data-entry template were developed. Data were first uploaded to a temporary database for checking and then were uploaded to the central database. A Web-accessible application allows for registered users to query and download data including measurement protocols. Separate portals have been provided for each project (GRACEnet and REAP) at nrrc.ars.usda.gov/slgracenet/#/Home and nrrc.ars.usda.gov/slreap/#/Home. The database architecture and data entry template have proven flexible and robust for describing a wide range of field experiments and thus appear suitable for other natural resource research projects.

Neuroticism, depressive symptoms and white-matter integrity in the Lothian Birth Cohort 1936

BACKGROUND

Clinical depression is associated with reductions in white-matter integrity in several long tracts of the brain. The extent to which these findings are localized or related to depressive symptoms or personality traits linked to disease risk remains unclear. Method Members of the Lothian Birth Cohort 1936 (LBC936) were assessed in two waves at mean ages of 70 and 73 years. At wave 1, they underwent assessments of depressive symptoms and the personality traits of neuroticism and extraversion. Brain diffusion magnetic resonance imaging (MRI) data were obtained at the second wave and mood assessments were repeated. We tested whether depressive symptoms were related to reduced white-matter tract fractional anisotropy (FA), a measure of integrity, and then examined whether high neuroticism or low extraversion mediated this relationship.

RESULTS

Six hundred and sixty-eight participants provided useable data. Bilateral uncinate fasciculus FA was significantly negatively associated with depressive symptoms at both waves (standardized β=0.12-0.16). Higher neuroticism and lower extraversion were also significantly associated with lower uncinate FA bilaterally (standardized β=0.09-0.15) and significantly mediated the relationship between FA and depressive symptoms.

CONCLUSIONS

Trait liability to depression and depressive symptoms are associated with reduced structural connectivity in tracts connecting the prefrontal cortex with the amygdala and anterior temporal cortex. These effects suggest that frontotemporal disconnection is linked to the etiology of depression, in part through personality trait differences.

Brain white matter tract integrity as a neural foundation for general intelligence

General intelligence is a robust predictor of important life outcomes, including educational and occupational attainment, successfully managing everyday life situations, good health and longevity. Some neuronal correlates of intelligence have been discovered, mainly indicating that larger cortices in widespread parieto-frontal brain networks and efficient neuronal information processing support higher intelligence. However, there is a lack of established associations between general intelligence and any basic structural brain parameters that have a clear functional meaning. Here, we provide evidence that lower brain-wide white matter tract integrity exerts a substantial negative effect on general intelligence through reduced information-processing speed. Structural brain magnetic resonance imaging scans were acquired from 420 older adults in their early 70s. Using quantitative tractography, we measured fractional anisotropy and two white matter integrity biomarkers that are novel to the study of intelligence: longitudinal relaxation time (T1) and magnetisation transfer ratio. Substantial correlations among 12 major white matter tracts studied allowed the extraction of three general factors of biomarker-specific brain-wide white matter tract integrity. Each was independently associated with general intelligence, together explaining 10% of the variance, and their effect was completely mediated by information-processing speed. Unlike most previously established neurostructural correlates of intelligence, these findings suggest a functionally plausible model of intelligence, where structurally intact axonal fibres across the brain provide the neuroanatomical infrastructure for fast information processing within widespread brain networks, supporting general intelligence.

APOE E4 status predicts age-related cognitive decline in the ninth decade: longitudinal follow-up of the Lothian Birth Cohort 1921

Carriers of the APOE E4 allele have an increased risk of developing Alzheimer's disease. However, it is less clear whether APOE E4 status may also be involved in non-pathological cognitive ageing. The present study investigated the associations between APOE genotypes and cognitive change over 8 years in older community-dwelling individuals. APOE genotype was determined in 501 participants of the Lothian Birth Cohort 1921, whose intelligence had been measured in childhood in the Scottish Mental Survey 1932. A polymorphic variant of TOMM40 (rs10524523) was included to differentiate between the effects of the APOE E3 and E4 allelic variants. Cognitive performance on the domains of verbal memory, abstract reasoning and verbal fluency was assessed at mean age 79 years (n=501), and again at mean ages of 83 (n=284) and 87 (n=187). Using linear mixed models adjusted for demographic variables, vascular risk factors and IQ at age 11 years, possession of the APOE E4 allele was associated with a higher relative rate of cognitive decline over the subsequent 8 years for verbal memory and abstract reasoning. Individuals with the long allelic variant of TOMM40, which is linked to APOE E4, showed similar results. Verbal fluency was not affected by APOE E4 status. APOE E2 status was not associated with change in cognitive performance over 8 years. In non-demented older individuals, possession of the APOE E4 allele predicted a higher rate of cognitive decline on tests of verbal memory and abstract reasoning between 79 and 87 years. Thus, possession of the APOE E4 allele may not only predispose to Alzheimer's disease, but also appears to be a risk factor for non-pathological decline in verbal memory and abstract reasoning in the ninth decade of life.

Factors associated with symptoms of anxiety and depression in five cohorts of community-based older people: the HALCyon (Healthy Ageing across the Life Course) Programme

BACKGROUND

Symptoms of anxiety and depression are common in older people, but the relative importance of factors operating in early and later life in influencing risk is unclear, particularly in the case of anxiety.

METHOD

We used data from five cohorts in the Healthy Ageing across the Life Course (HALCyon) collaborative research programme: the Aberdeen Birth Cohort 1936, the Caerphilly Prospective Study, the Hertfordshire Ageing Study, the Hertfordshire Cohort Study and the Lothian Birth Cohort 1921. We used logistic regression to examine the relationship between factors from early and later life and risk of anxiety or depression, defined as scores of 8 or more on the subscales of the Hospital Anxiety and Depression Scale, and meta-analysis to obtain an overall estimate of the effect of each.

RESULTS

Greater neuroticism, poorer cognitive or physical function, greater disability and taking more medications were associated in cross-sectional analyses with an increased overall likelihood of anxiety or depression. Associations between lower social class, either in childhood or currently, history of heart disease, stroke or diabetes and increased risk of anxiety or depression were attenuated and no longer statistically significant after adjustment for potential confounding or mediating variables. There was no association between birth weight and anxiety or depression in later life.

CONCLUSIONS

Anxiety and depression in later life are both strongly linked to personality, cognitive and physical function, disability and state of health, measured concurrently. Possible mechanisms that might underlie these associations are discussed.

Antioxidant and B vitamin intake in relation to cognitive function in later life in the Lothian Birth Cohort 1936

BACKGROUND/OBJECTIVES

Cross-sectional and longitudinal studies provide some evidence for an association between intake of antioxidants and B vitamins, and cognitive function in later life, but intervention studies have not provided clear evidence of beneficial effects. The possibility that those with higher cognitive ability during earlier adult life consume more nutrient-rich diets in later life could provide an alternative explanation for the associations seen in observational studies.

METHODS

Survey of 1091 men and women born in 1936 living in Edinburgh, Scotland, in whom previous cognitive ability was available from intelligence quotient (IQ) measurements at age 11 years. At age 70 years, participants carried out a range of cognitive tests and completed a semiquantitative food-frequency questionnaire (FFQ).

RESULTS

A total of 882 participants returned completed FFQs from which intake of β-carotene, vitamin C, B12, folate and riboflavin was estimated. IQ at age 11 years was positively associated with dietary intake of vitamin C (P=0.048) and inversely associated with dietary intake of riboflavin (P<0.001) at age 70 years, and was higher in those taking folate supplements at age 70 years (P<0.005). Weak associations between intake of vitamins B12, C, riboflavin and folate and cognitive performance at age 70 years were attenuated by adjustment for confounding variables, including IQ at age 11 years. In the fully adjusted models, the proportion of total variance in cognitive function at age 70 years accounted for by intake of these nutrients was less than 1%.

CONCLUSION

These results provide no evidence for a clinically significant beneficial association between intake of these antioxidants and B vitamins, and cognitive function at age 70 years.

MTHFR polymorphisms and cognitive ageing in the ninth decade: the Lothian Birth Cohort 1921

Low blood levels of B vitamins have been implicated in age-associated cognitive impairment. The present study investigated the association between genetic variation in folate metabolism and age-related cognitive decline in the ninth decade of life. Both the 677C>T (rs1801133) polymorphism and the scarcely studied 1298A>C (rs1801131) polymorphism of the MTHFR gene were assessed in relation to cognitive change over 8 years in older community-dwelling individuals. MTHFR genotype was determined in 476 participants of the Lothian Birth Cohort 1921, whose intelligence was measured in childhood in the Scottish Mental Survey of 1932. Cognitive performance on the domains of verbal memory, reasoning and verbal fluency was assessed at mean age of 79 (n = 476) and again at mean ages of 83 (n = 275) and 87 (n = 180). Using linear mixed models, the MTHFR 677C>T and 1298A>C variants were not associated with the rate of cognitive change between 79 and 87 years, neither in the total sample, nor in a subsample of individuals with erythrocyte folate levels below the median. APOE E4 allele carrier status did not interact with MTHFR genotype in affecting change in cognitive performance over 8 years. No significant combined effect of the two polymorphisms was found. In conclusion, MTHFR 677C>T and 1298A>C polymorphisms were not associated with individual change in cognitive functioning in the ninth decade of life. Although polymorphisms in the MTHFR gene may cause disturbances in folate metabolism, they do not appear to be accompanied by changes in cognitive functioning in old age.

Childhood IQ and all-cause mortality before and after age 65: Prospective observational study linking the Scottish Mental Survey 1932 and the Midspan studies

OBJECTIVES

The objective was to investigate how childhood IQ related to all-cause mortality before and after age 65.

DESIGN

The Midspan prospective cohort studies, followed-up for mortality for 25 years, were linked to individuals' childhood IQ from the Scottish Mental Survey 1932.

METHODS

The Midspan studies collected data on risk factors for cardiorespiratory disease from a questionnaire and at a screening examination, and were conducted on adults in Scotland in the 1970s. An age 11 IQ from the Scottish Mental Survey 1932, a cognitive ability test conducted on 1921-born children attending schools in Scotland, was found for 938 Midspan participants. The relationship between childhood IQ and mortality risk, adjusting for adulthood socio-economic confounders, was analysed. The effect of adjustment for childhood IQ on the relationship between established risk factors (blood pressure, smoking, height and respiratory function) and mortality was also investigated.

RESULTS

For deaths occurring up to age 65, there was a 36% increased risk per standard deviation decrease (15 points) in childhood IQ which was reduced to 29% after adjusting for social class and deprivation category. There was no statistically significant relationship between childhood IQ and deaths occurring after the age of 65. Adjustment for childhood IQ attenuated the risk factor-mortality relationship in deaths occurring up to age 65, but had no effect in deaths occurring after age 65.

CONCLUSIONS

Childhood IQ was significantly related to deaths occurring up to age 65, but not to deaths occurring after age 65.

Cognitive visual perceptual deficits in patients with delirium

BACKGROUND

Delirium is a neuropsychiatric disorder characterised by severe cognitive impairment, but the specific neuropsychological profile of this condition has not yet been clearly delineated. Psychiatric symptoms of perceptual disturbance--such as hallucinations, illusions and misperceptions--are common in delirium, suggesting that patients may have deficits in the cognitive systems underlying visual perception.

METHODS

Five neuropsychological tests of visual perception were administered to 17 older patients with delirium, as well as to two control groups comprising 14 patients with Alzheimer's dementia and 18 cognitively normal patients. The Mini Mental State Examination and the Consortium to Establish a Registry for Alzheimer's Disease verbal memory test were also administered to assess the specificity of any perceptual impairments.

RESULTS

Patients with delirium scored significantly lower than cognitively normal patients on all perceptual tasks and significantly lower than patients with dementia on three of these tasks. Mini Mental State Examination scores did not differ between the delirium and dementia groups, and patients with delirium showed significantly better verbal recognition performance than those with dementia.

CONCLUSIONS

Patients with delirium have specific visual perceptual deficits that cannot be accounted for by general cognitive impairment. These novel findings provide insights into the neural mechanisms underling delirium and might help to improve clinical detection and management of the disorder. The results also support previous suggestions that cognitive perceptual deficits play a causal role in eliciting psychiatric symptoms of perceptual disturbance.

Variation in the dysbindin gene and normal cognitive function in three independent population samples

The association between DTNBP1 genotype and cognitive abilities was investigated in three population samples (1054 Scottish, 1806 Australian and 745 English) of varying age. There was evidence in each of the cohorts for association (P < 0.05) to single nucleotide polymorphisms (SNPs) and haplotypes previously shown to relate to cognition. By comparison with previous findings, these associations included measures of memory, and there was at best equivocal evidence of association with general cognitive ability. Of the SNPs typed in all three cohorts, rs2619528 and rs1011313 showed significant association with measures of executive function in two cohorts, rs1018381 showed significant association with verbal ability in one cohort and rs2619522 showed significance/marginal significance with tests of memory, speed and executive function in two cohorts. For all these SNPs, the direction and magnitude of the allelic effects were consistent between cohorts and with previous findings. In the English cohort, a previously untested SNP (rs742105) located in a distinct haplotype block upstream of the other SNPs showed the strongest significance (P < 0.01) for measures of memory but weaker significance for general cognitive ability. Our results therefore support involvement of the dysbindin gene in cognitive function, but further work is needed to clarify the specific functional variants involved and the cognitive abilities with which they are associated.

Spatio-temporal stochastic modelling of Clostridium difficile

Clostridium difficile-associated diarrhoea (CDAD) occurs sporadically or in small discrete outbreaks. Stochastic models may help to inform hospital infection control strategies. Bayesian framework using data augmentation and Markov chain Monte Carlo methods were applied to a spatio-temporal model of CDAD. Model simulations were validated against 17 months of observed data from two 30-bedded medical wards for the elderly. Simulating the halving of transmission rates of C. difficile from other patients and the environment reduced CDAD cases by 15%. Doubling the rate at which patients become susceptible increased predicted CDAD incidence by 63%. By contrast, doubling environmental load made hardly any difference, increasing CDAD incidence by only 3%. Simulation of different interventions indicates that for the same effect size, reducing patient susceptibility to infection is more effective in reducing the number of CDAD cases than lowering transmission rates.

Characterisation of user-defined health status in older adults with intellectual disabilities

BACKGROUND

Older adults with Intellectual Disabilities (ID) have an excess disease burden that standard health assessments are designed to detect. Older adults with ID have a broader concept of health with dimensions of well being in addition to absence of disease in line with the World Health Organization's health definition. We sought to characterise user-defined health status in a sample of older adults with ID.

METHODS

We administered a user-led health assessment to 57 adults with ID aged 40 years and over. Cluster analysis on user-defined health themes of participation, nutrition and hygiene/self-care identified clear separation of participants into a healthier and a less healthy group.

RESULTS

Disease burden (P = 0.002) and medication use (P = 0.003) were greater in the less healthy group. The healthier group were taller (P = 0.005), stronger (P = 0.005) and had better vision (P < 0.001) than the less healthy group. Constipation (P = 0.014), urinary incontinence (P < 0.001) and faecal incontinence (P < 0.001) were commoner in the less healthy group. There were few significant differences between health groups on the majority of standard physical-examination items.

CONCLUSIONS

There is considerable overlap between user-defined health and that assessed by standard instruments. In addition, user-defined health encompasses aspects of physical fitness not captured by traditional disease-based health models.

The brain-derived neurotrophic factor Val66Met polymorphism is associated with age-related change in reasoning skills

A polymorphism (Val66Met) in the gene encoding brain-derived neurotrophic factor (BDNF) has previously been associated with impaired hippocampal function and scores on the Logical Memory subtest of the Wechsler Memory Scale-Revised (WMS-R). Despite its widespread expression in the brain, there have been few studies examining the role of BDNF on cognitive domains, other than memory. We examined the association between BDNF Val66Met genotype and non-verbal reasoning, as measured by Raven's standard progressive matrices (Raven), in two cohorts of relatively healthy older people, one aged 79 (LBC1921) and the other aged 64 (ABC1936) years. LBC1921 and ABC1936 subjects had reasoning measured at age 11 years, using the Moray House Test (MHT), in the Scottish Mental Surveys of 1932 and 1947, respectively. BDNF genotype was significantly associated with later life Raven scores, controlling for sex, age 11 MHT score and cohort (P = 0.001). MHT, Verbal Fluency and Logical Memory scores were available, in later life, for LBC1921 only. BDNF genotype was significantly associated with age 79 MHT score, controlling for sex and age 11 MHT score (P = 0.016). In both significant associations, Met homozygotes scored significantly higher than heterozygotes and Val homozygotes. This study indicates that BDNF genotype contributes to age-related changes in reasoning skills, which are closely related to general intelligence.

White matter integrity and cognition in childhood and old age

OBJECTIVE

To test the hypothesis that white matter integrity, as measured by diffusion tensor and magnetization transfer MRI is significantly associated with cognitive ability measured in youth and old age.

METHODS

Forty, nondemented, surviving participants of the Scottish Mental Survey of 1932 underwent brain MRI and a battery of psychometric tests covering major cognitive domains and tests of information processing efficiency. IQ scores were available from age 11. Mean diffusivity, fractional anisotropy (FA), and magnetization transfer ratio (MTR) were measured in frontal and parieto-occipital white matter and centrum semiovale.

RESULTS

Centrum semiovale FA correlated (r = 0.36 to 0.56; p < 0.02) with contemporaneous (age 83) scores on psychometric tests of nonverbal reasoning, working memory, executive function, and information processing efficiency. Centrum semiovale FA also correlated with IQ at age 11 (r = 0.37; p = 0.02). Controlling for IQ at age 11 and information processing at age 83 attenuated the association between centrum semiovale FA and general cognitive ability by approximately 85%. MTR, largely, did not show significant correlations with cognitive test scores.

CONCLUSIONS

These data support the information processing efficiency hypothesis of cognitive aging and suggest one foundation for individual differences in processing efficiency. They also suggest that studies of imaging and cognition in the elderly should take into account prior mental ability rather than assuming that any associations between imaging parameters and cognitive test scores are the result of age-related changes.

Childhood IQ of parents related to characteristics of their offspring: linking the Scottish Mental Survey 1932 to the Midspan Family Study

The objective of the study was to investigate the relationship between childhood IQ of parents and characteristics of their adult offspring. It was a prospective family cohort study linked to a mental ability survey of the parents and set in Renfrew and Paisley in Scotland. Participants were 1921-born men and women who took part in the Scottish Mental Survey in 1932 and the Renfrew/Paisley study in the 1970s, and whose offspring took part in the Midspan Family study in 1996. There were 286 offspring from 179 families. Parental IQ was related to some, but not all characteristics of offspring. Greater parental IQ was associated with taller offspring. Parental IQ was inversely related to number of cigarettes smoked by offspring. Higher parental IQ was associated with better education, offspring social class and offspring deprivation category. There were no significant relationships between parental IQ and offspring systolic blood pressure, diastolic blood pressure, cholesterol, glucose, lung function, weight, body mass index, waist hip ratio, housing, alcohol consumption, marital status, car use and exercise. Structural equation modelling showed parental IQ associated with offspring education directly and mediated via parental social class. Offspring education was associated with offspring smoking and social class. The smoking finding may have implications for targeting of health education.

Association between genotype at an exonic SNP in DISC1 and normal cognitive aging

DISC1 is expressed in the hippocampus and has been identified as a possible genetic risk factor for both schizophrenia and bipolar disorder. These psychiatric illnesses are associated with impaired learning and memory. This study investigates the association of variation in DISC1 with cognitive function on the same general mental ability test (Moray House Test) at age 11 and age 79, and cognitive change between ages 11 and 79, in 425 people from the Lothian Birth Cohort 1921 (LBC1921). Tests of memory, non-verbal reasoning and executive function were also administered at age 79. The effect of genotype at a non-synonymous single nucleotide polymorphism in exon 11, rs821616, was studied. There was no direct effect of DISC1 genotype on any cognitive measure. However, there was a significant DISC1 genotype by sex interaction on Moray House Test scores at age 79, both before and after adjustment for cognitive ability at age 11 (p = 0.034 and 0.043, respectively). Women homozygous for the Cys allele had significantly lower cognitive ability scores than men at age 79, p = 0.003. Variation in DISC1 may therefore affect cognitive aging especially in women.

Cognitive correlates of cerebral white matter lesions and water diffusion tensor parameters in community-dwelling older people

BACKGROUND

The biological basis of cognitive ageing is unknown. One underlying process might be disruption of white matter tracts connecting cortical regions. White matter lesions (WML) seen on structural MRI may disrupt cortical connections, but diffusion tensor MRI (DT-MRI) parameters - mean diffusivity (<D>) and fractional anisotropy (FA) - may reflect more subtle changes in white matter integrity. Here the relationships between WML load, DT-MRI parameters and cognition in a large cohort of elderly subjects with a very narrow age range were investigated.

METHODS

105 community-dwelling volunteers underwent MRI and neuropsychological assessment. Seventy-two (68.6%) were female, and their mean age was 78.4 (SD 1.5) years. Scans were rated for WML load. <D> and FA were measured from regions of interest in normal-appearing frontal and occipital white matter, and centrum semiovale.

RESULTS

<D> and FA differed significantly among the three brain regions studied (p << 0.01). <D> increased with age (r = 0.22 to 0.35, p < 0.03), and was negatively correlated with FA (r = -0.20 to -0.51, p < 0.05) in all three regions. There was a trend towards increased WML load correlating with poorer cognitive function, and this was statistically significant for the Mini-Mental State Examination (rho = -0.23, p = 0.02). <D> was generally negatively correlated with cognitive test score, and FA was positively correlated. This pattern was more consistent for <D> than for FA, and particularly for verbal fluency (<D>: r = -0.22 to -0.27, p < 0.03), which measures executive function.

CONCLUSIONS

DT-MRI parameters, in particular <D>, are sensitive to early ultrastructural changes underlying cognitive ageing. Executive function may be the cognitive domain most sensitive to age-related decline in white matter tract integrity.