Service and clinical impacts of reader bias in breast cancer screening: a retrospective study

OBJECTIVES

To determine factors influencing reader agreement in breast screening and investigate the relationship between agreement level and patient outcomes.

METHODS

Reader pair agreement for 83 265 sets of mammograms from the Scottish Breast Screening service (2015-2020) was evaluated using Cohen's kappa statistic. Each mammography examination was read by two readers, per routine screening practice, with the second initially blinded but able to choose to view the first reader's opinion. If the two readers disagreed, a third reader arbitrated. Variation in reader agreement was examined by: whether the reader acted as the first or second reader, reader experience, and recall, cancer detection and arbitration recall rate.

RESULTS

Readers' opinions varied by whether they acted as the first or second reader. Furthermore, reader 2 was more likely to agree with reader 1 if reader 1 was more experienced than they were, and less likely to agree if they themselves were more experienced than reader 1 (P < .001). Agreement was not significantly associated with cancer detection rate, overall recall rate or arbitration recall rates (P > .05). Lower agreement between readers led to a higher arbiter workload (P < .001).

CONCLUSIONS

In mammography screening, the second reader's opinion is influenced by the first reader's opinion, with the degree of influence dependent on the readers' relative experience levels.

ADVANCES IN KNOWLEDGE

While less-experienced readers relied on their more experienced reading partner, no adverse impact on service outcomes was observed. Allowing access to the first reader's opinion may benefit newly qualified readers, but reduces independent evaluation, which may lower cancer detection rates.

Brain PET and SPECT imaging and quantification: a survey of the current status in the UK

OBJECTIVES

With disease-modifying therapies in development for neurological disorders, quantitative brain imaging techniques become increasingly relevant for objective early diagnosis and assessment of response to treatment. The aim of this study was to evaluate the use of Brain SPECT and PET scans in the UK and explore drivers and barriers to using quantitative analysis through an online survey.

METHODS

A web-based survey with 27 questions was used to capture a snapshot of brain imaging in the UK. The survey included multiple-choice questions assessing the availability and use of quantification for DaTscan, Perfusion SPECT, FDG PET and Amyloid PET. The survey results were reviewed and interpreted by a panel of imaging experts.

RESULTS

Forty-six unique responses were collected and analysed, with 84% of responses from brain imaging sites. Within these sites, 88% perform DaTscan, 50% Perfusion SPECT, 48% FDG PET, and 33% Amyloid PET, while a few sites use other PET tracers. Quantitative Brain analysis is used in 86% of sites performing DaTscans, 40% for Perfusion SPECT, 63% for FDG PET and 42% for Amyloid PET. Commercial tools are used more frequently than in-house software.

CONCLUSION

The survey showed variations across the UK, with high availability of DaTscan imaging and quantification and lower availability of other SPECT and PET scans. The main drivers for quantification were improved reporting confidence and diagnostic accuracy, while the main barriers were a perception of a need for an appropriate database of healthy controls and a lack of training, time, and software availability.

Impact of Different Mammography Systems on Artificial Intelligence Performance in Breast Cancer Screening

Artificial intelligence (AI) tools may assist breast screening mammography programs, but limited evidence supports their generalizability to new settings. This retrospective study used a 3-year dataset (April 1, 2016-March 31, 2019) from a U.K. regional screening program. The performance of a commercially available breast screening AI algorithm was assessed with a prespecified and site-specific decision threshold to evaluate whether its performance was transferable to a new clinical site. The dataset consisted of women (aged approximately 50-70 years) who attended routine screening, excluding self-referrals, those with complex physical requirements, those who had undergone a previous mastectomy, and those who underwent screening that had technical recalls or did not have the four standard image views. In total, 55 916 screening attendees (mean age, 60 years ± 6 [SD]) met the inclusion criteria. The prespecified threshold resulted in high recall rates (48.3%, 21 929 of 45 444), which reduced to 13.0% (5896 of 45 444) following threshold calibration, closer to the observed service level (5.0%, 2774 of 55 916). Recall rates also increased approximately threefold following a software upgrade on the mammography equipment, requiring per-software version thresholds. Using software-specific thresholds, the AI algorithm would have recalled 277 of 303 (91.4%) screen-detected cancers and 47 of 138 (34.1%) interval cancers. AI performance and thresholds should be validated for new clinical settings before deployment, while quality assurance systems should monitor AI performance for consistency. Keywords: Breast, Screening, Mammography, Computer Applications-Detection/Diagnosis, Neoplasms-Primary, Technology Assessment Supplemental material is available for this article. © RSNA, 2023.

Degeneration of basal and limbic networks is a core feature of behavioural variant frontotemporal dementia

The behavioural variant of frontotemporal dementia is a clinical syndrome characterized by changes in behaviour, cognition and functional ability. Although atrophy in frontal and temporal regions would appear to be a defining feature, neuroimaging studies have identified volumetric differences distributed across large parts of the cortex, giving rise to a classification into distinct neuroanatomical subtypes. Here, we extended these neuroimaging studies to examine how distributed patterns of cortical atrophy map onto brain network hubs. We used baseline structural magnetic resonance imaging data collected from 213 behavioural variant of frontotemporal dementia patients meeting consensus diagnostic criteria and having definite evidence of frontal and/or temporal lobe atrophy from a global clinical trial conducted in 70 sites in Canada, United States of America, Australia, Asia and Europe. These were compared with data from 244 healthy elderly subjects from a well-characterized cohort study. We have used statistical methods of hierarchical agglomerative clustering of 68 regional cortical and subcortical volumes (34 in each hemisphere) to determine the reproducibility of previously described neuroanatomical subtypes in a global study. We have also attempted to link the structural findings to clinical features defined systematically using well-validated clinical scales (Addenbrooke’s Cognitive Examination Revised, the Mini-Mental Status Examination, the Frontotemporal Dementia Rating Scale and the Functional Assessment Questionnaire) and subscales derived from them. Whilst we can confirm that the subtypes are robust, they have limited value in explaining the clinical heterogeneity of the syndrome. We have found that a common pattern of degeneration affecting a small number of subcortical, limbic and frontal nodes within highly connected networks (most previously identified as rich club members or functional binding nodes) is shared by all the anatomical subtypes. Degeneration in these core regions is correlated with cognitive and functional impairment, but less so with behavioural impairment. These findings suggest that degeneration in highly connected basal, limbic and frontal networks is a core feature of the behavioural variant of frontotemporal dementia phenotype irrespective of neuroanatomical and clinical heterogeneity, and may underly the impairment of integration in cognition, function and behaviour responsible for the loss of insight that characterizes the syndrome.

Long-Term Hydromethylthionine Treatment Is Associated with Delayed Clinical Onset and Slowing of Cerebral Atrophy in a Pre-Symptomatic P301S MAPT Mutation Carrier

One of the mutations in the microtubule-associated protein tau, P301S, is causative for dominantly inherited frontotemporal dementia characterized by extensive tau pathology for which no licensed treatment is available. Hydromethylthionine is a potent tau aggregation inhibitor. We report treatment of an asymptomatic carrier of the P301S mutation using hydromethylthionine over a 5-year period beginning at the mean age of onset of clinical decline in the family. During the period of treatment, the rates of progression of cerebral atrophy were reduced by 61%–66% in frontal and temporal lobes, and the patient remained clinically asymptomatic.

Concentration-Dependent Activity of Hydromethylthionine on Clinical Decline and Brain Atrophy in a Randomized Controlled Trial in Behavioral Variant Frontotemporal Dementia

BACKGROUND

Hydromethylthionine is a potent inhibitor of pathological aggregation of tau and TDP-43 proteins.

OBJECTIVE

To compare hydromethylthionine treatment effects at two doses and to determine how drug exposure is related to treatment response in bvFTD.

METHODS

We undertook a 52-week Phase III study in 220 bvFTD patients randomized to compare hydromethylthionine at 200 mg/day and 8 mg/day (intended as a control). The principal outcomes were change on the Addenbrookes Cognitive Examination - Revised (ACE-R), the Functional Activities Questionnaire (FAQ), and whole brain volume. Secondary outcomes included Modified Clinical Global Impression of Change (Modified-CGIC). A population pharmacokinetic exposure-response analysis was undertaken in 175 of the patients with available blood samples and outcome data using a discriminatory plasma assay for the parent drug.

RESULTS

There were no significant differences between the two doses as randomized. There were steep concentration-response relationships for plasma levels in the range 0.3-0.6 ng/ml at the 8 mg/day dose on clinical and MRI outcomes. There were significant exposure-dependent differences at 8 mg/day for FAQ, Modified-CGIC, and whole brain atrophy comparing patients with plasma levels greater than 0.346 ng/ml with having minimal drug exposure. The exposure-response is biphasic with worse outcomes at the high concentrations produced by 200 mg/day.

CONCLUSIONS

Hydromethylthionine has a similar concentration-response profile for effects on clinical decline and brain atrophy at the 8 mg/day dose in bvFTD as recently reported in AD. Treatment responses in bvFTD are predicted to be maximal at doses in the range 20-60 mg/day. A confirmatory placebo-controlled trial is now planned.

What are the earlier life contributions to reserve and resilience?

The brain's structures and functions arise from a combination of developmental processes and interaction with environmental experiences, beginning in utero and continuing throughout the lifespan. Broadly, the process that we think of as "successful aging" likely has its foundation in early life and is continuously shaped as life experiences are programmed into the brain in response to a changing environment. Thus, individual lifestyle choices and interventions aimed at increasing cognitive reserve and resilience could change the course of cognitive aging. To determine the relative efficacy of these approaches, we will need to understand how the timing of these interventions (e.g., age, duration, frequency) influences cognitive capacity through the lifespan. Although analysis of age-related changes in cognitive function reveals a general decline at the population level, it has become clear that there is great individual variance in the extent to which cognitive function changes with advanced age. The factors responsible for the individual differences in cognitive decline are unclear, but uncovering them with new analytical tools, epigenetic approaches, and subpopulation studies will provide a roadmap toward enhancing reserve and resilience in the population at large and preserving cognitive function in a greater number of aging individuals.

Motion During Acquisition is Associated With fMRI Brain Entropy

Measures of fMRI brain entropy have been used to investigate age and disease related neural changes. However, it is unclear if movement in the scanner is associated with brain entropy after geometric correction for movement. As age and disease can affect motor control, quantifying and correcting for the influence of movement will avoid false findings. This paper examines the influence of head motion on fMRI brain entropy. Resting-state and task-based fMRI data from 281 individuals born in Aberdeen between 1950 and 1956 were analyzed. The images were realigned, followed by nuisance regression of the head motion parameters. The images were either high-pass filtered (0.008 Hz) or band-pass (0.008-0.1 Hz) filtered in order to compare the two methods; fuzzy approximate entropy and fuzzy sample entropy were calculated for every voxel. Motion was quantified as the mean displacement and mean rotation in three dimensions. Greater mean motion was correlated with decreased entropy for all four methods of calculating entropy. Different movement characteristics produce different patterns of associations, which appear to be artefact. However, across all motion metrics, entropy calculation methods, and scan conditions, a number of regions consistently show a significant negative association: the right cerebellar crus, left precentral gyrus (primary motor cortex), the left postcentral gyrus (primary somatosensory cortex), and the opercular part of the left inferior frontal gyrus. The robustness of our findings at these locations suggests that decreased entropy in specific brain regions may be a marker for decreased motor control.

Concentration-Dependent Activity of Hydromethylthionine on Cognitive Decline and Brain Atrophy in Mild to Moderate Alzheimer's Disease

BACKGROUND

Although hydromethylthionine is a potent tau aggregation inhibitor, no difference was found in either of two Phase III trials in mild to moderate Alzheimer's disease (AD) comparing doses in the range 150-250 mg/day with 8 mg/day intended as a control.

OBJECTIVE

To determine how drug exposure is related to treatment response.

METHODS

A sensitive plasma assay for the drug was used in a population pharmacokinetic analysis of samples from 1,162 of the 1,686 patients who participated in either of the Phase III trials with available samples and efficacy outcome data.

RESULTS

There are steep concentration-response relationships for steady state plasma levels in the range 0.3-0.8 ng/ml at the 8 mg/day dose. Using a threshold based on the lower limit of quantitation of the assay on Day 1, there are highly significant differences in cognitive decline and brain atrophy in patients with above threshold plasma levels, both for monotherapy and add-on therapy, but with effect sizes reduced by half as add-on. Plasma concentrations in the range 4-21 ng/ml produced by the high doses are not associated with any additional benefit.

CONCLUSIONS

Hydromethylthionine has pharmacological activity on brain structure and function at the 8 mg/day dose as monotherapy or as add-on to symptomatic treatments. This combined with a plateau at higher doses is consistent with the lack of dose-response seen in the Phase III trials. Treatment benefit is predicted to be maximal at 16 mg/day as monotherapy. A placebo-controlled trial in mild/moderate AD is now ongoing to confirm efficacy at this dose.

Intellectual engagement and cognitive ability in later life (the "use it or lose it" conjecture): longitudinal, prospective study

OBJECTIVES

To examine the association between intellectual engagement and cognitive ability in later life, and determine whether the maintenance of intellectual engagement will offset age related cognitive decline.

DESIGN

Longitudinal, prospective, observational study.

SETTING

Non-clinical volunteers in late middle age (all born in 1936) living independently in northeast Scotland.

PARTICIPANTS

Sample of 498 volunteers who had taken part in the Scottish Mental Health Survey of 1947, from one birth year (1936).

MAIN OUTCOME MEASURES

Cognitive ability and trajectory of cognitive decline in later life. Typical intellectual engagement was measured by a questionnaire, and repeated cognitive measurements of information processing speed and verbal memory were obtained over a 15 year period (recording more than 1200 longitudinal data points for each cognitive test).

RESULTS

Intellectual engagement was significantly associated with level of cognitive performance in later life, with each point on a 24 point scale accounting for 0.97 standardised cognitive performance (IQ-like) score, for processing speed and 0.71 points for memory (both P<0.05). Engagement in problem solving activities had the largest association with life course cognitive gains, with each point accounting for 0.43 standardised cognitive performance score, for processing speed and 0.36 points for memory (both P<0.05). However, engagement did not influence the trajectory of age related decline in cognitive performance. Engagement in intellectual stimulating activities was associated with early life ability, with correlations between engagement and childhood ability and education being 0.35 and 0.22, respectively (both P<0.01).

CONCLUSION

These results show that self reported engagement is not associated with the trajectory of cognitive decline in late life, but is associated with the acquisition of ability during the life course. Overall, findings suggest that high performing adults engage and those that engage more being protected from relative decline.

Cortical Thickness and Surface Area Networks in Healthy Aging, Alzheimer's Disease and Behavioral Variant Fronto-Temporal Dementia

Models of the human brain as a complex network of inter-connected sub-units are important in helping to understand the structural basis of the clinical features of neurodegenerative disorders. The aim of this study was to characterize in a systematic manner the differences in the structural correlation networks in cortical thickness (CT) and surface area (SA) in Alzheimer's disease (AD) and behavioral variant Fronto-Temporal Dementia (bvFTD). We have used the baseline magnetic resonance imaging (MRI) data available from a large population of patients from three clinical trials in mild to moderate AD and mild bvFTD and compared this to a well-characterized healthy aging cohort. The study population comprised 202 healthy elderly subjects, 213 with bvFTD and 213 with AD. We report that both CT and SA network architecture can be described in terms of highly correlated networks whose positive and inverse links map onto the intrinsic modular organization of the four cortical lobes. The topology of the disturbance in structural network is different in the two disease conditions, and both are different from normal aging. The changes from normal are global in character and are not restricted to fronto-temporal and temporo-parietal lobes, respectively, in bvFTD and AD, and indicate an increase in both global correlational strength and in particular nonhomologous inter-lobar connectivity defined by inverse correlations. These inverse correlations appear to be adaptive in character, reflecting coordinated increases in CT and SA that may compensate for corresponding impairment in functionally linked nodes. The effects were more pronounced in the cortical thickness atrophy network in bvFTD and in the surface area network in AD. Although lobar modularity is preserved in the context of neurodegenerative disease, the hub-like organization of networks differs both from normal and between the two forms of dementia. This implies that hubs may be secondary features of the connectivity adaptation to neurodegeneration and may not be an intrinsic property of the brain. However, analysis of the topological differences in hub-like organization CT and SA networks, and their underlying positive and negative correlations, may provide a basis for assisting in the differential diagnosis of bvFTD and AD.

The influence of childhood intelligence, social class, education and social mobility on memory and memory decline in late life

In an observational longitudinal study of a sub-sample of the Aberdeen 1936 birth cohort, from age 62 to 77 years, we investigated childhood intelligence, social class, education, life-course social mobility, memory test performance and memory decline in late life. We examined 388 local residents who had attended school in Aberdeen in 1947 and measured Auditory-Verbal Learning Test (AVLT) at recruitment age about 64 years and up to five times until age about 77 years. Better performance at age about 64 on AVLT was predicted by early socioeconomic status (SES), social mobility and childhood intelligence. The trajectory of AVLT decline was steeper in those who had received less education. This relationship was independent of childhood ability, sex, SES in childhood and social mobility. The protection of memory by education suggests that education supports resilience to age-related cognitive impairment. Upward social mobility does not enhance this effect, suggesting that resilience to age-related decline may be established in early life.

Potential of Low Dose Leuco-Methylthioninium Bis(Hydromethanesulphonate) (LMTM) Monotherapy for Treatment of Mild Alzheimer's Disease: Cohort Analysis as Modified Primary Outcome in a Phase III Clinical Trial

Background:

LMTM is being developed as a treatment for AD based on inhibition of tau aggregation.

Objectives:

To examine the efficacy of LMTM as monotherapy in non-randomized cohort analyses as modified primary outcomes in an 18-month Phase III trial in mild AD.

Methods:

Mild AD patients (n = 800) were randomly assigned to 100 mg twice a day or 4 mg twice a day. Prior to unblinding, the Statistical Analysis Plan was revised to compare the 100 mg twice a day as monotherapy subgroup (n = 79) versus 4 mg twice a day as randomized (n = 396), and 4 mg twice a day as monotherapy (n = 76) versus 4 mg twice a day as add-on therapy (n = 297), with strong control of family-wise type I error.

Results:

The revised analyses were statistically significant at the required threshold of p < 0.025 in both comparisons for change in ADAS-cog, ADCS-ADL, MRI atrophy, and glucose uptake. The brain atrophy rate was initially typical of mild AD in both add-on and monotherapy groups, but after 9 months of treatment, the rate in monotherapy patients declined significantly to that reported for normal elderly controls. Differences in severity or diagnosis at baseline between monotherapy and add-on patients did not account for significant differences in favor of monotherapy.

Conclusions:

The results are consistent with earlier studies in supporting the hypothesis that LMTM might be effective as monotherapy and that 4 mg twice a day may serve as well as higher doses. A further suitably randomized trial is required to test this hypothesis.

A comparison of measurement methods of hippocampal atrophy rate for predicting Alzheimer's dementia in the Aberdeen Birth Cohort of 1936

INTRODUCTION

Various methods are available to measure hippocampal atrophy rate. We compared methods to predict Alzheimer's dementia.

METHODS

Participants with brain imaging at ages 69 and 73 years were identified from a previous study. Simple manual measures and computationally automated volumetry were performed. Receiver operating characteristics assessed the predictive ability of each method at baseline and on logit regression analysis of two serial scans.

RESULTS

Ten of 149 participants developed Alzheimer's dementia and had lower baseline volumes (3647 vs. 4194 mm3P = .002), rates of volume loss (-126 vs. -36 mm3/y; P = .001), and rates of loss in hippocampal fraction (-8.55 vs. -2.35 x 10-5/y; P = .001). Baseline volume with a rate of change gave the highest area under the curve value of 0.96.

DISCUSSION

Automated volumetry measuring hippocampal size at age 69 years and subsequent rate of change predicts Alzheimer's dementia development.

Efficacy and safety of tau-aggregation inhibitor therapy in patients with mild or moderate Alzheimer's disease: a randomised, controlled, double-blind, parallel-arm, phase 3 trial

BACKGROUND

Leuco-methylthioninium bis(hydromethanesulfonate; LMTM), a stable reduced form of the methylthioninium moiety, acts as a selective inhibitor of tau protein aggregation both in vitro and in transgenic mouse models. Methylthioninium chloride has previously shown potential efficacy as monotherapy in patients with Alzheimer's disease. We aimed to determine whether LMTM was safe and effective in modifying disease progression in patients with mild to moderate Alzheimer's disease.

METHODS

We did a 15-month, randomised, controlled double-blind, parallel-group trial at 115 academic centres and private research clinics in 16 countries in Europe, North America, Asia, and Russia with patients younger than 90 years with mild to moderate Alzheimer's disease. Patients concomitantly using other medicines for Alzheimer's disease were permitted to be included because we considered it infeasible not to allow their inclusion; however, patients using medicines carrying warnings of methaemoglobinaemia were excluded because the oxidised form of methylthioninium in high doses has been shown to induce this condition. We randomly assigned participants (3:3:4) to 75 mg LMTM twice a day, 125 mg LMTM twice a day, or control (4 mg LMTM twice a day to maintain blinding with respect to urine or faecal discolouration) administered as oral tablets. We did the randomisation with an interactive web response system using 600 blocks of length ten, and stratified patients by severity of disease, global region, whether they were concomitantly using Alzheimer's disease-labelled medications, and site PET capability. Participants, their study partners (generally carers), and all assessors were masked to treatment assignment throughout the study. The coprimary outcomes were progression on the Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog) and the Alzheimer's Disease Co-operative Study-Activities of Daily Living Inventory (ADCS-ADL) scales from baseline assessed at week 65 in the modified intention-to-treat population. This trial is registered with Clinicaltrials.gov (NCT01689246) and the European Union Clinical Trials Registry (2012-002866-11).

FINDINGS

Between Jan 29, 2013, and June 26, 2014, we recruited and randomly assigned 891 participants to treatment (357 to control, 268 to 75 mg LMTM twice a day, and 266 to 125 mg LMTM twice a day). The prespecified primary analyses did not show any treatment benefit at either of the doses tested for the coprimary outcomes (change in ADAS-Cog score compared with control [n=354, 6·32, 95% CI 5·31-7·34]: 75 mg LMTM twice a day [n=257] -0·02, -1·60 to 1·56, p=0·9834, 125 mg LMTM twice a day [n=250] -0·43, -2·06 to 1·20, p=0·9323; change in ADCS-ADL score compared with control [-8·22, 95% CI -9·63 to -6·82]: 75 mg LMTM twice a day -0·93, -3·12 to 1·26, p=0·8659; 125 mg LMTM twice a day -0·34, -2·61 to 1·93, p=0·9479). Gastrointestinal and urinary effects were the most common adverse events with both high doses of LMTM, and the most common causes for discontinuation. Non-clinically significant dose-dependent reductions in haemoglobin concentrations were the most common laboratory abnormality. Amyloid-related imaging abnormalities were noted in less than 1% (8/885) of participants.

INTERPRETATION

The primary analysis for this study was negative, and the results do not suggest benefit of LMTM as an add-on treatment for patients with mild to moderate Alzheimer's disease. Findings from a recently completed 18-month trial of patients with mild Alzheimer's disease will be reported soon.

FUNDING

TauRx Therapeutics.

Late-life deficits in cognitive, physical and emotional functions, childhood intelligence and occupational profile: a life-course examination of the Aberdeen 1936 Birth Cohort (ABC1936)

OBJECTIVES

the 'triad of impairment' phenomenon describes the co-occurrence of age-related cognitive, emotional and physical functioning deficits. We investigated how occupational profile and childhood intelligence contribute to the triad of impairment in late life.

METHODS

we analysed data of a subsample of the Aberdeen Birth Cohort of 1936 (n = 346). Data were collected on participants' childhood intelligence, late-life cognitive ability, physical functioning, depressive symptoms and main lifetime occupation. We summarised the various occupational and impairment measures into two latent variables, 'occupational profile' and the 'triad of impairment'. We used a series of data reduction approaches and structural equation models (SEMs) of increasing complexity to test both the validity of the models and to understand causal relationships between the life-course risks for the triad of impairment.

RESULTS

occupational profile had a significant effect on the triad of impairment independent of childhood intelligence. Childhood intelligence was the predominant influence on the triad of impairment and exerted its effect directly and indirectly via its influence on occupation. The direct effect of childhood intelligence exceeded the independent influence of the occupational profile on impairment by a factor of 1.7-1.8 and was greater by a factor of ∼4 from the indirect pathway (via occupation).

CONCLUSIONS

childhood intelligence was the predominant influence on the triad of impairment in late life, independently of the occupational profile. Efforts to reduce impairment in older adults should be informed by a life-course approach with special attention to the early-life environment.

Cerebral correlates of cognitive reserve

Cognitive reserve is a hypothetical concept introduced to explain discrepancies between severity of clinical dementia syndromes and the extent of dementia pathology. We examined cognitive reserve in a research programme that followed up a non-clinical sample born in 1921 or 1936 and IQ-tested age 11 years in 1932 or 1947. Structural MRI exams were acquired in about 50% of the sample from whom a subsample were recruited into an additional fMRI study. Here, we summarise findings from seven inter-related studies. These support an understanding of cognitive reserve as a balance between positive life course activity-driven experiences and the negative effects of brain pathologies including cerebrovascular disease and total and regional brain volume loss. Hypothesised structural equation models illustrate the relative causal effects of these positive and negative contributions. Cognitive reserve is considered in the context of choice of interventions to prevent dementia and the opposing effects of cerebrovascular disease and Alzheimer like brain appearances.

A brain imaging repository of normal structural MRI across the life course: Brain Images of Normal Subjects (BRAINS)

The Brain Images of Normal Subjects (BRAINS) Imagebank (http://www.brainsimagebank.ac.uk) is an integrated repository project hosted by the University of Edinburgh and sponsored by the Scottish Imaging Network: A Platform for Scientific Excellence (SINAPSE) collaborators. BRAINS provide sharing and archiving of detailed normal human brain imaging and relevant phenotypic data already collected in studies of healthy volunteers across the life-course. It particularly focusses on the extremes of age (currently older age, and in future perinatal) where variability is largest, and which are under-represented in existing databanks. BRAINS is a living imagebank where new data will be added when available. Currently BRAINS contains data from 808 healthy volunteers, from 15 to 81years of age, from 7 projects in 3 centres. Additional completed and ongoing studies of normal individuals from 1st to 10th decades are in preparation and will be included as they become available. BRAINS holds several MRI structural sequences, including T1, T2, T2* and fluid attenuated inversion recovery (FLAIR), available in DICOM (http://dicom.nema.org/); in future Diffusion Tensor Imaging (DTI) will be added where available. Images are linked to a wide range of 'textual data', such as age, medical history, physiological measures (e.g. blood pressure), medication use, cognitive ability, and perinatal information for pre/post-natal subjects. The imagebank can be searched to include or exclude ranges of these variables to create better estimates of 'what is normal' at different ages.

Tau aggregation inhibitor therapy: an exploratory phase 2 study in mild or moderate Alzheimer's disease

BACKGROUND

As tau aggregation pathology correlates with clinical dementia in Alzheimer's disease (AD), a tau aggregation inhibitor (TAI) could have therapeutic utility. Methylthioninium (MT) acts as a selective TAI in vitro and reduces tau pathology in transgenic mouse models.

OBJECTIVE

To determine the minimum safe and effective dose of MT required to prevent disease progression on clinical and functional molecular imaging outcomes.

METHODS

An exploratory double-blind, randomized, placebo-controlled, dose-finding trial of MT (69, 138, and 228 mg/day) was conducted in 321 mild/moderate AD subjects. The primary outcome was change on the Alzheimer's Disease Assessment Scale-cognitive subscale (ADAS-cog) at 24 weeks relative to baseline severity. Effect of treatment on regional cerebral blood flow decline was determined in a sub-study in 135 subjects. After 24 weeks, subjects were re-consented to enter sequential 6- and 12-month blinded extension phases. Registered with ClinicalTrials.gov (NCT00515333).

RESULTS

At 24 weeks, there were significant treatment benefits in two independent populations at the 138 mg/day dose: in moderate subjects on the ADAS-cog scale (treatment effect: -5.42 units, corrected p = 0.047) and two other clinical scales; in mild subjects on the more sensitive regional cerebral blood flow measure (treatment effect: 1.97%, corrected p < 0.001). With continued treatment for 50 weeks, benefit was seen on the ADAS-cog scale in both mild and moderate subjects. The delivery of the highest dose was impaired due to dose-dependent dissolution and absorption limitations.

CONCLUSION

The minimum safe and effective daily MT dose is 138 mg and suggests that further study of MT is warranted in AD.

Structural brain complexity and cognitive decline in late life--a longitudinal study in the Aberdeen 1936 Birth Cohort

Brain morphology and cognitive ability change with age. Gray and white matter volumes decrease markedly by the 7th decade of life when cognitive decreases first become readily detectable. As a consequence, the shape complexity of the cortical mantle may also change. The purposes of this study are to examine changes over a five year period in brain structural complexity in late life, and to investigate cognitive correlates of any changes. Brain magnetic resonance images at 1.5 Tesla were acquired from the Aberdeen 1936 Birth Cohort at about ages 68 years (243 participants) and 73 years (148 participants returned). Measures of brain complexity were extracted using Fractal Dimension (FD) and calculated using the box-counting method. White matter complexity, brain volumes and cognitive performance were measured at both 68 and 73 years. Childhood ability was measured at age 11 using the Moray House Test. FD and brain volume decrease significantly from age 68 to 73 years. Using a multilevel linear modeling approach, we conclude that individual decreases in late life white matter complexity are not associated with differences in executive function but are linked to information processing speed, auditory-verbal learning, and reasoning in specific models-with adjustment for childhood mental ability. A significant association was found after adjustment for age, brain volume and childhood mental ability. Complexity of white matter is associated with higher fluid cognitive ability and, in a longitudinal study, predicts retention of cognitive ability within late life.

Nonlinear complexity analysis of brain FMRI signals in schizophrenia

We investigated the differences in brain fMRI signal complexity in patients with schizophrenia while performing the Cyberball social exclusion task, using measures of Sample entropy and Hurst exponent (H). 13 patients meeting diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM IV) criteria for schizophrenia and 16 healthy controls underwent fMRI scanning at 1.5 T. The fMRI data of both groups of participants were pre-processed, the entropy characterized and the Hurst exponent extracted. Whole brain entropy and H maps of the groups were generated and analysed. The results after adjusting for age and sex differences together show that patients with schizophrenia exhibited higher complexity than healthy controls, at mean whole brain and regional levels. Also, both Sample entropy and Hurst exponent agree that patients with schizophrenia have more complex fMRI signals than healthy controls. These results suggest that schizophrenia is associated with more complex signal patterns when compared to healthy controls, supporting the increase in complexity hypothesis, where system complexity increases with age or disease, and also consistent with the notion that schizophrenia is characterised by a dysregulation of the nonlinear dynamics of underlying neuronal systems.

Early life socioeconomic circumstance and late life brain hyperintensities--a population based cohort study

CONTEXT

There have been many reports confirming the association between lower childhood socioeconomic circumstance and cardiovascular disease but evidence for links with cerebrovascular disease is contradictory. Hyperintensities on brain magnetic resonance imaging are associated with vascular risk factors, cognitive decline, dementia and death. However, the relationship between childhood socioeconomic circumstance and these lesions is unclear.

OBJECTIVE

To test the hypothesis that childhood socioeconomic circumstance is associated with late life hyperintensity burden and that neither adult socioeconomic circumstance nor change in socioeconomic circumstance during life influence this effect.

DESIGN

Cohort study.

SETTING

Community.

PARTICIPANTS

227 community dwelling members of the 1936 Aberdeen Birth Cohort aged 68 years, who were free from dementia.

MAIN OUTCOME MEASURES

Relationship between early life socioeconomic circumstance (paternal occupation) and abundance of late life brain hyperintensities.

RESULTS

We find significant negative correlations between childhood socioeconomic circumstance and white matter hyperintensities (ρ = -0.18, P<0.01), and periventricular hyperintensities (ρ = -0.15, P<0.05), between educational attainment and white matter hyperintensities (ρ = -0.15, P<0.05) and periventricular hyperintensities (ρ = -0.17, P<0.05), and between childhood intelligence and periventricular hyperintensities (ρ = -0.14, P<0.05). The relationship is strongest for childhood socioeconomic circumstance and regional white matter hyperintensities, where there is a step change in increased burden from paternal occupation grades equivalent to a shift from "white collar" to "blue collar" paternal occupation. Significant correlations were also found between hypertension and hyperintensity burden in all brain regions (ρ = 0.15-0.24, P<0.05). In models that include hypertension, the magnitude of the effect of childhood socioeconomic circumstance is similar to and independent from that of hypertension.

CONCLUSIONS

Childhood socioeconomic circumstance predicts the burden of brain white matter hyperintensities aged 68 years. The mechanism underlying this effect is unknown, but may act through fetal and/or early life programming of cerebrovascular disease. Future work to understand this vulnerability will inform strategies to reduce dementia and stroke.

Genetic and environmental factors in late onset dementia: possible role for early parental death

OBJECTIVE

We aimed to investigate three reports of a possible role of early parental death in late onset dementia. We tested a multivariate model of risk factors for late onset dementia that included established (female sex, a family history of dementia, APOE ε4) and putative influences (vascular risk factors, years of full-time education, parental ages at death, and childhood IQ) on dementia risk.

METHODS

We examined contributions of early life and late life risk factors for dementia by using childhood social and family data and blood samples obtained at interview at age about 78 years. In 1997-1999, we recruited 281 subjects without dementia from a 1932 Scottish IQ survey of children born in 1921 and followed them up to 2010 (at age 88). Binary logistic regression and Bayesian structural equation modelling were used to model dementia risk.

RESULTS

Risk of dementia was associated with increasing age from 77 to 88 years, female sex, death of either parent before age 11 and APOE ε4 genotype. Family history of dementia, childhood IQ, years of education and vascular risk factors did not contribute to the model.

CONCLUSIONS

Our multivariate models of the possible causes of late onset dementia confirm previous associations of dementia with female sex and APOE ε4 genotype and supports earlier reports of a role for early parental death.

Depressive symptoms in late life and cerebrovascular disease: the importance of intelligence and lesion location

BACKGROUND

The influence of white matter lesions on depressive symptoms in healthy ageing populations remains unclear. In this study, we examined the relationship between depressive symptoms and magnetic resonance imaging (MRI) detected cerebrovascular disease in a normal population living independently in the community, and measured the influence of location of brain abnormalities, fluid intelligence, living alone, and sex.

METHODS

Prospective cohort: 497 community dwelling individuals all born in 1936, who took part in the Scottish Mental Survey of 1947, were followed up in 2000 and at biannual intervals in a longitudinal study of health and cognitive aging. Two hundred forty-four volunteered for brain MRI in 2004-2006. Suitable data were available in 219/244, of whom 115 were men. Brain hyperintensities in lobar white matter, basal ganglia , periventricular, and infratentorial regions were measured using Scheltens' scale. Depressed mood was assessed using the Hospital Anxiety and Depression Scale (HADS) on three biannual intervals. Relationships between Scheltens' scores, HADS-D scores, fluid intelligence, living alone, and sex were assessed using general linear modeling.

RESULTS

The main predictor of depressive symptom scores was poorer fluid intelligence (partial η(2) =0.023-0.028, P < .05). Ischemic change in the brainstem (partial η(2) = 0.026, P ≤.05) and basal ganglia (partial η(2) =0.018, P ≤ .05) also predicted HADS-D scores. There was no relationship with sex or living alone.

CONCLUSIONS

Hyperintensities in the brainstem and basal ganglia are associated with depressive symptoms. Higher fluid intelligence is associated with lower depressive symptoms in this normal, ageing population.

Openness to experience and activity engagement facilitate the maintenance of verbal ability in older adults

The current study used data from the Aberdeen Birth Cohort, 1936, to investigate the hypothesis that the positive effects of the personality trait Openness on cognitive ability are mediated by activity levels. Results of latent growth modeling analysis revealed that higher Openness predicted better reading ability, inductive reasoning, and memory performance across three testing occasions when participants were aged 64-68 years. Higher Openness predicted higher activity levels, and higher activity levels in turn predicted higher reading ability, but not higher performance on measures of inductive reasoning, memory, and speed of processing. Overall, Openness and activity engagement appear related to preserved higher cognitive ability in older adults, with Openness having a direct effect on marker tests of fluid ability and with the combined influence of Openness and activity being particularly important for marker tests of crystallized intelligence.

Childhood socioeconomic status and adult brain size: childhood socioeconomic status influences adult hippocampal size

OBJECTIVE

To investigate in older adults without dementia the relationships between socioeconomic status (SES) in childhood and magnetic resonance imaging (MRI)-derived brain volume measures typical of brain aging and Alzheimer's disease (AD).

METHODS

Using a cross-sectional and longitudinal observation approach, we invited volunteers without dementia, all born in 1936, and who were participants in the 1947 Scottish Mental Survey, for MR brain imaging; 249 of 320 (77%) agreed. We measured whole brain and hippocampal volumes and recorded childhood SES history, the number of years of education undertaken, and adult SES history. Mental ability at age 11 years was recorded in 1947 and was also available.

RESULTS

Analysis shows a significant association between childhood SES and hippocampal volume after adjusting for mental ability at age 11 years, adult SES, gender, and education.

INTERPRETATION

A significant association between childhood SES and hippocampal volumes in late life is consistent with the established neurodevelopmental findings that early life conditions have an effect on structural brain development. This remains detectable more than 50 years later.

Brain lesions, hypertension and cognitive ageing in the 1921 and 1936 Aberdeen birth cohorts

The objectives of this study are to model the relative effects of positive (childhood intelligence) and negative (magnetic resonance imaging (MRI)-derived white matter hyperintensities (WMH)) predictors of late-life intelligence in two well-characterised normal cohorts aged 68 and 78 and to measure the influence of hypertension on WMH and lifelong cognitive change. The Scottish Mental Surveys of 1932 and 1947 tested the intelligence of almost all school children at age 11. One hundred and one participants born in 1921 and 233 participants born in 1936 had brain MRI, with measurement of WMH using Scheltens' scale, and tests of late-life fluid intelligence. Structural equation models of the effect of childhood intelligence and brain WMH on the general intelligence factor 'g' in late life in the two samples were constructed using AMOS 18. Similar models were constructed to test the effect of hypertension on WMH and lifelong cognitive change. Fluid intelligence scores were lower and WMH scores were higher in the older samples. Hypertensive participants in both samples had more WMH than normotensive participants. The positive influence of childhood intelligence on 'g' was greater in the younger sample. The negative effect of WMH on 'g' was linear and greater in the older sample due to greater WMH burden. The negative effect of hypertension on lifelong cognitive ageing was all mediated via MRI-derived brain WMH. The positive relationship between childhood and late-life intelligence decreases with age. The negative relationship between WMH and late-life intelligence is linear and increases with age.

Do brain image databanks support understanding of normal ageing brain structure? A systematic review

OBJECTIVE

To document accessible magnetic resonance (MR) brain images, metadata and statistical results from normal older subjects that may be used to improve diagnoses of dementia.

METHODS

We systematically reviewed published brain image databanks (print literature and Internet) concerned with normal ageing brain structure.

RESULTS

From nine eligible databanks, there appeared to be 944 normal subjects aged ≥60 years. However, many subjects were in more than one databank and not all were fully representative of normal ageing clinical characteristics. Therefore, there were approximately 343 subjects aged ≥60 years with metadata representative of normal ageing, but only 98 subjects were openly accessible. No databank had the range of MR image sequences, e.g. T2*, fluid-attenuated inversion recovery (FLAIR), required to effectively characterise the features of brain ageing. No databank supported random subject retrieval; therefore, manual selection bias and errors may occur in studies that use these subjects as controls. Finally, no databank stored results from statistical analyses of its brain image and metadata that may be validated with analyses of further data.

CONCLUSION

Brain image databanks require open access, more subjects, metadata, MR image sequences, searchability and statistical results to improve understanding of normal ageing brain structure and diagnoses of dementia.

KEY POINTS

• We reviewed databanks with structural MR brain images of normal older people. • Among these nine databanks, 98 normal subjects ≥60 years were openly accessible. • None had all the required sequences, random subject retrieval or statistical results. • More access, subjects, sequences, metadata, searchability and results are needed. • These may improve understanding of normal brain ageing and diagnoses of dementia.

Childhood intelligence and brain white matter hyperintensities predict fluid intelligence age 78-81 years: a 1921 Aberdeen birth cohort study

OBJECTIVES

to evaluate the role of childhood intelligence and white matter hyperintensities (WMH) in the prediction of the trajectory of fluid intelligence in healthy old people from age 78 to 81.

DESIGN

observational follow-up study from 1999 to 2002.

SETTING

a university teaching hospital in Aberdeen, UK.

PARTICIPANTS

a total of 106 volunteers born in 1921, with childhood intelligence records at 11, recruited 1997-98 to a follow-up study.

MEASUREMENTS

participants underwent brain MRI in 1999-2000, to obtain measurements of brain WMH using Scheltens' scale and a test of fluid intelligence (Raven's Progressive Matrices) on three occasions between 1999 and 2002.

RESULTS

in a latent growth model, we found a significant association between childhood intelligence and the intercept, but not the slope, of fluid cognitive ability in late adulthood. Similarly, baseline WMH score was associated with the intercept of late life cognitive ability, but not the slope. Age at imaging was associated with slope but not intercept. There was no significant association between sex and intercept or slope of late life cognitive ability.

CONCLUSIONS

results suggest that brain MRI measures of WMH (attributed to cerebrovascular disease) and childhood intelligence significantly contribute to late life fluid cognitive ability but not to the trajectory of age-related change in fluid intelligence. We also show that age is associated with the cognitive trajectory from 78 to 81 years, even within our narrow age range sample. This may be a consequence of the recruitment pattern, with those having greater WMH burden, and who subsequently declined, being recruited later in the study.

Inter-individual differences in fMRI entropy measurements in old age

We investigated the association between individual differences in cognitive performance in old age and the approximate entropy (ApEn) measured from functional magnetic resonance imaging (fMRI) data acquired from 40 participants of the Aberdeen Birth Cohort 1936 (ABC1936), while undergoing a visual information processing task: inspection time (IT). Participants took a version of the Moray House Test (MHT) No. 12 at age 11, a valid measure of childhood intelligence. The same individuals completed a test of non-verbal reasoning (Raven's Standard Progressive Matrices [RPM]) aged about 68 years. The IT, MHT and RPM scores were used as indicators of cognitive performance. Our results show that higher regional signal entropy is associated with better cognitive performance. This finding was independent of ability in childhood but not independent of current cognitive ability. ApEn is used for the first time to identify a potential source of individual differences in cognitive ability using fMRI data.

How the 1932 and 1947 mental surveys of Aberdeen schoolchildren provide a framework to explore the childhood origins of late onset disease and disability

OBJECTIVES

To describe the discovery and development of the Aberdeen 1921 and 1936 birth cohort studies.

STUDY DESIGN

The Aberdeen birth cohort studies were started in 1998 when the Scottish Mental Survey archives of the Scottish Council for Research in Education were re-discovered and permissions granted to follow-up survivors born in 1921 or 1936 and then aged about 77 or 64 years and who had entered (or were about to enter) the age of greatest risk for Alzheimer's disease (AD).

MAIN OUTCOME MEASURES

Sources of attrition from the study, exposures to childhood adversity, nutritional, genetic and life style factors of possible relevance to extent of age-related cognitive decline and the timing of onset of dementia.

RESULTS

By 2010, the feasibility of following up more than 75% of Scottish Mental Survey survivors living in the Aberdeen area without dementia was well-established, dementia ascertainment to age about 88 years was completed in the 1921 birth cohort and was underway in the 1936 born cohort.

CONCLUSION

These databases are available to other bone fide research groups wishing to test specific hypotheses that may either replicate their own findings or make best use of the data collected in the Aberdeen studies.

Regional cerebral blood flow and aberrant motor behaviour in Alzheimer's disease

Aberrant motor behaviour (AMB) in Alzheimer's disease shares behavioural correlates with obsessive compulsive disorder (OCD). We investigated whether AMB was also comparable in terms of metabolic activity in the orbitofrontal cortex (OFC), an area shown to be hyperactive in OCD. In this study 135 patients meeting research criteria for Alzheimer's disease were identified from a database of patients recruited as part of a phase II drug trial. These patients were assessed using the Neuropsychiatric Inventory, the Alzheimer's disease assessment scale, cognitive subscale and perfusion SPECT performed with 99Tc(m) hexamethylpropyleneamine oxime. Regions of interest were created for orbitofrontal cortices and basal ganglia. In 35 patients with AMB, adjusted tracer uptake was greater in the OFC. This reached statistical significance in right superior, left superior, right medial and left medial orbital gyri (p < 0.05). The association between AMB and hyperactivity in the OFC remained significant after adjusting for the presence of anxiety. These results parallel the OFC hypermetabolism consistently seen in OCD. One model of OCD, proposes that dysfunctional interactions between frontal regions, including the OFC, produce the characteristic symptoms of OCD. The behaviour is though to be brought about by a perceived incompleteness of performing a task and is caused by an error in normal reward signals initiated upon task completion. These finding indicate that AMB in Alzheimer's disease are brought about by the same mechanistic failure.

Brain volume and survival from age 78 to 85: the contribution of Alzheimer-type magnetic resonance imaging findings

OBJECTIVES

To test the prediction of survival using magnetic resonance imaging (MRI)-derived global and regional brain volumes in subjects aged 78 to 79 without dementia.

DESIGN

Observational follow-up study.

SETTING

University teaching hospital.

PARTICIPANTS

Participants born in 1921, recruited in 1997/98 to a longitudinal study, who underwent brain MRI in 1999/2000.

MEASUREMENTS

Vital status on May 12, 2006, global and regional brain volumes.

RESULTS

Thirty-seven of 98 (34.9%) participants died during follow-up. After adjustment for cognitive ability at time of MRI examination, childhood intelligence, sex, hypertension, smoking history, obesity, hyperlipidemia, and age at MRI, proportion of intracranial volume occupied by the brain (brain fraction) predicted death before age 85 (P=.04). Participants with brain fraction less than 0.726 had more than twice the relative risk (2.8, 95% confidence interval=1.1-7.3) of death than participants with brain fraction greater 0.726. Lower survival was significantly associated with lower gray matter volumes in bilateral parietal and left frontoparietal areas and with lower white matter volumes in left parietal and right posterior temporal regions. Cox regression analysis showed that parietal white matter volume (P=.003), a subsequent diagnosis of dementia (P<.001), and sex (P=.004) were independent predictors of survival.

CONCLUSION

In participants aged 78 to 79, a lower global brain fraction predicted survival to approximately age 85. Smaller regional volumetric brain reductions, seen in Alzheimer's disease (AD), also predicted survival independent of dementia. The presence of prodromal AD probably explain the main findings.

Is retaining the youthful functional anatomy underlying speed of information processing a signature of successful cognitive ageing? An event-related fMRI study of inspection time performance

It has been hypothesized that individual differences in cognitive ageing might in part be based on the relative preservation of speed of information processing. However, the biological foundations of processing speed are not understood. Here we compared two groups of non-demented older people who had relatively similar IQs at age 11 but differed markedly in non-verbal reasoning ability at age 70: 'cognitive sustainers' (n=25), and 'cognitive decliners' (n=15). Using an event-related fMRI design, we studied the BOLD response while they performed an inspection time task. Inspection time is a two-alternative forced choice, backward masking test of the speed of the early stages of visual information processing. Inspection time has a well-established, significant association with higher cognitive abilities. The group of cognitive sustainers showed a pattern of BOLD activation-deactivation in response to inspection time stimulus duration differences that was similar to a healthy young sample [Deary, I.J., Simonotto, E., Meyer, M., Marshall, A., Marshall, I., Goddard, N., Watdlaw, J.M., 2004a. The functional anatomy of inspection time: an event-related fMRI study. NeuroImage 22, 1466-1479]. The group of cognitive decliners lacked these clear neural networks. The relative preservation of complex reasoning skills in old age may be associated with the preservation of the neural networks that underpin fundamental information processing in youth.

Baseline MRI delivery characteristics predict change in invasive ductal breast carcinoma PET metabolism as a result of primary chemotherapy administration

BACKGROUND

The aim of the study was to investigate whether pre-therapy vascular delivery assessment [using dynamic contrast enhanced magnetic resonance imaging (DCE-MRI)] can predict reduction in breast cancer metabolism [detected using 2-[(18)F] fluoro-2-deoxy-D-glucose positron emission tomography ((18)F(-)FDG-PET)] after a single cycle of chemotherapy. Reduction in (18)F-FDG PET metabolism has previously been shown to correlate with histological response to primary chemotherapy.

PATIENTS AND METHODS

Seventeen patients with large or locally advanced invasive ductal carcinomas of the breast were imaged using DCE-MRI and (18)F-FDG-PET prior to therapy and 20 days after the first cycle of chemotherapy. MRI data were analysed using a multi-compartment model. PET data were analysed using standardised uptake value (SUV) analysis.

RESULTS

A significant association (P <0.05) was observed between pre-therapy DCE-MRI vascular parameters and the reduction in PET metabolism resulting from administration of one cycle of chemotherapy.

CONCLUSIONS

A relationship was demonstrated between pre-therapy DCE-MRI vascular parameters and the reduction in PET metabolism after a single cycle of chemotherapy. This suggests that reduction in PET metabolism as a result of chemotherapy may be dependent, at least in part, on pre-therapy vascular delivery. These pre-therapy vascular characteristics may be suitable for use as a surrogate measure for initial chemotherapy delivery, a key factor in chemotherapeutic efficacy.

Monitoring primary breast cancer throughout chemotherapy using FDG-PET

We have compared 2-deoxy-2-[(18)F]-fluoro-D-glucose positron emission tomography (FDG-PET) images of large or locally advanced breast cancers (LABC) acquired during Anthracycline-based chemotherapy. The purpose was to determine whether there is an optimal method for defining tumour volume and an optimal imaging time for predicting pathologic chemotherapy response.

METHOD

PET data were acquired before the first and second cycles, at the midpoint and at the endpoint of neoadjuvant chemotherapy. FDG uptake was quantified using the mean and maximum standardized uptake values (SUV) and the coefficient of variation within a region of interest. Receiver-operator characteristic (ROC) analysis was used to determine the discrimination between tumours demonstrating a high pathological response (i.e. those with greater than 90% reduction in viable tumour cells) and low pathological response.

RESULTS

Only tumours with an initial tumour to background ratio (TBR) of greater than five showed a difference between response categories. In terms of response discrimination, there was no statistically significant advantage of any of the methods used for image quantification or any of the time points. The best discrimination was measured for mean SUV at the midpoint of therapy, which identified 77% of low responding tumours whilst correctly identifying 100% of high responding tumours and had an ROC area of 0.93.

CONCLUSION

FDG-PET is efficacious for predicting the pathologic response of most primary breast tumours throughout the duration of a neoadjuvant chemotherapy regimen. However, this technique is ineffective for tumours with low image contrast on pre-therapy PET scans.

Generality and specificity in cognitive aging: a volumetric brain analysis

OBJECTIVE

To investigate whether, in old age, brain volume differences are associated with age-related change in general mental ability and/or specific cognitive abilities.

METHODS

The authors investigate the association between brain volumes and current cognitive function in a well-characterized sample of healthy old people (aged 79-80) whose intelligence was recorded at age 11. This allowed estimation of intellectual change over the life span.

RESULTS

After accounting for childhood intelligence, associations were found between specific cognitive measures and brain volumes. An association was also found between volumes and the general intelligence factor g. After removing the influence of g from each of the specific cognitive measures, no remaining significant associations were found between brain volumes and the specific part of each test.

CONCLUSIONS

Generalized cognitive aging is associated with brain volume differences, but there is no evidence in this sample that specific components of cognitive aging are associated with differences in brain volume.

Brain white matter hyperintensities: relative importance of vascular risk factors in nondemented elderly people

PURPOSE

To prospectively determine whether there is an association between brain white matter signal hyperintensities on magnetic resonance (MR) images and potential risk factors for cerebral ischemia in a well-characterized narrow age cohort of nondemented community-dwelling elderly people.

MATERIALS AND METHODS

The study population consisted of surviving members of the Aberdeen 1921 Birth Cohort, a subsample of participants in the 1932 Scottish Mental Survey who were born in 1921. With the permission of the local ethics committee and with informed written consent, 106 nondemented subjects (62 men, 44 women) aged 78-79 years underwent T2-weighted brain MR imaging. Brain MR images were scored semiquantitatively for deep white matter hyperintensities and periventricular hyperintensities. Vascular risk factors and clinical measures potentially associated with cerebral ischemia included hypertension, diabetes, cerebrovascular disease, smoking, body mass index grade, respiratory function levels (forced expiratory volume in 1 second [FEV1], forced vital capacity [FVC], and peak expiratory flow rate [PEFR]) normalized for subject's height, plasma lipid levels (cholesterol, triglycerides, high-density lipoprotein, and low-density lipoprotein), glycated hemoglobin level, and mean fasting blood glucose level. Pearson correlation coefficients were calculated for correlations between potential vascular risk factors and scores for deep white matter and periventricular hyperintensities, and stepwise multiple linear regression analysis was performed for factors with a statistically significant correlation.

RESULTS

Significant Pearson correlations with deep white matter hyperintensities were found for glycated hemoglobin level (r = 0.31), hypertension (r = 0.27), normalized FEV1 (r = -0.27), normalized FVC (r = -0.22), normalized PEFR (r = -0.27), low-density lipoprotein (r = 0.24), and cholesterol (r = 0.20), and with periventricular hyperintensities for glycated hemoglobin level (r = 0.28) and normalized PEFR (r = -0.23). Multiple linear regression analysis showed that glycated hemoglobin level and hypertension were predictive of 16.2% of the variance in deep white matter hyperintensities. When subjects with non-insulin-dependent (type 2) diabetes mellitus (n = 11) were excluded, hypertension and decreased normalized PEFR were predictive of 11.7% of the variance.

CONCLUSION

White matter hyperintensities are associated with elevated levels of glycated hemoglobin in nondemented community-dwelling elderly subjects. Hypertension and decreased normalized PEFR are the principal predictors of deep white matter hyperintensities in nondiabetic subjects.

The use of the Levenberg-Marquardt curve-fitting algorithm in pharmacokinetic modelling of DCE-MRI data

The use of curve-fitting and compartmental modelling for calculating physiological parameters from measured data has increased in popularity in recent years. Finding the 'best fit' of a model to data involves the minimization of a merit function. An example of a merit function is the sum of the squares of the differences between the data points and the model estimated points. This is facilitated by curve-fitting algorithms. Two curve-fitting methods, Levenberg-Marquardt and MINPACK-1, are investigated with respect to the search start points that they require and the accuracy of the returned fits. We have simulated one million dynamic contrast enhanced MRI curves using a range of parameters and investigated the use of single and multiple search starting points. We found that both algorithms, when used with a single starting point, return unreliable fits. When multiple start points are used, we found that both algorithms returned reliable parameters. However the MINPACK-1 method generally outperformed the Levenberg-Marquardt method. We conclude that the use of a single starting point when fitting compartmental modelling data such as this produces unsafe results and we recommend the use of multiple start points in order to find the global minima.

The relationship between vascular and metabolic characteristics of primary breast tumours

The objective of this study was to investigate the relationship between vascular and metabolic characteristics of breast tumours in vivo, using contrast-enhanced dynamic MRI and 2-[(18)F] fluoro-2-deoxy- d-glucose (FDG) PET imaging. Twenty patients with large or locally advanced primary breast cancers were imaged prior to therapy. MRI data were acquired using a dynamic gradient echo sequence and analysed using two pharmacokinetic models. Static PET data were acquired in 2D mode. A significant association ( P<0.05) was observed between the calculated exchange rate constants of both pharmacokinetic models and calculated PET FDG dose uptake ratios (DUR). Statistical analysis showed that the exchange rate constants can explain between 27 and 44% of the variance observed in the PET FDG uptake ratios. A relationship was demonstrated between the vascular and metabolic characteristics of primary breast tumours showing that any assessment of tumour metabolic activity using PET may be controlled at least in part by delivery of uptake agent due to the vascular characteristics of the tumour. MRI and PET provide methods of assessing breast tumour vascularity and metabolism in vivo using the exchange rate constants of dynamic MRI, and DUR of PET, respectively, these measures being related but not equivalent.