%0 Journal Article %J J Alzheimers Dis %D 2021 %T Longitudinal Trajectories in Cortical Thickness and Volume Atrophy: Superior Cognitive Performance Does Not Protect Against Brain Atrophy in Older Adults. %A Gardener, Samantha L %A Weinborn, Michael %A Sohrabi, Hamid R %A Doecke, James D %A Bourgeat, Pierrick %A Rainey-Smith, Stephanie R %A Shen, Kai-Kai %A Fripp, Jurgen %A Taddei, Kevin %A Maruff, Paul %A Salvado, Olivier %A Savage, Greg %A Ames, David %A Masters, Colin L %A Rowe, Christopher C %A Martins, Ralph N %X

BACKGROUND: Previous research has identified a small subgroup of older adults that maintain a high level of cognitive functioning well into advanced age. Investigation of those with superior cognitive performance (SCP) for their age is important, as age-related decline has previously been thought to be inevitable.

OBJECTIVE: Preservation of cortical thickness and volume was evaluated in 76 older adults with SCP and 100 typical older adults (TOAs) assessed up to five times over six years.

METHODS: Regions of interest (ROIs) found to have been associated with super-aging status (a construct similar to SCP status) in previous literature were investigated, followed by a discovery phase analyses of additional regions. SCPs were aged 70 + at baseline, scoring at/above normative memory (CVLT-II) levels for demographically similar individuals aged 30-44 years old, and in the unimpaired range for all other cognitive domains over the course of the study.

RESULTS: In linear mixed models, following adjustment for multiple comparisons, there were no significant differences between rates of thinning or volume atrophy between SCPs and TOAs in previously identified ROIs, or the discovery phase analyses. With only amyloid-β negative individuals in the analyses, again there were no significant differences between SCPs and TOAs.

CONCLUSION: The increased methodological rigor in classifying groups, together with the influence of cognitive reserve, are discussed as potential factors accounting for our findings as compared to the extant literature on those with superior cognitive performance for their age.

%B J Alzheimers Dis %V 81 %P 1039-1052 %8 2021 Jun 01 %G eng %N 3 %R 10.3233/JAD-201243 %0 Journal Article %J J Alzheimers Dis %D 2018 %T Alzheimer's Disease: A Journey from Amyloid Peptides and Oxidative Stress, to Biomarker Technologies and Disease Prevention Strategies-Gains from AIBL and DIAN Cohort Studies. %A Martins, Ralph N %A Villemagne, Victor %A Sohrabi, Hamid R %A Chatterjee, Pratishtha %A Shah, Tejal M %A Verdile, Giuseppe %A Fraser, Paul %A Taddei, Kevin %A Gupta, Veer B %A Rainey-Smith, Stephanie R %A Hone, Eugene %A Pedrini, Steve %A Lim, Wei Ling %A Martins, Ian %A Frost, Shaun %A Gupta, Sunil %A O'Bryant, Sid %A Rembach, Alan %A Ames, David %A Ellis, Kathryn %A Fuller, Stephanie J %A Brown, Belinda %A Gardener, Samantha L %A Fernando, Binosha %A Bharadwaj, Prashant %A Burnham, Samantha %A Laws, Simon M %A Barron, Anna M %A Goozee, Kathryn %A Wahjoepramono, Eka J %A Asih, Prita R %A Doecke, James D %A Salvado, Olivier %A Bush, Ashley I %A Rowe, Christopher C %A Gandy, Samuel E %A Masters, Colin L %X

Worldwide there are over 46 million people living with dementia, and this number is expected to double every 20 years reaching about 131 million by 2050. The cost to the community and government health systems, as well as the stress on families and carers is incalculable. Over three decades of research into this disease have been undertaken by several research groups in Australia, including work by our original research group in Western Australia which was involved in the discovery and sequencing of the amyloid-β peptide (also known as Aβ or A4 peptide) extracted from cerebral amyloid plaques. This review discusses the journey from the discovery of the Aβ peptide in Alzheimer's disease (AD) brain to the establishment of pre-clinical AD using PET amyloid tracers, a method now serving as the gold standard for developing peripheral diagnostic approaches in the blood and the eye. The latter developments for early diagnosis have been largely achieved through the establishment of the Australian Imaging Biomarker and Lifestyle research group that has followed 1,100 Australians for 11 years. AIBL has also been instrumental in providing insight into the role of the major genetic risk factor apolipoprotein E ɛ4, as well as better understanding the role of lifestyle factors particularly diet, physical activity and sleep to cognitive decline and the accumulation of cerebral Aβ.

%B J Alzheimers Dis %V 62 %P 965-992 %8 2018 %G eng %N 3 %1 http://www.ncbi.nlm.nih.gov/pubmed/29562546?dopt=Abstract %R 10.3233/JAD-171145 %0 Journal Article %J J Alzheimers Dis %D 2018 %T Associations of Dietary Protein and Fiber Intake with Brain and Blood Amyloid-β. %A Fernando, W M A D Binosha %A Rainey-Smith, Stephanie R %A Gardener, Samantha L %A Villemagne, Victor L %A Burnham, Samantha C %A Macaulay, S Lance %A Brown, Belinda M %A Gupta, Veer Bala %A Sohrabi, Hamid R %A Weinborn, Michael %A Taddei, Kevin %A Laws, Simon M %A Goozee, Kathryn %A Ames, David %A Fowler, Christopher %A Maruff, Paul %A Masters, Colin L %A Salvado, Olivier %A Rowe, Christopher C %A Martins, Ralph N %K Aged %K Alzheimer Disease %K Amyloid beta-Peptides %K Australia %K Biomarkers %K Brain %K Cognition %K Cohort Studies %K Cross-Sectional Studies %K Dietary Fiber %K Dietary Proteins %K Female %K Humans %K Logistic Models %K Male %K Middle Aged %K Neuropsychological Tests %K Positron-Emission Tomography %X

Accumulating evidence suggests a diet high in protein and fiber may confer some protection against Alzheimer's disease (AD). However, no human studies to-date have assessed the relationship between protein and fiber intake, and plasma and brain amyloid-β (Aβ). Consequently, this cross-sectional study, investigated the association of self-reported dietary intakes of protein and fiber, with plasma and brain Aβ burden (n = 541, and n = 162 respectively), in a well-characterized cohort of cognitively normal older adults, drawn from the larger Australian Imaging, Biomarkers and Lifestyle (AIBL) study of aging. We observed 12.59 and 8.43 higher odds of 'high' brain Aβ burden (PiB PET SUVR≥1.5) if protein intake fell in the lowest and middle tertile, respectively, compared to the highest tertile (p = 0.008; p = 0.013). Thus, in this cohort, the more protein consumed, the less likelihood of 'high' Aβ burden in the brain. No other significant associations were observed. The results of this study highlight the potentially protective impact of high dietary protein intake on brain Aβ burden in older adults, before objective memory decline is apparent. While longitudinal validation is required, these findings may assist in the development of dietary approaches aimed at preventing or delaying AD onset.

%B J Alzheimers Dis %V 61 %P 1589-1598 %8 2018 %G eng %N 4 %1 http://www.ncbi.nlm.nih.gov/pubmed/29376865?dopt=Abstract %R 10.3233/JAD-170742 %0 Journal Article %J J Alzheimers Dis %D 2017 %T Increased Carbohydrate Intake is Associated with Poorer Performance in Verbal Memory and Attention in an APOE Genotype-Dependent Manner. %A Gardener, Samantha L %A Rainey-Smith, Stephanie R %A Sohrabi, Hamid R %A Weinborn, Michael %A Verdile, Giuseppe %A Fernando, W M A D Binosha %A Lim, Yen Ying %A Harrington, Karra %A Burnham, Samantha %A Taddei, Kevin %A Masters, Colin L %A Macaulay, Stuart L %A Rowe, Christopher C %A Ames, David %A Maruff, Paul %A Martins, Ralph N %X

Evidence suggests that a diet low in carbohydrates can impact on cognitive performance among those with Alzheimer's disease (AD). However, there is a lack of data assessing this relationship among cognitively normal (CN) older adults at increased future risk of developing AD due to carriage of the apolipoprotein E (APOE) ɛ4 allele. We assessed the cross-sectional association between carbohydrate intake, cognitive performance, and cerebral amyloid-β (Aβ) load in CN older adults, genotyped for APOEɛ4 allele carrier status. Greater carbohydrate intake was associated with poorer performance in verbal memory in APOEɛ4 allele non-carriers, and poorer performance in attention in APOEɛ4 allele carriers. There were no associations between carbohydrate intake and cerebral Aβ load. These results provide support to the idea that decreasing carbohydrate intake may offer neurocognitive benefits, with specific cognitive domains affected in an APOE genotype-dependent manner. These findings warrant further investigation utilizing a longitudinal study design.

%B J Alzheimers Dis %V 58 %P 193-201 %G eng %N 1 %R 10.3233/JAD-161158 %0 Journal Article %J J Alzheimers Dis %D 2016 %T Cerebral Glucose Metabolism is Associated with Verbal but not Visual Memory Performance in Community-Dwelling Older Adults. %A Gardener, Samantha L %A Sohrabi, Hamid R %A Shen, Kai-Kai %A Rainey-Smith, Stephanie R %A Weinborn, Michael %A Bates, Kristyn A %A Shah, Tejal %A Foster, Jonathan K %A Lenzo, Nat %A Salvado, Olivier %A Laske, Christoph %A Laws, Simon M %A Taddei, Kevin %A Verdile, Giuseppe %A Martins, Ralph N %X

Increasing evidence suggests that Alzheimer's disease (AD) sufferers show region-specific reductions in cerebral glucose metabolism, as measured by [18F]-fluoro-2-deoxyglucose positron emission tomography (18F-FDG PET). We investigated preclinical disease stage by cross-sectionally examining the association between global cognition, verbal and visual memory, and 18F-FDG PET standardized uptake value ratio (SUVR) in 43 healthy control individuals, subsequently focusing on differences between subjective memory complainers and non-memory complainers. The 18F-FDG PET regions of interest investigated include the hippocampus, amygdala, posterior cingulate, superior parietal, entorhinal cortices, frontal cortex, temporal cortex, and inferior parietal region. In the cohort as a whole, verbal logical memory immediate recall was positively associated with 18F-FDG PET SUVR in both the left hippocampus and right amygdala. There were no associations observed between global cognition, delayed recall in logical memory, or visual reproduction and 18F-FDG PET SUVR. Following stratification of the cohort into subjective memory complainers and non-complainers, verbal logical memory immediate recall was positively associated with 18F-FDG PET SUVR in the right amygdala in those with subjective memory complaints. There were no significant associations observed in non-memory complainers between 18F-FDG PET SUVR in regions of interest and cognitive performance. We observed subjective memory complaint-specific associations between 18F-FDG PET SUVR and immediate verbal memory performance in our cohort, however found no associations between delayed recall of verbal memory performance or visual memory performance. It is here argued that the neural mechanisms underlying verbal and visual memory performance may in fact differ in their pathways, and the characteristic reduction of 18F-FDG PET SUVR observed in this and previous studies likely reflects the pathophysiological changes in specific brain regions that occur in preclinical AD.

%B J Alzheimers Dis %V 52 %P 661-72 %8 2016 Mar 31 %G eng %N 2 %1 http://www.ncbi.nlm.nih.gov/pubmed/27031482?dopt=Abstract %R 10.3233/JAD-151084 %0 Journal Article %J J Alzheimers Dis %D 2016 %T Diet and Inflammation in Alzheimer's Disease and Related Chronic Diseases: A Review. %A Gardener, Samantha L %A Rainey-Smith, Stephanie R %A Martins, Ralph N %K Alzheimer Disease %K Cardiovascular Diseases %K Chronic Disease %K Diet %K Humans %K Inflammation %K Neurodegenerative Diseases %X

Inflammation is one of the pathological features of the neurodegenerative disease, Alzheimer's disease (AD). A number of additional disorders are likewise associated with a state of chronic inflammation, including obesity, cardiovascular disease, and type-2 diabetes, which are themselves risk factors for AD. Dietary components have been shown to modify the inflammatory process at several steps of the inflammatory pathway. This review aims to evaluate the published literature on the effect of consumption of pro- or anti-inflammatory dietary constituents on the severity of both AD pathology and related chronic diseases, concentrating on the dietary constituents of flavonoids, spices, and fats. Diet-based anti-inflammatory components could lead to the development of potent novel anti-inflammatory compounds for a range of diseases. However, further work is required to fully characterize the therapeutic potential of such compounds, including gaining an understanding of dose-dependent relationships and limiting factors to effectiveness. Nutritional interventions utilizing anti-inflammatory foods may prove to be a valuable asset in not only delaying or preventing the development of age-related neurodegenerative diseases such as AD, but also treating pre-existing conditions including type-2 diabetes, cardiovascular disease, and obesity.

%B J Alzheimers Dis %V 50 %P 301-34 %8 2016 %G eng %N 2 %1 http://www.ncbi.nlm.nih.gov/pubmed/26682690?dopt=Abstract %R 10.3233/JAD-150765