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Sökning: WFRF:(Kalpouzos Grégoria)

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1.
  • Hooshmand, Babak, et al. (författare)
  • Association of Methionine to Homocysteine Status With Brain Magnetic Resonance Imaging Measures and Risk of Dementia
  • 2019
  • Ingår i: JAMA psychiatry. - : American Medical Association. - 2168-6238 .- 2168-622X. ; 76:11, s. 1198-1205
  • Tidskriftsartikel (refereegranskat)abstract
    • IMPORTANCE Impairment of methylation status (ie, methionine to homocysteine ratio) may be a modifiable risk factor for structural brain changes and incident dementia.OBJECTIVE To investigate the association of serum markers of methylation status and sulfur amino acids with risk of incident dementia, Alzheimer disease (AD), and the rate of total brain tissue volume loss during 6 years.DESIGN, SETTING, AND PARTICIPANTS This population-based longitudinal study was performed from March 21, 2001, to October 10, 2010, in a sample of 2570 individuals aged 60 to 102 years from the Swedish Study on Aging and Care in Kungsholmen who were dementia free at baseline and underwent comprehensive examinations and structural brain magnetic resonance imaging (MRI) on 2 to 3 occasions during 6 years. Data analysis was performed from March 1, 2018, to October 1, 2018.MAIN OUTCOMES AND MEASURES Incident dementia, AD, and the rate of total brain volume loss.RESULTS This study included 2570 individuals (mean [SD] age, 73.1 [10.4] years; 1331 [56.5%] female). The methionine to homocysteine ratio was higher in individuals who consumed vitamin supplements (median, 1.9; interquartile range [IQR], 1.5-2.6) compared with those who did not (median, 1.8; IQR, 1.3-2.3; P<.001) and increased per each quartile increase of vitamin B-12 or folate. In the multiadjusted model, an elevated baseline serum total homocysteine level was associated with an increased risk of dementia and AD during 6 years: for the highest homocysteine quartile compared with the lowest, the hazard ratios (HRs) were 1.60 (95% CI, 1.01-2.55) for dementia and 2.33 (95% CI, 1.26-4.30) for AD. In contrast, elevated concentrations of methionine were associated with a decreased risk of dementia (HR, 0.54; 95% CI, 0.36-0.81) for the highest quartile compared with the lowest. Higher values of the methionine to homocysteine ratio were significantly associated with lower risk of dementia and AD: for the fourth methionine-homocysteine quartile compared with the first quartile, the HR was 0.44 (95% CI, 0.27-0.71) for incident dementia and 0.43 (95% CI, 0.23-0.80) for AD. In the multiadjusted linear mixed models, a higher methionine to homocysteine ratio was associated with a decreased rate of total brain tissue volume loss during the study period (beta [SE] per 1-SD increase, 0.038 [0.014]; P=.007).CONCLUSIONS AND RELEVANCE The methionine to homocysteine status was associated with dementia development and structural brain changes during the 6-year study period, suggesting that a higher methionine to homocysteine ratio may be important in reducing the rate of brain atrophy and decreasing the risk of dementia in older adults.
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2.
  • Kalpouzos, Grégoria, et al. (författare)
  • Higher Striatal Iron Concentration is Linked to Frontostriatal Underactivation and Poorer Memory in Normal Aging
  • 2017
  • Ingår i: Cerebral Cortex. - : Oxford University Press. - 1047-3211 .- 1460-2199. ; 27:6, s. 3427-3436
  • Tidskriftsartikel (refereegranskat)abstract
    • In the brain, intracellular iron is essential for cellular metabolism. However, an overload of free iron is toxic, inducing oxidative stress and cell death. Although an increase of striatal iron has been related to atrophy and impaired cognitive performance, the link between elevated iron and altered brain activity in aging remains unexplored. In a sample of 37 younger and older adults, we examined whether higher striatal iron concentration could underlie age-related differences in frontostriatal activity induced by mental imagery of motor and non-motor scenes, and poorer recall of the scenes. Higher striatal iron concentration was linked to underrecruitment of frontostriatal regions regardless of age and striatal volume, the iron-activity association in right putamen being primarily driven by the older adults. In older age, higher striatal iron was related to poorer memory. Altered astrocytic functions could account for the link between brain iron and brain activity, as astrocytes are involved in iron buffering, neurovascular coupling, and synaptic activity. Our preliminary findings, which need to be replicated in a larger sample, suggest a potential frontostriatal target for intervention to counteract negative effects of iron accumulation on brain function and cognition.
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3.
  • Kalpouzos, Gregoria, et al. (författare)
  • Local brain atrophy accounts for functional activity differences in normal aging
  • 2012
  • Ingår i: Neurobiology of Aging. - : Elsevier. - 0197-4580 .- 1558-1497. ; 33:3, s. 623.e1-
  • Tidskriftsartikel (refereegranskat)abstract
    • Functional brain imaging studies of normal aging typically show age-related under-and overactivations during episodic memory tasks. Older individuals also undergo nonuniform gray matter volume (GMv) loss. Thus, age differences in functional brain activity could at least in part result from local atrophy. We conducted a series of voxel-based blood oxygen level-dependent (BOLD)-GMv analyses to highlight whether age-related under-and overrecruitment was accounted for by GMv changes. Occipital GMv loss accounted for underrecruitment at encoding. Efficiency reduction of sensory-perceptual mechanisms underpinned by these areas may partly be due to local atrophy. At retrieval, local GMv loss accounted for age-related overactivation of left dorsolateral prefrontal cortex, but not of left dorsomedial prefrontal cortex. Local atrophy also accounted for age-related overactivation in left lateral parietal cortex. Activity in these frontoparietal regions correlated with performance in the older group. Atrophy in the overrecruited regions was modest in comparison with other regions as shown by a between-group voxel-based morphometry comparison. Collectively, these findings link age-related structural differences to age-related functional under-as well as overrecruitment.
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4.
  • Prinelli, Federica, et al. (författare)
  • Specific nutrient patterns are associated with higher structural brain integrity in dementia-free older adults
  • 2019
  • Ingår i: NeuroImage. - : Elsevier. - 1053-8119 .- 1095-9572. ; 199, s. 281-288
  • Tidskriftsartikel (refereegranskat)abstract
    • Optimal nutrition may play a beneficial role in maintaining a healthy brain. However, the relationship between nutrient intake and brain integrity is largely unknown. We investigated the association of specific nutrient dietary patterns with structural characteristics of the brain. Within the population-based Swedish National study on Aging and Care-Kungsholmen (SNAC-K), a cross-sectional study of 417 dementia-free participants aged >= 60 years who underwent structural magnetic resonance imaging (MRI) scans during 2001-2003, was carried-out. Data on dietary intake were collected using a food frequency questionnaire, from which intake of 21 nutrients was estimated. By principal component analysis, five nutrient patterns were extracted: (1) NP1 was characterized by fiber, vitamin C, E, beta-carotene, and folate [Fiber&Antioxidants], (2) NP2 by eicosapentaenoic (EPA, 20:5 omega-3) and docosahexaenoic (DHA, 22:6 omega-3) polyunsaturated fatty acids (PUFAs), proteins, cholesterol, vitamin B3, B12, and D [long chain (LC) omega-3PUFAs&Proteins], (3) NP3 by alpha-linoleic (18:2 omega-6) and alpha-linolenic (18:3 omega-3) PUFAs, monounsaturated fatty acids (MUFAs), and vitamin E [MUFAs &omega-3,6PUFAs], (4) NP4 by saturated fatty acids (SFAs), trans fats, MUFAs, and cholesterol [SFAs&Trans fats], (5) NP5 by B-vitamins, retinol, and proteins [B-Vitamins&Retinol]. Nutrient patterns scores were tertiled with the lowest tertile as reference, and were related to total brain volume (TBV) and white matter hyperintensities volume (WMHV) using linear regression models adjusting for potential confounders. In the multi-adjusted model, compared to the lowest intake for each pattern, the highest intake of NP1 (beta = 11.11, P = 0.009), NP2 (beta = 7.47, P = 0.052), and NP3 (beta = 10.54, P = 0.005) was associated with larger TBV whereas NP5 was related to smaller TBV (beta = -12.82, P = 0.001). The highest intake of NP1 was associated with lower WMHV (beta = -0.32, P = 0.049), whereas NP4 was associated with greater WMHV (beta = 0.31, P = 0.036). In sum, our results suggest that the identified brain-health specific nutrient combinations characterized by higher intake of fruit, vegetables, legumes, olive and seed oils, fish, lean red meat, poultry and low in milk and dairy products, cream, butter, processed meat and offal, were strongly associated with greater brain integrity among older adults.
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5.
  • Salami, Alireza, et al. (författare)
  • Functional coherence of striatal resting-state networks is modulated by striatal iron content
  • 2018
  • Ingår i: NeuroImage. - : Academic Press. - 1053-8119 .- 1095-9572. ; 183, s. 495-503
  • Tidskriftsartikel (refereegranskat)abstract
    • Resting-state spontaneous fluctuations have revealed individual differences in the functional architecture of brain networks. Previous research indicates that the striatal network shows alterations in neurological conditions but also in normal aging. However, the neurobiological mechanisms underlying individual differences in striatal resting-state networks (RSNs) have been less explored. One candidate that may account for individual differences in striatal spontaneous activity is the level of local iron accumulation. Excessive iron in the striatum has been linked to a loss of structural integrity and reduced brain activity during task performance in aging. Using independent component analysis in a sample of 42 younger and older adults, we examined whether higher striatal iron content, quantified using relaxometry, underlies individual differences in spontaneous fluctuations of RSNs in general, and of the striatum in particular. Higher striatal iron content was linked to lower spontaneous coherence within both caudate and putamen RSNs regardless of age. No such links were observed for other RSNs. Moreover, the number of connections between the putamen and other RSNs was negatively associated with iron content, suggesting that iron modulated the degree of cross-talk between the striatum and cerebral cortex. Importantly, these associations were primarily driven by the older group. Finally, a positive association was found between coherence in the putamen and motor performance, suggesting that this spontaneous activity is behaviorally meaningful. A follow-up mediation analysis also indicated that functional connectivity may mediate the link between striatal iron and motor performance. Our preliminary findings suggest that striatal iron potentially accounts for individual differences in spontaneous striatal fluctuations, and might be used as a locus of intervention.
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6.
  • Wang, Rui, et al. (författare)
  • MRI load of cerebral microvascular lesions and neurodegeneration, cognitive decline, and dementia
  • 2018
  • Ingår i: Neurology. - 0028-3878 .- 1526-632X. ; 91:16, s. 1487-1497
  • Tidskriftsartikel (refereegranskat)abstract
    • Objective To explore the differential associations of neurodegeneration and microvascular lesion load with cognitive decline and dementia in older people and the modifying effect of the APOE genotype on these associations. Methods A sample of 436 participants (age >= 60 years) was derived from the population-based Swedish National study on Aging and Care in Kungsholmen, Stockholm, and clinically examined at baseline (2001-2003) and 3 occasions during the 9-year follow-up. At baseline, we assessed microvascular lesion load using a summary score for MRI markers of lacunes, white matter hyperintensities (WMHs), and perivascular spaces and neurodegeneration load for markers of enlarged ventricles, smaller hippocampus, and smaller gray matter. We assessed cognitive function using the Mini-Mental State Examination (MMSE) test and diagnosed dementia following the Diagnostic and Statistical Manual of Mental Disorders, 4th edition criteria. We analyzed data using linear mixed-effects, mediation, and random-effects Cox models. Results During the follow-up, 46 participants were diagnosed with dementia. Per 1-point increase in microvascular lesion and neurodegeneration score (range 0-3) was associated with multiple adjusted beta-coefficients of -0.35 (95% confidence interval, -0.51 to -0.20) and -0.44 (-0.56 to -0.32), respectively, for the MMSE score and multiple adjusted hazard ratios of 1.68 (1.12-2.51) and 2.35 (1.58-3.52), respectively, for dementia; carrying APOE epsilon 4 reinforced the associations with MMSE decline. WMH volume changes during the follow-up mediated 66.9% and 12.7% of the total association of MMSE decline with the baseline microvascular score and neurodegeneration score, respectively. Conclusions Both cerebral microvascular lesion and neurodegeneration loads are strongly associated with cognitive decline and dementia. The cognitive decline due to microvascular lesions is exacerbated by APOE epsilon 4 and is largely attributed to progression and development of microvascular lesions.
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7.
  • Persson, Jonas, et al. (författare)
  • Preserved Hippocampus Activation in Normal Aging as Revealed by fMRI
  • 2011
  • Ingår i: Hippocampus. - : Wiley-Liss, Inc.. - 1050-9631 .- 1098-1063. ; 21:7, s. 753-766
  • Tidskriftsartikel (refereegranskat)abstract
    • The hippocampus is deteriorated in various pathologies such as Alzheimer's disease (AD) and such deterioration has been linked to memory impairment. By contrast, the structural and functional effects of normal aging on the hippocampus is a matter of debate, with some findings suggesting deterioration and others providing evidence of preservation. This constitutes a crucial question since many investigations on AD are based on the assumption that the deterioration of the hippocampus is the breaking point between normal and pathological aging. A growing number of fMRI studies specifically aimed at investigating hippocampal engagement in various cognitive tasks, notably memory tasks, but the results have been inconclusive. Here, we optimized the episodic face-name paired-associates task in order to test the functioning of the hippocampus in normal aging. Critically, we found no difference in the activation of the hippocampus between the young and a group of older participants. Analysis of individual patterns of activation substantiated this impression. Collectively, these findings provide evidence of preserved hippocampal functioning in normal aging.
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8.
  • Becker, Nina, et al. (författare)
  • Differential Effects of Encoding Instructions on Brain Activity Patterns of Item and Associative Memory
  • 2017
  • Ingår i: Journal of cognitive neuroscience. - : MIT Press. - 0898-929X .- 1530-8898. ; 29:3, s. 545-559
  • Tidskriftsartikel (refereegranskat)abstract
    • Evidence from neuroimaging studies suggests a critical role of hippocampus and inferior frontal gyrus (IFG) in associative relative to item encoding. Here, we investigated similarities and differences in functional brain correlates for associative and item memory as a function of encoding instruction. Participants received either incidental (animacy judgments) or intentional encoding instructions while fMRI was employed during the encoding of associations and items. In a subsequent recognition task, memory performance of participants receiving intentional encoding instructions was higher compared with those receiving incidental encoding instructions. Furthermore, participants remembered more items than associations, regardless of encoding instruction. Greater brain activation in the left anterior hippocampus was observed for intentionally compared with incidentally encoded associations, although activity in this region was not modulated by the type of instruction for encoded items. Furthermore, greater activity in the left anterior hippocampus and left IFG was observed during intentional associative compared with item encoding. The same regions were related to subsequent memory of intentionally encoded associations and were thus task relevant. Similarly, connectivity of the anterior hippocampus to the right superior temporal lobe and IFG was uniquely linked to subsequent memory of intentionally encoded associations. Our study demonstrates the differential involvement of anterior hippocampus in intentional relative to incidental associative encoding. This finding likely reflects that the intent to remember triggers a specific binding process accomplished by this region.
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9.
  • Becker, Nina, et al. (författare)
  • Structural brain correlates of associative memory in older adults
  • 2015
  • Ingår i: NeuroImage. - 1053-8119 .- 1095-9572. ; 118, s. 146-153
  • Tidskriftsartikel (refereegranskat)abstract
    • Associative memory involves binding two or more items into a coherent memory episode. Relative to memory for single items, associative memory declines greatly in aging. However, older individuals vary substantially in their ability to memorize associative information. Although functional studies link associative memory to the medial temporal lobe (MTL) and prefrontal cortex (PFC), little is known about how volumetric differences in MTL and PFC might contribute to individual differences in associative memory. We investigated regional gray-matter volumes related to individual differences in associative memory in a sample of healthy older adults (n = 54; age = 60 years). To differentiate item from associative memory, participants intentionally learned face-scene picture pairs before performing a recognition task that included single faces, scenes, and face-scene pairs. Gray-matter volumes were analyzed using voxel-based morphometry region-of-interest (ROI) analyses. To examine volumetric differences specifically for associative memory, item memory was controlled for in the analyses. Behavioral results revealed large variability in associative memory that mainly originated from differences in false-alarm rates. Moreover, associative memory was independent of individuals' ability to remember single items. Older adults with better associative memory showed larger gray-matter volumes primarily in regions of the left and right lateral PFC. These findings provide evidence for the importance of PFC in intentional learning of associations, likely because of its involvement in organizational and strategic processes that distinguish older adults with good from those with poor associative memory.
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10.
  • Becker, Nina, et al. (författare)
  • Structure-function associations of successful associative encoding
  • 2019
  • Ingår i: NeuroImage. - : Elsevier. - 1053-8119 .- 1095-9572. ; 201
  • Tidskriftsartikel (refereegranskat)abstract
    • Functional magnetic resonance imaging (MRI) studies have demonstrated a critical role of hippocampus and inferior frontal gyrus (IFG) in associative memory. Similarly, evidence from structural MRI studies suggests a relationship between gray-matter volume in these regions and associative memory. However, how brain volume and activity relate to each other during associative-memory formation remains unclear. Here, we used joint independent component analysis (jICA) to examine how gray-matter volume and brain activity would be associated during associative encoding, especially in medial-temporal lobe (MTL) and IFG. T1-weighted images were collected from 27 young adults, and functional MRI was employed during intentional encoding of object pairs. A subsequent recognition task tested participants' memory performance. Unimodal analyses using voxel-based morphometry revealed that participants with better associative memory showed larger gray-matter volume in left anterior hippocampus. Results from the jICA revealed one component that comprised a covariance pattern between gray-matter volume in anterior and posterior MTL and encoding-related activity in IFG. Our findings suggest that gray matter within the MTL modulates distally distinct parts of the associative encoding circuit, and extend previous studies that demonstrated MTL-IFG functional connectivity during associative memory tasks.
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