Phenotyping Superagers Using Resting-State fMRI

BACKGROUND AND PURPOSE

Superagers are defined as older adults with episodic memory performance similar or superior to that in middle-aged adults. This study aimed to investigate the key differences in discriminative networks and their main nodes between superagers and cognitively average elderly controls. In addition, we sought to explore differences in sensitivity in detecting these functional activities across the networks at 3T and 7T MR imaging fields.

MATERIALS AND METHODS

Fifty-five subjects 80 years of age or older were screened using a detailed neuropsychological protocol, and 31 participants, comprising 14 superagers and 17 cognitively average elderly controls, were included for analysis. Participants underwent resting-state-fMRI at 3T and 7T MR imaging. A prediction classification algorithm using a penalized regression model on the measurements of the network was used to calculate the probabilities of a healthy older adult being a superager. Additionally, ORs quantified the influence of each node across preselected networks.

RESULTS

The key networks that differentiated superagers and elderly controls were the default mode, salience, and language networks. The most discriminative nodes (ORs > 1) in superagers encompassed areas in the precuneus posterior cingulate cortex, prefrontal cortex, temporoparietal junction, temporal pole, extrastriate superior cortex, and insula. The prediction classification model for being a superager showed better performance using the 7T compared with 3T resting-state-fMRI data set.

CONCLUSIONS

Our findings suggest that the functional connectivity in the default mode, salience, and language networks can provide potential imaging biomarkers for predicting superagers. The 7T field holds promise for the most appropriate study setting to accurately detect the functional connectivity patterns in superagers.

The Brain Metabolic Signature in Superagers Using In Vivo 1H-MRS: A Pilot Study

BACKGROUND AND PURPOSE

Youthful memory performance in older adults may reflect an underlying resilience to the conventional pathways of aging. Subjects having this unusual characteristic have been recently termed "superagers." This study aimed to explore the significance of imaging biomarkers acquired by ¹H-MRS to characterize superagers and to differentiate them from their normal-aging peers.

MATERIALS AND METHODS

Fifty-five patients older than 80 years of age were screened using a detailed neuropsychological protocol, and 25 participants, comprising 12 superagers and 13 age-matched controls, were statistically analyzed. We used state-of-the-art 3T ¹H-MR spectroscopy to quantify 18 neurochemicals in the posterior cingulate cortex of our subjects. All ¹H-MR spectroscopy data were analyzed using LCModel. Results were further processed using 2 approaches to investigate the technique accuracy: 1) comparison of the average concentration of metabolites estimated with Cramer-Rao lower bounds <20%; and 2) calculation and comparison of the weighted means of metabolites' concentrations.

RESULTS

The main finding observed was a higher total N-acetyl aspartate concentration in superagers than in age-matched controls using both approaches (P = .02 and P = .03 for the weighted means), reflecting a positive association of total N-acetyl aspartate with higher cognitive performance.

CONCLUSIONS

¹H-MR spectroscopy emerges as a promising technique to unravel neurochemical mechanisms related to cognitive aging in vivo and providing a brain metabolic signature in superagers. This may contribute to monitoring future interventional therapies to avoid or postpone the pathologic processes of aging.

Applicability of the Test of Variables of Attention - T.O.V.A in Brazilian adults

The functioning of attention is complex, a primordial function in several cognitive processes and of great interest to neuropsychology. The Test of Variables of Attention (T.O.V.A) is a continuous computerized performance test that evaluates some attention components such as response time to a stimulus and errors due to inattention and impulsivity.

Higher arterial stiffness is associated with lower cognitive performance in patients with hypertension

Cognitive impairment and elevated arterial stiffness have been described in patients with arterial hypertension, but their association has not been well studied. We evaluated the correlation of arterial stiffness and different cognitive domains in patients with hypertension compared with those with normotension. We evaluated 211 patients (69 with normotension and 142 with hypertension). Patients were age matched and distributed according to their blood pressure: normotension, hypertension stage 1, and hypertension stage 2. Cognitive function was assessed using the Mini-Mental State Examination, Montreal Cognitive Assessment, and a battery of neuropsychological evaluations that assessed six main cognitive domains. Pulse wave velocity was measured using a Complior device, and carotid properties were assessed by radiofrequency ultrasound. Central arterial pressure and augmentation index were obtained using applanation tonometry. The hypertension stage 2 group had higher arterial stiffness and worse performance either by Mini-Mental State Examination (26.8±2.1 vs 27.3±2.1 vs 28.0±2.0, P=.003) or the Montreal Cognitive Assessment test (23.4±3.5 vs 24.9±2.9 vs 25.6±3.0, P<.001). On multivariable regression analysis, augmentation index, intima-media thickness, and pulse wave velocity were the variables mainly associated with lower cognitive performance at different cognitive domains. Cognitive impairment in different domains was associated with higher arterial stiffness.

Hypertension Severity Is Associated With Impaired Cognitive Performance

BACKGROUND

Most evidence of target-organ damage in hypertension (HTN) is related to the kidneys and heart. Cerebrovascular and cognitive impairment are less well studied. Therefore, this study analyzed changes in cognitive function in patients with different stages of hypertension compared to nonhypertensive controls.

METHODS AND RESULTS

In a cross-sectional study, 221 (71 normotensive and 150 hypertensive) patients were compared. Patients with hypertension were divided into 2 stages according to blood pressure (BP) levels or medication use (HTN-1: BP, 140-159/90-99 or use of 1 or 2 antihypertensive drugs; HTN-2: BP, ≥160/100 or use of ≥3 drugs). Three groups were comparatively analyzed: normotension, HTN stage 1, and HTN stage 2. The Mini-Mental State Examination, Montreal Cognitive Assessment, and a validated comprehensive battery of neuropsychological tests that assessed 6 main cognitive domains were used to determine cognitive function. Compared to the normotension and HTN stage-1, the severe HTN group had worse cognitive performance based on Mini-Mental State Examination (26.8±2.1 vs 27.4±2.1 vs 28.0±2.0; P=0.004) or Montreal Cognitive Assessment (23.4±3.7 vs 24.9±2.8 vs 25.5±3.2; P<0.001). On the neuropsychological tests, patients with hypertension had worse performance in language, processing speed, visuospatial abilities, and memory. Age, hypertension stage, and educational level were the best predictors of cognitive impairment in patients with hypertension in different cognitive domains.

CONCLUSIONS

Cognitive impairment was more frequent in patients with hypertension, and this was related to hypertension severity.