Cortical thickness and resting-state cardiac function across the lifespan: A cross-sectional pooled mega-analysis

Understanding the association between autonomic nervous system [ANS] function and brain morphology across the lifespan provides important insights into neurovisceral mechanisms underlying health and disease. Resting-state ANS activity, indexed by measures of heart rate [HR] and its variability [HRV] has been associated with brain morphology, particularly cortical thickness [CT]. While findings have been mixed regarding the anatomical distribution and direction of the associations, these inconsistencies may be due to sex and age differences in HR/HRV and CT. Previous studies have been limited by small sample sizes, which impede the assessment of sex differences and aging effects on the association between ANS function and CT. To overcome these limitations, 20 groups worldwide contributed data collected under similar protocols of CT assessment and HR/HRV recording to be pooled in a mega-analysis (N = 1,218 (50.5% female), mean age 36.7 years (range: 12-87)). Findings suggest a decline in HRV as well as CT with increasing age. CT, particularly in the orbitofrontal cortex, explained additional variance in HRV, beyond the effects of aging. This pattern of results may suggest that the decline in HRV with increasing age is related to a decline in orbitofrontal CT. These effects were independent of sex and specific to HRV; with no significant association between CT and HR. Greater CT across the adult lifespan may be vital for the maintenance of healthy cardiac regulation via the ANS-or greater cardiac vagal activity as indirectly reflected in HRV may slow brain atrophy. Findings reveal an important association between CT and cardiac parasympathetic activity with implications for healthy aging and longevity that should be studied further in longitudinal research.

Emotional arousal amplifies competitions across goal-relevant representation: A neurocomputational framework

Emotional arousal often facilitates memory for some aspects of an event while impairing memory for other aspects of the same event. Across three experiments, we found that emotional arousal amplifies competition among goal-relevant representations, such that arousal impairs memory for multiple goal-relevant representations while enhancing memory for solo goal-relevant information. We also present a computational model to explain the mechanisms by which emotional arousal can modulate memory in opposite ways via the local/synaptic-level noradrenergic system. The model is based on neurophysiological observations that norepinephrine (NE) released under emotional arousal is locally controlled by glutamate levels, resulting in different NE effects across regions, gating either long-term potentiation or long-term depression by activating different adrenergic receptors depending on NE concentration levels. This model successfully replicated behavioral findings from the three experiments. These findings suggest that the NE's local effects are key in determining the effects of emotion on memory.

Arousal increases neural gain via the locus coeruleus-norepinephrine system in younger adults but not in older adults

In younger adults, arousal amplifies attentional focus to the most salient or goal-relevant information while suppressing other information. A computational model of how the locus coeruleus-norepinephrine (LC-NE) system can implement this increased selectivity under arousal and an fMRI study comparing how arousal affects younger and older adults' processing indicate that the amplification of salient stimuli and the suppression of non-salient stimuli are separate processes, with aging affecting suppression without impacting amplification under arousal. In the fMRI study, arousal increased processing of salient stimuli and decreased processing of non-salient stimuli for younger adults. In contrast, for older adults, arousal increased processing of both low and high salience stimuli, generally increasing excitatory responses to visual stimuli. Older adults also showed decline in LC functional connectivity with frontoparietal networks that coordinate attentional selectivity. Thus, among older adults, arousal increases the potential for distraction from non-salient stimuli.

Brain structural concomitants of resting state heart rate variability in the young and old: evidence from two independent samples

Previous research has shown associations between brain structure and resting state high-frequency heart rate variability (HF HRV). Age affects both brain structure and HF HRV. Therefore, we sought to examine the relationship between brain structure and HF HRV as a function of age. Data from two independent studies were used for the present analysis. Study 1 included 19 older adults (10 males, age range 62-78 years) and 19 younger adults (12 males, age range 19-37). Study 2 included 23 older adults (12 males; age range 55-75) and 27 younger adults (17 males; age range 18-34). The root-mean-square of successive R-R-interval differences (RMSSD) from ECG recordings was used as time-domain measure of HF HRV. MRI scans were performed on a 3.0-T Siemens Magnetom Trio scanner. Cortical reconstruction and volumetric segmentation were performed with the Freesurfer image analysis suite, including 12 regions as regions of interests (ROI). Zero-order and partial correlations were used to assess the correlation of RMSSD with cortical thickness in selected ROIs. Lateral orbitofrontal cortex (OFC) cortical thickness was significantly associated with RMSSD. Further, both studies, in line with previous research, showed correlations between RMSSD and anterior cingulate cortex (ACC) cortical thickness. Meta-analysis on adjusted correlation coefficients from individual studies confirmed an association of RMSSD with the left rostral ACC and the left lateral OFC. Future longitudinal studies are necessary to trace individual trajectories in the association of HRV and brain structure across aging.

Higher locus coeruleus MRI contrast is associated with lower parasympathetic influence over heart rate variability

The locus coeruleus (LC) is a key node of the sympathetic nervous system and suppresses parasympathetic activity that would otherwise increase heart rate variability. In the current study, we examined whether LC-MRI contrast reflecting neuromelanin accumulation in the LC was associated with high-frequency heart rate variability (HF-HRV), a measure reflecting parasympathetic influences on the heart. Recent evidence indicates that neuromelanin, a byproduct of catecholamine metabolism, accumulates in the LC through young and mid adulthood, suggesting that LC-MRI contrast may be a useful biomarker of individual differences in habitual LC activation. We found that, across younger and older adults, greater LC-MRI contrast was negatively associated with HF-HRV during fear conditioning and spatial detection tasks. This correlation was not accounted for by individual differences in age or anxiety. These findings indicate that individual differences in LC structure relate to key cardiovascular parameters.

Neuromelanin marks the spot: identifying a locus coeruleus biomarker of cognitive reserve in healthy aging

Leading a mentally stimulating life may build up a reserve of neural and mental resources that preserve cognitive abilities in late life. Recent autopsy evidence links neuronal density in the locus coeruleus (LC), the brain's main source of norepinephrine, to slower cognitive decline before death, inspiring the idea that the noradrenergic system is a key component of reserve (Robertson, I. H. 2013. A noradrenergic theory of cognitive reserve: implications for Alzheimer's disease. Neurobiol. Aging. 34, 298-308). Here, we tested this hypothesis using neuromelanin-sensitive magnetic resonance imaging to visualize and measure LC signal intensity in healthy younger and older adults. Established proxies of reserve, including education, occupational attainment, and verbal intelligence, were linearly correlated with LC signal intensity in both age groups. Results indicated that LC signal intensity was significantly higher in older than younger adults and significantly lower in women than in men. Consistent with the LC-reserve hypothesis, both verbal intelligence and a composite reserve score were positively associated with LC signal intensity in older adults. LC signal intensity was also more strongly associated with attentional shifting ability in older adults with lower cognitive reserve. Together these findings link in vivo estimates of LC neuromelanin signal intensity to cognitive reserve in normal aging.

Dedifferentiation of emotion regulation strategies in the aging brain

Different emotion regulation strategies are distinctly represented in the brains of younger adults. Decreasing a reaction to a negative situation by reinterpreting it (reappraisal) relies on cognitive control regions in the prefrontal cortex, while distracting away from a stressor involves more posterior medial structures. In this study, we used Multi-Voxel pattern analyses (MVPA) to examine whether reappraisal and distraction strategies have distinct representations in the older adult brain, or whether emotion regulation strategies become more dedifferentiated in later life. MVPA better differentiated the two emotion regulation strategies for younger adults than for older adults, and revealed the greatest age-related differences in differentiation in the posterior medial cortex (PMC). Univariate analyses revealed equal PMC recruitment across strategies for older adults, but greater activity during distraction than reappraisal for younger adults. The PMC is central to self-focused processing, and thus our findings are consistent with the possibility that focusing on the self may be a default mechanism across emotion regulation strategies for older people.

Hearing something emotional influences memory for what was just seen: How arousal amplifies effects of competition in memory consolidation

Enhanced memory for emotional items often comes at the cost of memory for the background scenes. Because emotional foreground items both induce arousal and attract attention, it is not clear whether the emotion effects are simply the result of shifts in visual attention during encoding or whether arousal has effects beyond simple attention capture. In the current study, participants viewed a series of scenes that each either had a foreground object or did not have one, and then, after each image, heard either an emotionally arousing negative sound or a neutral sound. After a 24-hr delay, they returned for a memory test for the objects and scenes. Postencoding arousal decreased recognition memory of scenes shown behind superimposed objects but not memory of scenes shown alone. These findings support the hypothesis that arousal amplifies the effects of competition between mental representations, influencing memory consolidation of currently active representations.

Single-agent gemcitabine is active in previously treated metastatic breast cancer

BACKGROUND

This phase II study was designed to assess the efficacy and safety of gemcitabine in patients with metastatic breast cancer (MBC) previously treated with an anthracycline- or anthracenedione-containing regimen as first-line therapy for metastatic disease.

PATIENTS AND METHODS

Forty-seven patients with MBC were enrolled in five French centers. Patients were eligible if they had received one prior chemotherapy regimen with an anthracycline or anthracenedione for metastatic disease, if they had responded to that prior regimen, and if they had relapsed at least 6 months after the first response. Fifteen patients received more than one prior anthracycline regimen; thus, gemcitabine was third-line therapy for 30% of patients. Gemcitabine 1,200 mg/m(2) was administered as a 30-min intravenous infusion on days 1, 8, and 15 of a 28-day cycle for a maximum of eight cycles after the best response was obtained.

RESULTS

Objective responses were seen in 12 of 41 assessable patients (4 complete responses and 8 partial responses), for an objective response rate of 29% (95% confidence interval, 16-46%). The median response duration was 8.1 months (range: 2.5-27.4 months). Serious hematological toxicity was minimal, with grade 4 neutropenia in 2% of the patients (no neutropenic fever), grade 3 neutropenia in 28% of the patients, and grade 3 thrombocytopenia in 6% of the patients. Among the nonhematological toxicities, asthenia was the most common.

CONCLUSIONS

Gemcitabine given at this dose and schedule is a well-tolerated treatment with definitive antitumor activity in pretreated MBC patients. This result warrants future exploration of the use of gemcitabine as a single agent and in combination in patients with MBC.

[A phase II multicenter study of gemcitabine in non small cell lung cancers]

Gemcitabine is a novel pyrimidine nucleoside whose activity has been demonstrated on solid tumors. We report here the results of a multicentre phase II trial of gemcitabine in chemonaive patients with inoperable non small cell lung cancer (NSCLC). Gemcitabine was given weekly at a dose of 1,250 mg/m2 administered as a 30 min intravenous infusion, for 3 weeks followed by 1 week of rest (1 cycle). All the 161 patients included were evaluable for toxicity and 151 of them were evaluable for efficacy. The majority of patients had a stage IIIb (31.1%) or stage IV (64.6%) disease; 10.6%, 83.2% and 6.2% of patients had a WHO performance status (PS) 0, 1, and 2, respectively. Adenocarcinoma accounted for 52.2% of cases and squamous cell carcinoma for 43.5% of cases. Three complete responses and 30 partial responses gave an objective response (OR) rate of 21.8% (95% confidence interval; 15.5-29.3%). All responses were validated by an independent Oncology Review Board. Median duration of response was 7.6 months. Median time to progression was 4.6 months (3.3 months in non responders and 7.6 months in responders). Median survival was 7.3 months in non responders and 13.4 months in responders (p < 0.001), which gave an overall median survival of 8.9 months (95% CI: 0.1-21.9 months) in the entire study population. An improvement of symptoms and personal state was also observed. Treatment was well tolerated. Neutropenia was the only dose limiting toxicity. WHO grade 3 or 4 neutropenia occurred in 19.6% and 5.7% of patients, respectively. With a 21.8% OR rate, this multicentre study confirms the activity of gemcitabine as a single agent in patients with inoperable NSCLC. Its good tolerance and original mode of action make gemcitabine a drug of choice in the therapeutic strategy of these tumors.

Myeloma cell growth arrest, apoptosis, and interleukin-6 receptor modulation induced by EB1089, a vitamin D3 derivative, alone or in association with dexamethasone

We have previously shown that malignant plasma cells expressed the specific receptor for 1,25-dihydroxyvitamin D3 and that this derivative could significantly inhibit the proliferation of such malignant cells. More recently, new vitamin D3 derivatives have been generated with extraordinarily potent inhibitory effects on leukemic cell growth in vitro. These new data prompted us to (re)investigate the capacity of such new vitamin D3 derivatives to inhibit myeloma cell growth in comparison with that of dexamethasone, a potent antitumoral agent in multiple myeloma. In the current study, we show that EB1089, a new vitamin D3 derivative, (1) induces G1 growth arrest of human myeloma cells, which is only partially reversed by interleukin-6 (IL-6); (2) induces apoptosis in synergy with dexamethasone, IL-6, leukemia-inhibitory factor, and Oncostatin M, with an agonistic anti-gp130 monoclonal antibody being unable to prevent this apoptosis; (3) downregulates both the gp80 (ie, the alpha chain of the IL-6 receptor [IL-6Ralpha]) expression on malignant plasma cells and the production of soluble IL-6Ralpha, and finally (4) inhibits the deleterious upregulation of gp80 expression induced by dexamethasone while limiting the dexamethasone-induced upregulation of gp130 expression. Considering that these in vitro effects of EB1089 have been observed at doses obtainable in vivo (without hypercalcemic effects), our present data strongly suggest that EB1089 could have a true interest in the treatment of multiple myeloma, especially in association with dexamethasone.

[Serum osteocalcin and diabetes mellitus. A study of 98 patients]

The goal of this study was to evaluate in 98 diabetic patients the serum levels of osteocalcin (OC) and their relationship with glycosylated hemoglobin levels and with the duration, calculated in years, of the disease. Patients were divided in 3 groups: 17 IDDM patients, 62 NIDDM patients treated with oral hypoglycaemic agents, and 19 NIDDM patients treated with insulin. Results were compared to 2 different control groups. In IDDM patients OC serum levels were significantly lower if compared either to control group and to NIDDM patients. The 2 groups of NIDDM patients showed significantly higher OC values than controls. No significant relationship resulted between OC levels, the duration of diabetes and the glycosylated hemoglobin values. The results of the study indicate a direct correlation between pancreatic function and osteoblastic activity: insulin lack is associated with reduced OC serum levels.