[Cognitive functions and modifiable risk factors for chronic non-communicable diseases in ageing in a Russian population sample.]

We aimed to investigate the relationship between the indicators of cognitive functions (CF) and modifiable risk factors for chronic non-communicable diseases (NCD) in a cross-sectional analysis in the urban Russian population sample aged 55-84 years. The study investigated a random sample of 3 153 people (men and women 55-84 years old) from a general population cohort of Novosibirsk residents; a sample was examined within the international project HAPIEE. The study protocol included standardized neuropsychological tests (quantitative assessment of memory, semantic verbal fluency, attention and processing speed) and standardized assessment of risk factors, history and treatment of cardiovascular disease and NCD. In cross-sectional analysis we observed a positive relationship of CF indices with level of education and an inverse relationship with metabolic risk factors and smoking in both sexes. The level of total cholesterol and moderate alcohol consumption had positive relationship with CF indices in women. These associations were independent from age and other factors.

Cardiovascular disease risk factors and cognitive functions in older Russian adults

Background

The prevalence of cardiovascular diseases (CVD) is increasing due to the global trend towards an aging population. CVD and cerebrovascular disease have a negative impact on cognitive health, and CVD risk factors may also be associated with cognitive decline with aging.

Purpose

To investigate associations of modifiable risk factors for CVD with cognitive functions (CF) in older Russian adults.

Methods

A random population sample (3153 men and women, aged 55–84 years) was examined in our city in the 3rd wave of the Russian arm of the international project HAPIEE (Health, Alcohol, and Psychosocial Factors in Eastern Europe). We used standardized epidemiological and instrumental methods for assessment of risk factors, history and treatment of CVD. Cognitive tests included the assessment of memory indicators (immediate and delayed recall), semantic verbal fluency (animal naming), attention, concentration and processing speed (letter cancellation task). Associations between CVD risk factors and cognitive indices were analyzed cross-sectionally.

Results

Mean age in men was of 69.2±7.0 years (n=1198), in women - 69.7±6.9 (n=1955). In both sexes all cognitive domains were positively associated with education and negatively with age (p<0.001 for all cases). In men, after adjusting for health and lifestyle conditions, systolic blood pressure had inverse association with semantic verbal fluency (p=0.015); level of plasma glucose (p=0.003), waist-to-hip ratio (p=0.013) and smoking (p=0.028) were negative associated with letter cancellation task. In multivariate analyses in women, frequency of alcohol consumption (p<0.001 for all CF) and total cholesterol (p=0.042 for memory scores; p=0.001 for letter cancellation task) had positive relationship with CF indices, waist-to-hip ratio (p=0.002 for memory scores, p=0.038 for semantic fluency), level of plasma glucose (p=0.002 for memory scores, p<0.001 for letter cancellation task) and smoking (p<0.001 for letter cancellation task) had inverse relationships with cognition.

Conclusion

Our results show that metabolic risk factors (systolic blood pressure, plasma glucose, waist-to-hip ratio) and smoking had inverse relationship with CF indices in both sexes, and the level of blood lipids (total cholesterol and high-density lipoprotein cholesterol) and frequency of alcohol consumption (more pronounced in women) had positive associations with cognitive domains. These associations were independent from age. In multivariate analyses, some of these correlations were attenuated, and most associations were at least partly mediated by education. These findings highlight the importance of managing CVD risk factors to prevent cognitive decline.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Russian Foundation for Basic Research (20-313-90016),Russian Academy of Sciences (AAAA-A17-117112850280-2)

EEG Alpha-Rhythm-Related Changes in BOLD fMRI Signal in Neurofeedback Training

Interaction of EEG and BOLD brain activity was studied in subjects during EEG-biofeedback training course (20 sessions). Healthy male subjects aged 20-35 underwent a training course of sound-reinforced upregulation of alpha- (20 participants) or beta-activity (9 participants). Pretraining, intermediate (after 10 sessions), and post-training fMRI-EEG recordings were conducted in resting state and during the participants' attempts to upregulate the power of target EEG activity. Regression analysis was carried out on three sessions in total; the main changes in BOLD signal connected with alpha rhythm power were related to the subjects who performed alpha training "good enough" (were able to increase alpha power at least at one stage). Maximum changes in BOLD response connected with alpha rhythm power were observed in the form of deactivation at T8 lead in the right hemisphere, and at F7 in the left hemisphere, and involved middle frontal gyrus, triangular part of inferior frontal gyrus, superior temporal gyrus, parietal lobule, and insula. The identified areas correspond to the executive control network (ECN) and anterior salience network (ASN).

Prospects of Synchronous fMRI-EEG Recording as the Basis for Neurofeedback (Exemplified on Patient with Stroke Sequelae)

Synchronous fMRI-EEG mapping of cerebral activity in stroke patients made it possible to implement neurofeedback, a novel and promising therapeutic technology. This method integrates a real-time monitoring of cerebral activity by EEG and fMRI signals and training of the patients to control this activity simultaneously or alternatively via neurofeedback. The targets of such cerebral stimulation are cortical regions controlling arbitrary movements (Brodmann area 4), whereas its aim is optimization of activity in these regions in order to achieve better rehabilitation of stroke patients. The paper discusses the methodical details, advantages, and promise of bimodal neurofeedback treatment.

Dynamics of Interactions between Cerebral Networks Derived from fMRI Data and Motor Rehabilitation during Stokes

The connections between large neuronal networks were analyzed in 12 patients with ischemic or hemorrhagic strokes and hemiparesis included in the course of the interactive brain stimulation in the area of the primary motor cortex by the analysis of independent components of fMRI. The results obtained in 3 patients are presented. Desynchronization of the visual networks with each other and with the motor networks as well as positive dynamics in Rankin scale and box and blocks test were observed in the patients. These data attest to a decrease in the importance of visual control during movements and probably on partial restoration of prioperception. The important role of interactive brain stimulation and network analysis of fMRI data in neurology are discussed.

Dynamics of fMRI and EEG Parameters in a Stroke Patient Assessed during a Neurofeedback Course Focused on Brodmann Area 4 (M1)

A course of interactive stimulation of primary motor cortex (Brodmann area 4) in the brain of a stroke patient resulted in recovery of locomotion volume in the paretic extremities and in improvement of general health accompanied with diverse changes in cerebral activity. During the training course, the magnitude of response in the visual fields of Brodmann areas 17 and 18 decreased; in parallel, the motor areas were supplemented with other ones such as area 24 (the ventral surface of anterior cingulate gyrus responsible for self-regulation of human brain activity and implicated into synthesis of tactile and special information) in company with Brodmann areas 40, 41, 43, 44, and 45. EEG data showed that neurofeedback sessions persistently increased the θ rhythm power in Brodmann areas 7, 39, 40, and 47, while the corresponding powers progressively decreased during a real motion. Both real motion and its virtual sibling constructed by interactive stimulation via neurofeedback were characterized with decreasing powers of the EEG β rhythm in Brodmann areas 6 and 8. The neurofeedback course decreased the coherence between the left Brodmann area 6 and some other ones examined in α and θ ranges. In the context of real motions, the coherence assessed in the EEG β range generally increased. Overall, the EEG and fMRI parameters attest to growing similarity between the moieties of functional communications effected in real and imaginary movements during neurofeedback course. The data open the vista for interactive stimulation to rehabilitate stroke patients; they highlight the important role of Brodmann areas in rearrangement of the brain in such patients; finally, the present results revealed the "common nervous pathway" that can be used to restore the capability for imaginary and real movements by a neurofeedback course after stroke.

Synergetic fMRI-EEG brain mapping in alpha-rhythm voluntary control mode

For the first time in neurobiology-related issues, the synergistic spatial dynamics of EEG and fMRI (BOLD phenomenon) was studied during cognitive alpha biofeedback training in the operant conditioning mode (acoustic reinforcement of alpha-rhythm development and stability). Significant changes in alpha-rhythm intensity were found in T6 electrode area (Brodmann area 37). Brodmann areas related to solving alpha-training tasks and maximally involved in the formation of new neuronal network were middle and superior temporal gyri (areas 21, 22, and 37), fusiform gyrus, inferior frontal gyrus (areas 4, 6, and 46), anterior cingulate gyrus (areas 23 and 24), cuneus, and precuneus (area 7). Wide involvement of Brodmann areas is determined by psychological architecture of alpha-rhythm generating system control that includes complex cognitive activities: decision making, retrieval of long-term memory, evaluation of the reward and control efficiency during alpha-EEG biofeedback.

[Models of the dynamics of temperature-myographic feedback]

The goal of this work was to perform statistical analysis of experimental trajectories of temperature-myographic BFB training. Approximation of signals was implemented using fractional-linear functions. It was found that the number of approximation functions decreased with increasing number of sessions. Moreover, if the number of approximation functions was large enough, it was possible to find the asymptotic behavior of monitored signal with the help of initial values of the signal. It means that it is possible to reveal the potentialities of patients during 3 or 4 sessions of training. Estimation of the time interval of active work showed that there were two various laws for values of temperature and values of myogram: for the first monitored variable, power law; for the second variable, exponential law. But for both monitored parameters the constants were positive, which meant that there was a minimum of time interval for the active "work" for every patient. Correlation analysis (i.e., analysis of autocorrelation and cross-correlation functions) of temperature and myogram signals showed that there was a correlation between monitored parameters. It means that for both signals we can consider both positive and negative time lag dependence between values of temperature and myogram. Statistical analysis of signal behavior made it possible to construct a phenomenological model of temperature-myogram BFB-training, which comprises the basic parameters of patients. With the help of the model it is possible, in particular, to calculate the sojourn time of system at any part of the phase plane. This characteristic can be used as an integral estimation of the efficiency of BFB-training.

[A two-dimensional statistic method for analysis of patient strategies in biofeedback mode]

Analysis of experimental trajectories in temperature-myographic BFB-training is considered. Analysis of point density on the phase plane (first of all, the states of extreme density points with respect to some basic thresholds) makes it possible to determine the main tendencies in the development of the training process. It also provides an opportunity to obtain a qualitative conclusion about the efficacy of BFB-training. There are three different ways for analysis of experimental points. The first way consists in constructing a general (or integral) picture, which can be obtained by reconstructing the point density for all experimental points measured during a single session. The integral picture shows the number of density peaks and their position on the plane, the sojourn time of the system at one or another part of the phase plane, etc. The second way is the analysis of time series of density values during a single session of training. The first density value corresponds to the basic state of the patient. Analysis of the density dynamics makes it possible to determine the character and tendencies of the strategies used by the patient during the session. The third way is the analysis of time series of integral pictures, which can be obtained upon finishing all training sessions. It provides an opportunity to draw a final conclusion about the efficacy of training in general. The analysis made it possible to divide the group of experimental trajectories into several subdomains. The first subgroup contained the trajectories corresponding to BFB-training based on both monitoring parameters (temperature and myogram). The second and third subgroups contained the trajectories corresponding to BFB-training based on one or another monitored parameter. The last group contained the trajectories used without success.