Until now, data on the age-related dynamics of human cerebral energy metabolism have been limited by the ability to visualize brain metabolism using biochemical mapping methods. Since these methods provide for the introduction of radioactive substances into the body and are more often used in clinical settings, information on gender differences and age-related dynamics of energy exchange is not complete. Analysis of brain SCP is complementary to the concept of cerebral energy metabolism during human development and aging. When comparing the characteristics of cerebral energy metabolism obtained on the basis of measuring the glucose consumption of the brain by the PET method and when evaluating the brain CRC by the SCP method, it should be borne in mind that although both methods reflect cerebral energy metabolism, there are differences between them. Glucose is an energy source that is used by the brain to produce energy, and the pH level reflected in the parameters of SCP is the ultimate characteristic of energy metabolism.
We studied the AMR in 535 healthy people of both sexes aged 2 to 92 years. To exclude cerebral pathology, a neurological and EEG examination was performed. Subjects were divided into groups by gender and age. The calculation of average, variances and standard errors, correlation coefficients was carried out by methods of variation statistics, the nature of the distribution of SCP was estimated using the Wilk-Shapiro method. Statistically significant differences were revealed between the characteristics of the SCP distribution in the groups using one-way analysis of variance. The differences were considered significant at a significance level of p <0.05. SCP spatial distribution of the most conveniently represented by a mapping i .
In the left column is the average age of the subjects. The soft starter color scale is shown in the lower right square.
In early childhood, from 2 to 7 years, high SCP values are recorded. The potential distribution has a domed shape with a maximum SCP in the area of the vertex (crown). The magnitude of the SCP decreases to the frontal, occipital and temporal departments. In the occipital areas, the SCP is higher than in the frontal. Up to 7 years of age, statistically significant interhemispheric differences were found in girls, and the SCP values during this period are higher in the right hemisphere. The differences in this indicator are significant between boys and girls. Parameters of AMR indicate a high level of energy metabolism in children 2-7 years old, which corresponds to data on a fairly intensive consumption of glucose at this age (H. Chugani, 1994). The domed distribution pattern of SCP on the surface of the head with higher values of SCP in the central region compared to other parts of the brain, as mentioned above (Ch. 3), is associated with the organization of the venous outflow system, which makes a certain contribution to the topography of the SCP. It is possible that in addition to a high level of glucose metabolism, brain acidification and, accordingly, an increase in SCP in all leads are affected by the use of ketone bodies as an energy substrate in early childhood .
At the age of 8 – 10 years, compared with the previous age period, no significant changes in SCP are observed in boys. In girls at this age, the SCP in the vertex region increases, interhemispheric differences characteristic of adults are also formed with a higher SCP in the left temporal region. In comparison with boys, girls have a more pronounced domed distribution of SCP with higher potential values in the vertex region in relation to other parts of the brain. During this period, SCP reaches maximum values, which corresponds to the highest level of energetic metabolism detected in the interval from 4 to 9 years according to glucose consumption data .
At the age of 16 – 19 years, compared with the previous age period, in young men, SCP decreases in the frontal, occipital and temporal areas. Girls have a decrease in SCP in the same parts of the brain, except for the occipital region. SCP in the occipital lead is significantly different in boys and girls. Lower values of SCP indicate a relative decrease in energy metabolism at this age, when the level of glucose consumption is almost halved compared to 8 – 9 years.
At an average age of 20–39 years, in men, compared with the youthful period, the SCP value tends to increase in all areas except the central one, where the SCP decreases slightly. A significant increase in SCP occurs in the frontal and left temporal regions, but even in these parts of the brain the magnitude of SCP is lower than in childhood. The presence of interhemispheric difference in the level of potential with a higher SCP in the left temporal region was revealed, as well as the absence of other regional differences in the level of potential. A higher SCP in the left temporal region compared with the right one is apparently associated with a more intense glucose metabolism, which is observed in the associative regions of the left hemisphere . In women, the dome-shaped distribution of SCP is more pronounced with a higher level of potential in the vertex region compared to other parts of the brain; there is a tendency toward greater SCP in the left temporal region than in the right, but the interhemispheric differences are not significant. When comparing men and women, the following significant differences were found: in men, SCP is higher in the frontal region, the potential difference between the left and right temporal regions is greater, differences in SCP between vertex and other parts of the brain are less pronounced. This is consistent with published data on a more pronounced lateralization of the brain in men than in women .
At an older age, 40 – 59 years, compared with the previous time period, no significant changes occur, except for a decrease in SCP in the central lead in men. Differences between the distribution of AMR in men and women persist in the frontal lead and in all associated bipolar leads. In addition, local SCP in the frontal and occipital leads in men is higher, and in the central lead is lower than in women.
In old age, from 60 to 75 years, regional differences in SCP are smoothed out, the potential difference between the temporal regions becomes less pronounced. In women who have a domed distribution of SCP in adulthood, there is a significant decrease in the potential difference between the central region and other parts of the brain (frontal and temporal regions). Significantly increases the SCP in the frontal region. In both men and women, hemisphere differences are not pronounced. Significant differences in AMR in men and women are not observed. A decrease in the potential difference between the head and arm during aging can be due, firstly, to a decrease in the energy metabolism of the brain and a decrease in the formation of acidic metabolic products, and, secondly, to an increase in the potential on the arm in the region of the reference electrode due to acidification of peripheral blood in old age .
In people of senile age (over 75 years old, only women were examined), a further decrease in the level of potential in the temporal areas occurs. SCP in the frontal and central region is significantly higher than in the temporal and occipital regions. Interhemispheric differences in SCP are unreliable. The potential difference between the frontal and temporal regions, as well as the central and temporal parts of the brain, increases .
Thus, according to SCP, as well as computer-aided visualization of biochemical processes, the highest intensity of cerebral energy metabolism is observed in childhood. In the future, there is a decrease in energy metabolism, and in the elderly and senile age, in addition, there is a smoothing of regional differences. The decrease in the differences in SCP in standard leads obviously reflects a decrease in the specialization of the cortex in old age. A decrease in regional differences is observed with aging and in the EEG. Men and women differ in interhemispheric asymmetry of the distribution of SCP, which is more pronounced in middle age men. Differences in local SCP in separate areas were also revealed. In general, however, age-related changes in the intensity of energy metabolism in men and women are approximately the same throughout life.