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Aging in Neuroscience : How brain's abilities decline over time

Introduction


The process of aging is defined as the decline of physiological functions of living animals, which is crucial for survival and fertility. For humans, aging often leads to hearing loss, dementia, back pain, and multiple chronic diseases. In this article, I would like to focus on the cognitive aspects of human aging. The evolution in technologies allowed neuroscientists to establish new measurements and techniques to identify the shift in cognitive ability when aging. The following two subtopics are written after reading “Cognitive Aging: A Primer” by Anek Belbase and Geoffrey T. Sanzenbacher, published in November 2016.


Key techniques to measure the shift in cognitive ability aging


Number of technologies are available to examine cognitive abilities at a certain period of aging. Brain imaging techniques like Magnetic Resonance Imaging (MRI), Computerized Tomography(CT), EEG, and MEG can directly scan the brain and localize the origin of cognitive activity. However, measuring the change in cognition due to aging requires different methods, as they are examining the changes over the life cycle. The two fundamental study models are cross-sectional studies and longitudinal studies.


Cross-sectional studies compare and contrast the cognitive performance of people with different ages concurrently. One of the advantages is effective management of study.  However, the study’s accuracy can be degraded as there are many factors that can intervene. For instance, people who are younger might have received better education or nutrition. This makes simultaneous comparison inaccurate, as it is difficult to estimate how cognitive ability will change for young age participants. 


Longitude studies compare the same individual’s cognitive performance over time. Although longitude studies do not have the same problem as cross-sectional studies, this method also includes risk factors. The study can be extremely expensive, and repetitive assessments during the procedure can lead to enhancing results in the unintended way. Lastly, the study can have irregular conclusions as the participant can make different decisions in the test. 


However, these problems allied with these study methods can be resolved through applying statistical approaches. For example, for cross-sectional studies, we can divide the groups based on their education level or financial background to have a more effective comparison. Furthermore, for longitude studies, scientists can rather focus on how an individual showed cognitive enhancement after multiple practices. The graphics below are the examples of statistical adjustments to effectively measure the changes in cognition as people age. 




Continued developments in experiment techniques allowed researchers to identify new areas of aging in neuroscience. Scientists have now figured out that individuals lose neural matter as they become old, and its process accelerates when they are close to death. The loss in neural matter has a distinctive pattern, as the loss initiates from the back and outer section of the brain, to the front and inner section of the brain. The brain with significant loss in neural matters leads to having a lack of neuro-transmitters. This ultimately leads to poor concentration, state of being vulnerable to stressful situations, and behavioral disorders.  


The definition of cognitive ability can be interpreted in two ways: the possess of knowledge and the gain of knowledge. Former is referred to as “crystalized knowledge” and the latter is referred to as “fluid intelligence”. Distinguishing two aspects of cognition is important before understanding a shift in cognition when aging. 




Discoveries from the research


The researchers have concluded that starting in 30s and 40s, people commonly start to experience a decrease in reaction speed and parts fluid intelligence. In their 50s and 60s, the majority of people experience a perceptible decline in fluid intelligence. However, crystalized knowledge, the ability to absorb new knowledge, remains in relatively stable condition even for those in 70s and 80s who did not experience any exterior damages to their brain.


People in their 50s or 60s can still be productive in the working environment, as there are no studies that significantly support the idea that age-related productivity decreases in society. However, in these age groups the decline in reaction speed will be examined when handling complex situations or making time sensitive decisions.


Conclusion


In conclusion, as people get old, they experience functional and structural decline in their cognitive ability. Advancements in neuroimaging technologies, human biology, and research methods are now helping to identify detailed shifts in cognitive health. The discoveries that are discussed in this article emphasizes the importance of making strategies to cope with our cognitive health. Understanding the basic principle of an aging brain can help individuals to prepare for the future. More importantly, these researches can help society to better utilize the experience and knowledge of the old people in productive roles. 




References 


  1. Belbase, A., & Sanzenbacher, G. T. (2016). Cognitive aging: A primer. Center for Retirement Research at Boston College, 16, 1-9.

  2. Gilbert, S. F. (2000). Aging: The Biology of Senescence. Developmental Biology. 6th Edition. https://www.ncbi.nlm.nih.gov/books/NBK10041/#:~:text=Aging%20can%20be%20defined%20as

  3. ‌Baldwin, C. L., & Greenwood, P. M. (2020). Editorial: Cognitive and Brain Aging: Interventions to Promote Well-Being in Old Age. Frontiers in Aging Neuroscience, 11. https://doi.org/10.3389/fnagi.2019.00353

  4. ‌Teleanu, R. I., Niculescu, A.-G., Roza, E., Vladâcenco, O., Grumezescu, A. M., & Teleanu, D. M. (2022). Neurotransmitters—Key Factors in Neurological and Neurodegenerative Disorders of the Central Nervous System. International Journal of Molecular Sciences, 23(11), 1–24. https://doi.org/10.3390/ijms23115954





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