Frontal Aging Hypothesis in the Context of Cognitive Aging - Assignment Example

Frontal Aging Hypothesis in the Context of Cognitive Aging 1. Introduction There is considerable amount of evidence regarding age-related changes in cognitive functions in the brain. The purpose of this paper is to evaluate the findings of frontal aging of brain and its effect on cognitive functions by comparing Greenwood’s (2000) study with other studies that estimate aging affect on brain. Greenwood’s (2000) article, ‘The frontal aging hypothesis evaluated’, sheds the light on the cognitive functions and visuo-spatial attention include parietal, occipital, posterior parts (Dumontheil, 2007). The findings and the methods used are reviewed and evaluated. The strengths and weaknesses are outlined according to the findings from other studies. As part of the evaluation, the relationship between visuo-spatial attention and affects of aging is discussed. In addition to this, the effects of lesions in the brain on cognitive functions in the later stages of life found to be important in estimating the aging affects. The affect of age on efficiency of working memory has been reviewed comparing with other studies relating working memory and aging. Regarding this, different studies (Sarah E. Macpherson, 2002 and John Gunstad, 2006) revealed that the healthy aging is associated with deterioration of frontal lobes of brain and altered time estimation. This in turn compared with the evidence about the personal experiences of a man embedded in historical context that can enlighten the recall (Levine, 2003). Thus, the findings of different studies are useful in estimating the affect of aging on brain especially in frontal regions. 2. Different Aspects Affected by Aging The different aspects affected by aging are frontal lobes, cognitive capability, accuracy in decision-making, mental rotation and calculation or estimation that depends on recall of memory (Johnson and Gottesman, 2006). Another factor affected by aging is visuo-spatial attention. This affect is in a different manner to that of cognitive, decision-making capabilities, and was well analysed in Greenwood’s study (Johnson and Gottesman, 2006). As the disruption of central control processes might result in impairment of relevant behaviour, the affect of age on central control processes is a significant factor that estimates the disruption. The updating of working memory and attention capacity are also among the aspects that are observed to be affected by aging and are critically analysed in Greenwood’s (2000) study. 3. Frontal Age Hypothesis Dempster (1992) and West (1996) argued that the prefrontal cortex declines specifically more than the frontal cortex with aging. Adnreasen et al (1996) has concluded that the gender processing has been reported to activate both inferior and temporal frontal areas. Regarding prefrontal cortex, frontal cortex and frontal lobes, Greenwood’s (2000) study is helpful in estimating performance variability in healthy aging. These areas are on the left, while recognition of familiar faces activated only fusifrom gyrus bilaterally. This finding emphasizes the affect of frontal aging on face recognition. The observations of Duarte et al (2007) denote that, the effects of aging on neural correlates of subjective and objective measures of recollection in older adults with high or low overall recognition memory performance. According to Duarte et al (2007)’s study, the results relating the performance variability in healthy aging with different methods of recollection showed the intact performance in older adults if the tests are subjective. This indicates the difference between the response of brain to subjective and objective tests and the consideration of this difference is little in number of studies particularly in Greenwood’s (2000) article. 4. Self Initiated Memory Related with Frontal Regions The contributions of frontal regions for cognitive functions decline in aging. The results of exploration using functional MRI, indicated that they are active in younger adults and under recruited in older adults (Logan et al, 2002). The article ‘The Frontal Aging Hypothesis Evaluated’ of Greenwood analysed this fact by considering the MRI images of individuals of different age groups. However, the lack of selective nature added to absence of spontaneous activity in older adults. This can attribute to the link between selective nature and spontaneous capability, but Greenwood’s (2000) study did not proceed in that way. Instead, it concentrated mostly on MRI results of younger and older adults and observed the lack of activity in L BA 45/47 in older adults compare to younger ones. However, the loss of activation in BA 45, 46, 47 are also observed by Greenwood (2000), but it is not based on MRI tests. It is based on visual and cognitive tests. Older adults are able to recruit left frontal resources to a similar extent as younger adults provided more supportive encoding conditions. The differences in encoding and changes in left and right frontal regions are mentioned by Greenwood (2000). However, MRI results Greenwood (2000) considered the inertia of hemodynamic response, which makes MRI a poor tool in understanding the patterns of intentional word in younger and older adults (Logan et al, 2004). 5. Anatomy Change in Brain due to Aging According to a study (Cyma Van Petten et al 2004), in addition to frontal lobe changes due to aging, numerous aspects of brain anatomy change with advance in age. Petten et al observed the various post-mortem studies and concluded that the weight and volume of brain decreased with the age at the time of death. This observation of post-mortem reports for the people of different ages is not present in study of Greenwood (2000). Instead, it considered the change in brain activation patterns that indicates the effect of age on regional metabolism of brain, which is a more powerful aspect that reveals more about aging affects on brain. Nevertheless, both the studies coincide at a point of brain activation, the difference taken into considerations result in the variation in the outcomes regarding further research (Tisserand and Jolles, 2003). The effect of evolution and sex also play a role regarding the affects of frontal aging. Greenwood considered comprehensive model of brain organisation as proposed by Mesulam in 1981. This resulted in consideration of functional networks involving several regions, which depend on the integrity of myelinated corticocortial connections. This is a good concept about the effects of aging on mind. However, the absence of consideration of sex in aging effects on mind is clear (Bauman and Kemper, 2005). This absence of gender difference is mentioned because the aging factor affects males and females differently according to Joshi and Parle (2006). This is about differences in skills of males and females that are result of human evolution. It further evaluated the effects of aging related to endocrine malfunctions. Hence, the difference in effects of aging on mind in sex is another aspect that needs analysis in the future research. 6. Description of Cognitive Abilities and Affect of Age Perception, memory, judgment, perceptual speed, spatial manipulation and reasoning are part of cognitive abilities. According to Anstey and Low (2004) different cognitive abilities, have different developmental trajectories across the lifespan, while aging. The study pointed out the difference in the change that different cognitive abilities undergo during the aging of an individual. While describing the normal cognitive aging with fluid abilities the large individual differences for decline experienced by individuals and the patterns of decline across different abilities are considered. The age related decline in repetition priming is an important aspect observed in Greenwood (2000) study. This is a reflection of important latent variables used in experiments to show the brain regions affected by aging. It was found that explicit memory is reduced in older people than in the young group. In a different manner, Anstey and Low (2004) discussed the differences between normal changes and dementia. Resistance for dementia or minimising the effects of aging on mind: According to Levine (2004), uncanny descriptions of characters in a novel will enlighten the memories regarding it. However, these memories are also subjected to erosion; it is found that they can be recalled easily in the course of aging when compared to other memories that do not have uncanny descriptions or emotional attachment. This reveals that, even aging persons have unlimited accesses to personal and public information, but a restricted access to events experienced perceptual, cognitive and emotional detail. This is because, the general knowledge and understanding of narrative meaning is preserved and facilitated even in older adults, but the contextual details is best executed in younger adults (Levine, 2004). Whereas in Greenwood’s (2000) study, though this type of difference is mentioned, the study has been concentrated on frontal lobes and autobiographical recollection and brain imaging is not a major consideration. Therefore as per these considerations, Levine (2004) study is a recollection specific in estimating the aging effect on mind while the Greenwood’s (2000) study is a generalised examining of the aging affect on frontal lobes to estimate the effect of working memory on cognitive abilities. 7. Conclusion According to above discussion it has been established that the effect of age is inevitable on frontal lobes of brain and other cognitive abilities and on execution of decisions. The effect of aging on frontal lobes resulted in changes in cognitive capability, accuracy in decision-making, mental rotation, recall of memory and visuo-spatial attention. The effects of aging on prefrontal cortex are more than frontal cortex and they affected the performance variability in healthy aging. The changes in brain anatomy and metabolic activities in brain are due to aging. Different studies mentioned various concepts to estimate aging affects on brain by considering different methods that range from task execution to brain imaging and MRI scan images. In addition to these different cognitive abilities are affected differently due to aging. Greenwood’s (2000) study considered various issues regarding working memory, cognitive abilities and decision-making. However, it is a generalised study and every aspect considered in it needs a specific study to establish the estimated effects. 8 Scope for Further Study As it has been observed that the uncanny descriptions have a substantial effect on resisting the aging effect on mind, the research about the areas that are involved in this aspect need a specific study. The study relating working memory and cognitive abilities is not sufficient and it has to be continued with the brain images while the younger and older adults are performing tasks that involve working memory and decision-making. In addition to these, each aspect that affects and resists the affects of aging on the brain need topic specific study leading to a generalised study that includes all the aspects. References: 1. Adnreasen, N.C., O’Leary, D, S., Arndt, S., Cizadlo, T., Hurtig, R., Rezai, K., Watkins, G, L., Ponto, L. B., & Hichwa, R. D (1996) Neural substrates of facial recognition. Journal of Neuropsychiatry and Clinical Neuroscience. 8: 139-146 2. Anstey, K. J., and Low, L-J. (2004) Normal cognitive changes in aging, Australian Family Physician, 33 (10): 783-787 3. Bauman, M., and Kemper, T., (2005) Neuroanatomic observations of the brain in autism: a review and future directions. International Journal of Developmental Neuroscience. 23 (2-3): 183-187 4. Dempster, F. N. 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