This chapter explains about related studies regarding the relationship between the speed of information processing and short-term memory among the elderly in community. Furthermore, this chapter is also discussing about the previous studies that had been done and the study outcomes.
2.2 Literature review
Ageing is an unavoidable lifelong process where each of the human being will go through starting from the conception, birth, maturity to death. An older or elderly person is defined as an individual who aged from 60 years and above as stated and approved by the World Assembly On Ageing 1982 which being held in Vienna. The number of elderly population in the world is begun to accelerate drastically from decades. As reported in the World Population Ageing 2017, the number of global population who aged from 60 years and above are estimated to be about 962 million in 2017 which is more than twice compared to years back in 80s when there were only about 382 million among the worldwide. Moreover, it is estimated that the number will be doubled in 2050 especially those in the developing countries. Globally, two thirds of the elderly of the world’s ageing population within the developing regions were rapidly growing through years. It was expected that 8 out of 10 of elderly will be living in those developing countries by 2050 (UN, 2017)
Based on the study done by (Aizan Hamid, 2015) in recent years, the prevalence of Malaysia’s ageing population is also experiencing a rapid growth changing like any others developing countries. It was reported that the mortality rates are rising even higher than the fertility rates as it keeps increasing over time thus putting this nation in a short period to be prepared into an ageing nation. It is expected that the older population will be twice in just 23 years from 7% in 2020 to 14% in 2043. It is already showing a rising trends in elderly population starting from 2010 onwards and estimated to be at its peak by the year of 2020 with 69.3%. Furthermore, it was also stated in The Straits Times that Malaysia ageing’s population within the elderly is inevitable. Sooner or later we will be turning into an ageing nation as according to the world’s population statistic, Malaysia comprises above of 9.5 percent of the population where it may only need 25 years for Malaysia towards transcendence country (The Straits Times, 2018).
In addition, a huge number of elderly was found to be associated with the age-related cognitive decline along with the rapid increases of elderly population. In a study by (D Murman, 2015), he stated that the cognitive functions deteriorate over time as human aged that affecting the performance of cognitive tasks such as short-term memory, speed of information processing and executive functions. He also emphasized that declining of cognitive abilities gave a large impact on daily activities itself. The elderly often showing a deficit in short-term memory when performing specific task (Kausler & Puckett, 1979; Salthouse & Babcock, 1991; Wingfied, Stine, Lahar, & Aberden, 1988). There is also declining in speed of information processing in elderly compared to younger adult when performing activity (D Murman, 2015).
Recently, these cognitive declining issues were receiving huge attention from the worldwide. Thus, it was reported that the prevalence of elderly themselves were increasing as well as the older population which are keeping its increasing growth pace which occurring over in every lifespan of normal individual. Moreover, there is an evidence that there was a declining in memory functioning and speed of information processing within the living community along with the increase of age which associated with the fewer years of education, poor health status, and lower activity performance. For an instance, individuals with higher level academics status with good health were found to be still showed cognitive changes even in late adulthood (Christensen, 2001)
Besides that, there is an agreement in the literature about the cognitive functioning which stated that the memory performance declines from early to late adulthood. For example, it was found that the older people experienced difficulty in their ability to recall and recollect event (Grady and Craik,2000).
In a study done by (Geda Y, 2012), it is stated that the respondents were discovered experiencing and having forgetfulness for recent events and future engagements which related to the short-term memory abilities. In a research done by (Lu and Haase, 2009), with 11 participants whom are the caregivers of the parents were interviewed about the changes of the parents, the result shown that each of the caregivers stated about the significant memory loss which was impaired in the short-term memory ability. The same interviewer is used for each respondent to make sure the validity of information given. As for the gender differences, there is no significant gender effect against short-term memory as both female and male performed equally in STM tasks using Test of Memory and Learning (TOMAL) (Lowe, 2003).
For an instance, in a study by (Pertzov, Heider,Liang and Husain, 2015) which exploring the visual short-term memory (STM) in object identification and localization among healthy ageing individuals. This study involved 139 participants which consist of 77 females and the remaining 62 were males within the age range from 19 to 83 years old. Based on the object identification test that was done towards the participants, the result showed that the younger adults perform better than the older ones. Longer delay time resulting even worsen performance in object identification compared to short delay time (F(1, 135) = 21.4, p < .001 and decreased in performance when the number of items increase rather than one item (F(1, 135) = 331.1, p < .001. Whilst, the result for the object localization showed that the older adult group perform less better than younger group in both localization error and swapped localization error. Hence, it was concluded that the older age group decrease in performance of visual short-term memory.
Furthermore, ageing process was found to be related with the changes pattern in the functional and brain structural network as age increase. Declining in short-term memory was found to be associated with the medial temporal lobe (MTL) which located at the hippocampus within the brain region. Several studies argued that the STM tasks required binding of few elements such as in object localization which are dependent to the medial temporal lobe (MTL) (Das et al., 2015). While, in a study by (Watson et al.,2018), the speed of information processing ability was found to be related with the frontal changes in gray and white matter in brain regions. In addition, in the previous study stated that the integrity of specific white matter tract can mediate age-related slowing in cognitive processing speed (Lu et al.,2011).
Even though there’s a few of studies have been discussing about the short-term memory issue almost for decade, there’s still a big confusion in between the definition of short-term memory and working memory abilities. Based on the study done by the (Aben Bart, Stapert S and Blokland A, 2012), which discussing about the distinction in between the short-term memory and working memory.
Short-term memory is defined as ability to hold and process new information for a short-period of time temporarily as stated by George Miller (Lutz S & Huitt W, 2003). It has limited duration as it can only hold the information for about 15 to 30 seconds according to Atkinson and Shriffin, 1971. While for the capacity of short-term memory, a normal individual only able to recall maximum of approximately seven plus or minus two items at one time. Briefly, the information registered through the environment stimulation will be send to primary sensory where it would be stored then changed into a short-term store. The information might stayed and be stored into a long –term memory or leaved the system ( Stern Y and Brickman, 2009) as stated in the Encyclopedia of Neuroscience.
As for information, working memory is defined as the system that involving a few processes, where the information is temporarily stored and manipulated, in performing complex tasks such as learning, reasoning and comprehension (Lane D, 2014). Whilst, according to a model developed by Baddeley and Hitch, 1996, working memory is separated into three system which need each other in order to carry out whether simple or complex tasks. First system is known as the “phonological loop” which helps to restore the verbal and auditory information, while for the second system is called as the “visuospatial sketchpad” involving the visual and spatial information and the last system is the “central executive”.
For an instance, there’s been a few studies that emphasizing the relationship in between the working memory and speed of information memory instead of the relationship in between the short-term memory and speed of processing information. But, only a few study done that focusing on relationship in between the short-term memory and speed of information processing topics. For an instance, a study by (Lengenfelder J, et.al, 2005) entitled “Processing speed interacts with working memory efficiency in multiple sclerosis” focusing the multiple sclerosis (MS) population. In this study, 43 person diagnosed with multiple sclerosis were used as the participants and 32 healthy individuals as the controlled group. A VT-SAT computer task was used to assess the neuropsychological abilities with 2 trials. Based on the result, the multiple sclerosis groups showed significantly poorer performance in both trial, trial 1 and trial 2 rather than the healthy controlled group. It was found to be an association in the relationship in between the working memory and speed of information processing as poor working memory performance influenced by the poor speed of information processing where the multiple sclerosis able to finish the task normally as the healthy group indeed, but need more time for completing.
As for the study that discussing about the relationship in between the working memory and speed of information processing among the schizophrenia or schizoaffective disorder by (Cassetta B and Goghari V, 2016) stated that there is association in between both of the working memory and speed of information processing as well. This randomized controlled trial study included a number of 81 respondents diagnosed with schizophrenia or known as schizoaffective disorder were recruited. They were examined with three types of training which was a processing speed training group, working memory training group and no training group where it will be done for 30 minutes per day, 5 days in a week for a total consequence 10 weeks at home. Based on the result, there is association in between the two components, working memory and speed of information processing as well in schizophrenia individuals. Based on the previous study, not many of them were emphasizing on the relationship of short-term memory and speed of information processing. That is why, conducting this study is needed due to lack of recent study regarding this issues.
Speed of information processing is generally refers to reaction time of how faster an individual able to finish or complete a task with a reasonable accuracy. For an instance, an individual may able to learn the new skill equally, but differs in term of how quick and accurate for them to perform it. (Lichtenberger ; Kaufman, 2012) as found by Lane D,2014 in his article regarding the processing speed and working memory. Based on the research by (Lu et al.,2011) that focusing on the processing speed emphasized that the speed of information processing declining along with the age among the healthy elderly. Furthermore, a multiple sclerosis (MS) and schizophrenic patients were found to be having a slowed speed of information processing which resulting in slowed task performance. It was also stated in that the cognitive processing speed slowed significantly with the increases of age due to structural and functional changes (Gottsdanker,1982; Salthouse, 2000; Salthouse,2009, Tombaugh, 2004; Schaie,2005; Willkinson ; Allison,1989). As for the gender differences according to (E Roivainen,2011) discussing about the gender differences in processing speed resulted that there is a significant difference between male and female as male tends to react faster on the task involving motor response compared to female who respond faster in term of language and reading skills. For example, the male sprinters able to finish his race in shorter time compared to female sprinters (Duffy, 2010). She suggested that the age and education also one of the main factor that affecting the speed of information processing as well as the participants with 16 years of education scores higher rather than the one with 8 years of education since it left a strong impact on cognitive skills.
In a recent study by (Litvan et al,) that is conducted in order to measure the speed of information processing among the people in multiple sclerosis. This study involved sixteen respondents (N=16, 7 men and 9 women) with multiple sclerosis diseases where they were evaluated with Paced Auditory Aerial Addition Task (PASAT) which comprises of random series of number from 1 to 9 as a research tool. As a result , there is a significant difference in speed of information processing among the individuals with multiple sclerosis .
Speed of information processing was found to be deficit within the individuals whose having multiple sclerosis as emphasized in a study. A Paced Auditory Serial Addition Test (PASAT) is a research tool is used to measure speed of information processing which comprised into two Auditory Threshold Serial Addition Test (AT- SAT) and Visual Threshold Serial Addition Test (VT- SAT). Using the PASAT, 81 individuals with multiple sclerosis were used as a respondent. As a result, there is a significant difference in the speed of information processing within the multiple sclerosis group for AT- SAT and VT- SAT (F(1, 115) = 6.22, p = 0.014). But there is no significant difference was found for performance accuracy among the participants (Demaree et al.,1999).
As well as stated in a study by (Carlozzi et al., 2015) on speed of information processing which 4,859 respondents were recruited as a sample age range from the 3 to 85 years old using the NIHTB Pattern Comparison Processing Speed Test as research tool to evaluate the processing speed. This test acquired the respondents to identify two different visual patterns whether the “same” or “not the same”. According to the result, it showed that the adolescent and adult groups perform better compared to the elderly group whereas it can be concluded that there is declining in speed of information processing as age increase.
As a matter of this issue regarding the declining of cognitive functioning, structural brain changes were also found to be highly related to this where white matter hyperintensities (WMH) and hippocampal volume lead to decreasing of processing speed ability and executive functioning. 81 non-cognitive impairment elderly were recruited as the participants which age range from 75 to 89 years old. As a result, lower in hippocampal volume loss with the increasing in WMH lead to poor in speed of information processing and executive function (Kathryn V. Papp et al., 2013).
As mention above from the previous research, each of the speed of information-processing and short-term memory was found to be decelerating along with the increasing of age neither among the healthy elderly. But, the question is, is there any related association between the speed of information processing and short-term memory?
In one of the study done by (Killane et al, 2014) among the community-dwelling older people in performing gait task, there is significant association between both of these as poor in short-term memory lead to poor speed of information processing. 8174 of participants were assessed by either single cognitive or motor task or performing both as dual gait tasks where for cognitive task client was asked to recite alternate alphabet while walking at normal pace as for motor task, they were needed to carry a glass filled of water for 2.5m distances pathway. The resulted show that there was significant difference in short-term memory and speed of information processing in both single and dual gait tasks. In another research by (Fry and Hale,2000), it also stated that as the speed of information becoming real faster (Hale,1990; Kail, 1991) then capacity of the short-term memory will increases as well (Dempster, 1981).
Yet, it is still lack of studies is done regarding this issues to determine whether if it is any relationship between the short-term memory and speed of information processing. Hence, that is why a further study must be conducted in order to identify if there is any correlation in between both the short-term memory and speed of information processing among the elderly in community.