Executive Functioning In Alzheimer’s Disease

Prevalence of Alzheimer’s Disease

Discuss about the Executive Functioning in Alzheimer’s Disease.

Alzheimer’s disease (AD) is a neurogenerative disease, progressive and irreversible in nature. Alzheimer is a type of dementia that causes problems with thinking, memory and behavior accounting for 60% of the total types of dementia. It is a form of dementia where there is severe impairment of cognitive abilities and memory loss (McKhann et al., 2011). The symptoms develop with age and are worsened with advancing age. The age of onset is mid 60’s, in the early stages, there is mild memory loss, and with advancement, an individual is not able to respond to the environment. The Alzheimer disease has no permanent cure, however, there are ways to improve the quality of life and to slow the worsening symptoms of the people with Alzheimer (Alzheimer’s Association, 2013).

According to Alzheimer’s Society in United Kingdom, in 2015, around 850,000 people was suffering from the disease and is one of the leading cause of death among the females contributing to 13.4% deaths (Murray et al., 2013). In United Kingdom, the number of people living with Alzheimer is forecasted to increase to 1 million by the year 2025 and by 2051; over 2 million people would have Alzheimer’s disease. Currently, around 36 million people are suffering from Alzheimer worldwide with 28 million people are living with the disease without any diagnosis. According to World Health Organization, Alzheimer is the most challenged global disease and should include this disease in the public health planning (Wimo et al., 2013).

Many risk factors contribute to the disease like age, family history, genetic factors and environmental factors. As the disease is likely to cause in older people, so the people in mid 60’s and above are prone to this disease. Family history is the another risk factor for Alzheimer. The Familial Alzheimer disease accounts for <5% of all cases of the Alzheimer disease with alterations or changes in the specific genes that are passed on from one generation to another (Lambert et al., 2013). The risk genes that have been discovered so far are APP, PSI and PS2 genes. If any kind of alteration occurs in any kind of genes, an individual will have a great chance of developing the Alzheimer disease at an early age. However, some contributing factors increase the risk for Alzheimer disease. The apolipoprotein E-e4 or APOE-e4 is the strongest risk gene that has an impact on the Alzheimer’s disease. Females are more likely to get affected with AD due to their longevity partly (Yu, Tan & Hardy, 2014).

Risk Factors for Alzheimer’s Disease

Memory loss is the main symptom of Alzheimer that disrupts the normal functioning of the brain declining the thinking, memory and reasoning skills. An individual is not able to perform any kind of tasks, confusion in place or time, decreased judgment and changes in personality and mood. AD greatly affect the executive functioning in an individual affected with the disease as one is unable to plan, organize and carry out a set of tasks given in an efficient manner It also affects the ability of self-monitoring, control behavior and cognitive function. According to Ball et al., (2008) a person has impairment in performing the daily life activities with impairment in memory. The executive functioning (EF) is greatly affected in AD and it increases with advancing age. The executive functioning that involves the making of appropriate decisions, paying attention, working memory, focusing on important details, goal accomplishment and finishing of task is greatly affected due to early onset of AD. With the progress of AD, there are changes in the executive functioning affecting the memory, judgment and attention of an individual with response to the environment. The following essay deals with the effect of AD on the executive functioning during the early years.

According to Allain, Etcharry-Bouyx & Verny, (2013) there is impairment of executive functioning in Alzheimer affecting the daily activities and hampering the ability of an individual to cope up with behavior. From the last 15 years, in the preclinical and clinical AD, there is impaired executive functioning and memory that starts with the visuospatial and language deficits. In early AD, executive functioning impairment is present in the patients with cerebra hypometabolism in the frontal cerebral and posterior areas and also in patients having hypometabolism restricted to parietal and temporal cerebra lobes (Albert et al., 2011). According to Visser et al., (2009) in preclinical AD, there is subtle decline in the cognitive functioning and no decline in the daily functioning. The better assessment of executive functioning at the preclinical AD stage could help in developing effective interventions for the proper executive functioning and improving the quality of life of the patients with AD. According to Martyr & Clare, (2012) EF assessment and the activities associated with daily living are the important elements for the AD diagnosis. The results of the study suggested that there is a link between the EF and daily life activities that are greatly affected by AD during the early years.  Before the diagnosis of AD, executive dysfunction is present that is the underlying cause associated with AD. The ability to perform everyday work including driving is affected moderately in the individuals with AD. According to Stopford et al., (2012) the impairment of executive function is greatly associated with the AD. There is deficit in working memory of an individual and considered as a recognized feature. There is frontal lobe dysfunction with impaired executive dysfunction in early onset AD patients that includes deficit in attention, response inhibition and set shifting. The results showed that the posterior hemispheres are involved in the working memory, failure of executive function and attention associated with frontal lobe failure in early onset of AD. 

Symptoms of Alzheimer’s Disease

Arguably, according to Kirova, Bays & Lagalwar, (2015) AD is a neurogenerative, progressive disorder in which there is markedly deficit in working and episodic memory and executive function. The executive dysfunction in early AD patients includes divided attention and poor selective, poor manipulation of skills with failed inhibition of interfering stimuli. During the preclinical stage in AD, there is impairment of executive function during the mild cognitive impairment. The study highlights that the cognitive dysfunction may progress from the mild cognitive impairment to AD with significant executive function changes and working memory. The working memory greatly declines with neurological and behavioral differences that pave the way for the diagnosis and prevention of AD. Arguably, according to Raji et al., (2010) the assessment of executive function in terms of deficit of effective decision-making is more pronounced in mild cognitive impairment than AD. However, there is executive dysfunction in addition to episodic memory dysfunction in early stage of AD emphasizing on executive functioning skills divided or selective attention, manipulation, inhibition and task switching.

According to Marshall et al., (2011) there is impairment of daily life activities that leads to the loss of productivity in early stages of AD. The executive dysfunction is an important contributor that is associated with functional impairment. The study showed that there is a significant relationship between the daily life activities and executive dysfunction associated with early onset in AD. The results showed that executive dysfunction is an important contributor to the impairment of ability to perform daily activities. This relationship is greatly evident in which there is memory deficit in AD with cognitive impairment. With the advancement in age, the executive dysfunction becomes more prominent with complex attention, with visual and verbal organization, working memory, reasoning, planning and judgment. The association between executive dysfunction and impairment in daily activities has clinical significance for the identification of progressing AD. This is helpful in identifying the early treatment options that specifically targets cognitive dysfunction beneficial for the maintenance of patient independence (Robert et al., 2009).

According to Koedam et al., (2010) executive dysfunction is a very common symptom in AD, however, its relationship with other symptoms is difficult in assessing the patients in AD. There is frontal lobe dysfunction in AD patients and executive dysfunction being the important assessment parameter in diagnosing AD. According to Pereira et al., (2008) the executive dysfunction is a manifestation in AD that is common in all the stages, however, it is mild with 64% of prevalence in AD patients. Arguably, according to Reinvang, Grambaite & Espeseth, (2012) executive dysfunction occurs in mild cognitive impairment individuals that includes attention and significant for prognosis. The executive dysfunction is a parameter in patients with mild cognitive impairment that might progress to AD. The changes in the executive function may acts as a cognitive marker for the tracking of the pathophysiological process in AD. The ED has negative influence that impairs the ability to perform and manage the daily life activities and add to the risk for the progression of the disease from mild cognitive impairment to AD.

Impact of Alzheimer’s Disease on Executive Functioning

According to a study conducted by Grober et al., (2008) showed that there is specific behavior and cognitive symptoms associated with executive dysfunction in the AD patients. There are frontally mediated disturbances in behavior that are associated with functional impairment in AD ranging from mild-to-moderate. Arguably, according to Possin et al., (2013) the behavioral variant frontotemporal dementia (bvFTD) patients exhibited a circumscribed pattern of executive function impairment that involves letter fluency, verbal working memory, controlled attention and category fluency. These characteristics act best to differentiate bvFTD from AD and assessment of executive dysfunction support bvFTD strongly. The patients with bvFTD exhibited pervasive pattern in executive dysfunction that includes impairment in verbal and spatial working memory.

According to Esposito et al., (2010) in AD, there is multitasking deficits and lack of initiative in the patients, which have a specific character and is the key to the goal-directed behavior, also called apathy that is defined goal-directed behaviors reduction that are voluntary in nature. According to Wolk et al., (2010) the major ε4 allele of the apolipoprotein E (APOE) gene is the genetic risk factor for AD. The ε4 allele gene carriers have greater effects on the pathology of medial temporal lobe with poorer memory than the non-carriers of the disease. However, the carriers of the APOE gene displayed significant impairment in terms of memory retention, and the non-carriers showed impairment in terms of executive control, working memory and lexical access (Wadley et al., 2008).

According to Bruen et al., (2008) executive dysfunction is greatly associated with apathy and agitation in Alzheimer’s disease. Apathy is linked to executive dysfunction or the ventral frontal area atrophy. This atrophy is also associated with ventrolateral prefrontal cortex (BA47) that may also be associated to the role of the region like social cognition or executive dysfunction. The results of the study conducted by Huntley & Howard, (2010) showed that during the early stages and preclinical AD, when the disease is mild, there is impairment of tasks that assess visuospatial sketchpad function (VSS), however, also requires executive functioning by the centrally located executive system (CES). This paper shows the evidence that the central executive system (CES) is impaired during mild AD and might get affected during the preclinical AD stage. According to Brown et al., (2011) there is gradual decrease in the processing of the speed where that accelerates in incipient dementia. The onset of decrements in speed processing marks the initial onset of mild cognitive impairment in daily functioning; however, there is executive dysfunction and severe daily functioning impairments as AD progresses. However, further research is required to test the above hypothesis (Vaughan & Giovanello, 2010).

Impairment of Executive Functioning in Alzheimer’s Disease

An array of extensive studies has been done to explain the effect of preclinical and early stages of Alzheimer disease on the executive functioning. The risk factors for AD also include gender where females are more likely to get affected with AD than females due to increased longevity. However, there is limited research conducted in determining factors other than age that heightens a female’s chance of developing AD than males. There are also limitations regarding the risk factors that cause AD and impairment in executive function (Mielke, Vemuri & Rocca, 2014).

Most importantly, there is a research gap regarding the measures of executive functions that are associated with AD in the preclinical or early onset stage. Extensive research is required for the identification of good executive marker that can be proposed for studying the extent of executive dysfunction in early AD. There is also a requirement of future research regarding the central executive functioning at earlier stages of AD that can be combined with longitudinal studies. There is also a requirement to learn the processing of executive dysfunction in AD and how people get affected by it. Future research is required to investigate the course and onset of executive function impairment longitudinal to discern that processing speed, memory deficits or atrophy related to onset and progression of executive dysfunction during the progression of the disease (Seo et al., 2017).

References

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Assessment of Executive Functioning in Alzheimer’s Disease

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