Executive function (EF) is a cognitive skill that allows individuals to plan, initiate, sequence, and monitor goal-directed behaviors in a flexible and optimal manner to achieve a specific goal.EF disorders are widespread in a variety of neuropsychiatric disorders, including Alzheimer’s disease. Although the American Psychiatric Association identified EF impairment as one of the clinical bases to support the diagnosis of dementia in 1994, EF research has not received the attention it deserves in clinical practice, and this, coupled with the fact that traditional dementia measures are insensitive to EF, has led to a significant underestimation or even neglect of the status of EF impairment in patients with dementia. A growing body of evidence suggests that EF impairment in dementia patients is generalized; EF is closely related to the decline in daily living ability and functioning, and EF. predicts the transition from mild cognitive impairment (McI) to dementia and independently determines the level of care required by dementia patients. Therefore, it is of great significance to emphasize the study of EF in dementia in old age. I. Introduction to EF 1. EF and historical background: as an important cognitive skill, the status and role of EF in the cognitive field is gradually recognized. lu blood in 1969 for the first time on the frontal lobe damage in World War II veterans to conduct clinical EF assessment, and described the frontal lobe system damage resulting in behavioral “procedures, management, adjustment ” changes, suggesting that the frontal lobes are important for EF. Later, A1exander et al. showed that the frontal lobes are linked to the basal ganglia-thalamocortical loop, and that damage to this loop produces “frontal lobe behavior”. It is now believed that EF requires the coordination and interaction of various brain regions. Although EF is primarily a function of the frontal lobe of the brain, damage to other brain regions can result in EF deficits due to the extensive connections between the frontal lobe and other brain regions. EF consists of the following cognitive skills: (1) Attention and inhibition: Attention to task-relevant information and processing, and inhibition of irrelevant information. (2) Task management: refers to switching attention across tasks while processing complex tasks. (3) Working memory: refers to the ability to store and retain information for short periods of time. (4) Monitoring function: refers to updating and checking the content of working memory to determine the next step in the processing sequence. (5) Making plans: refers to planning the processing sequence for a target behavior. 2. Anatomical basis of EF: Brain structures related to EF include the dorsolateral prefrontal cortex, frontal orbital surface, anterior cingulate gyrus, basal ganglia, and cerebellum. There are three loops specifically related to EF. Although each loop passes through different structures, the overall pathways are similar, i.e., excitatory glutamatergic fibers project from the frontal cortex to the neostriatum, and then inhibitory v-monoamino butyric acid (GABA)-ergic fibers are sent out from here to the pallidum or substantia nigra, which in turn project to the specific region of the thalamus; finally, the thalamus sends out excitatory glutamate fibers to return to the frontal cortical area, completing the whole closed loop. area, completing the entire closed loop. The three loops are: (1) dorsolateral prefrontal loop: damage to this loop can affect a variety of higher cognitive functions, such as goal selection, planning, sequencing, task switching, verbal and spatial working memory, self-monitoring, etc. This loop is excited by the Wisconsin Card Sorting Test (WCST). (2) Lateral frontal orbital surface loop: this loop may be involved in situation assessment, behavioral choices, and emotional responses. Damage can lead to personality changes, behavioral disinhibition, and affective disorders. The go/no-go test excites this loop. (3) Anterior cingulate loop: This loop plays an important role in behavioral monitoring and error correction. Damage is characterized by apathy, loss of will, and muteness, etc. The stroop test excites this loop. Therefore, EF is structurally dependent on the integrity of the entire frontal lobe, the basal ganglia arcuate and thalamocortical network, i.e., the frontal lobe system; functionally, any damage that affects the information processing process of the frontal lobe system, regardless of its location or link, can lead to EF damage. 3. Commonly used methods to measure EF: EF includes a variety of cognitive skills, such as planning, attention/inhibition, working memory, etc., therefore, it is difficult to comprehensively evaluate all aspects of EF with a single examination method. The wcsT is considered a possible gold standard for EF screening, but its complexity and time-consuming nature have reduced its clinical value. Royall et al. recommended two bedside screening methods, the executive intenriew and executive clock drawing task, to measure EF impairment. clock drawing task,) to measure EF, which were found to have good reliability and validity and to be easy to administer and suitable for clinical or epidemiologic screening of EF. The ExIT5 consists of 25 items with a score of 50, the higher the score, the better the EF, and the estimated time for completing the test is 10 min. The ExIT5 has a high correlation with the traditional EF test (r=0.90), and is considered to be a valid and reliable tool for assessing EF at the bedside, because it can detect cognitive impairments at a much earlier stage than the Minute Mental State Examination (MMSE). Recently, some scholars have developed reaction time tests on computers, such as the attention network test (ANT) developed by Fan et al, which is also used to measure EF. EF disorders and common dementia in old age 1. Alzheimer disease (AD): AD, as the most common neurodegenerative disease in old age, has a variety of higher cognitive functions, such as cognitive impairment. AD, as the most common neurodegenerative disease in the elderly, has a variety of high-level cognitive impairment, such as memory, language, orientation, visuospatial function, etc., and the memory impairment is considered to be the core symptom of AD and is well known to everyone. As the commonly used cognitive scales in clinical practice do not reflect EF well or even completely ignore EF, EF impairment in AD patients has been greatly underestimated. Studies have shown that AD patients have significant EF impairment, which is highlighted in problem solving ability, collaborative processing of information, and concept formation, etc. It is also believed that memory and EF impairment is the most significant and characteristic of all cognitive changes early in the course of AD, and that the examination of EF, delayed recall, and the ability to learn new knowledge is helpful in the early diagnosis of AD.|collette et al. measured the EF of 20 cases of AD and healthy elderly people in each. Collette et al. measured the EF of 20 AD patients each and healthy elderly people, and the AD patients performed all executive tasks worse than healthy elderly people, and the analysis of the causal factors showed that it was mainly related to two EF regions, i.e., inhibition and the ability to coordinate the storage and processing of information. Some researchers believe that EF impairment and memory impairment may be early manifestations of AD emotion, and that the presence of EF impairment early in the course of the disease may help in the diagnosis of AD I J. However, others believe that EF impairment is present early in the course of AD but is not significant, and that commonly used EF tests Test name Test content Test name Test content Traditional test tools Bedside screening tools caIjfom Card Classification Test (ccsT) cG, P,1 Behavioral Control Disorders Scale (BDs) I Classification Test (CT) cG, wM(v) CIDx wM(s), CG Concept Formation Test cG, wM(v) Control of Oral Connections Test CG, wM(v) Porteus Maze Test (PM) P, wM(s) Conceptual Fluency Test CG, wM(s) Raven’s Reasoning Test (RMT) ‘s Reasoning Test (R’PM) wM(s), CG Exrl25 I, CG, wM(v&s) Stmop Color Word Interference Test I, wM(v) Connecting the Dots Test, Part B I, wM(s) Toy Collage Test CG, wM(s) Frontal Lobe Functionality Rating Scale (FAB) I, cG, wM (v) Hanoi Tower Test wM(s), P, I 90/no-90 I, wM(v) kndon Tower Test wM(s), P, IWCST CG, P, I Note: cG: Concept Formation; I: Inhibition; wM(s): Spatial Working Memory; wM(v): Verbal Working Memory; P: Planned to MMsE scores at 24 or less to be evident Autopsy material revealed that pathologic changes in early AD were visible postmortem in older adults with EF impairments and normal memory and other cognitions, whereas no such pathologic changes were seen in those with normal EFs; postmortem pathologic confirmation of AD in patients with EFs was correlated with prenatal Memory Test scores and overall frontal EF . A study by DeKosky and Sche found that the strongest correlation between pathologic synaptic concentration in the middle frontal lobe and the severity of dementia in patients with AD was found to be the correlation between this pathologic change and both early EF deficits and decreased cerebral blood flow confirmed by single-photon emission computed tomography (sPEcT) testing. 2. Vascular dementia (VD): Patients with VD have significant EF impairment due to the fact that VD usually has extensive lesions that tend to damage structures such as the caudate nucleus, pallidum, thalamus and other structures as well as frontal and subcortical connective fibers, which disrupts the integrity of the EF loop. The relative preservation of memory in patients with VD compared with significant EF decline has led one group to even suggest that EF impairment should be required for the diagnosis of VD, and in fact, EF impairment exists to varying degrees even in stroke patients who have not reached the level of dementia.Pohjasva et al. administered the Comprehensive Neuropsychological Test (CNT) to 486 patients with ischemic stroke aged 55-85 years 3-4 months after the stroke. Pohjasva et al. administered a comprehensive neuropsychological test and evaluated basic and complex living abilities (bADk and CADIJs) in 486 patients aged 55-85 years after 3-4 months of stroke, and the results showed that 40,6% of the patients had EF deficits, and that most of them were elderly, with a low level of education, reduced ability to perform daily living activities, and low MMsE scores, and that most of them had a stroke site in the anterior circulation. Imaging confirmed the correlation between MRI white matter changes and EF impairment in patients with VD. Overall, EF deficits were more pronounced in patients with VD than in AD and differed in the type of impairments. patients with VD were characterized by a lack of inhibition and a reduced ability to process complex information, with a high number of persistent errors in the performance of card sorting tasks, while free recall and cued recall tests were stronger than those of patients with AD; patients with AD showed significant impairments related to attentional shifts and working memory, while the ability to form strategies was relatively preserved …. In terms of memory impairment, Yuspeh et al. found that the VD group’s recollection memory and situational memory were better than that of the AD group, while the ability to reproduce memory content at will was not as good as that of the AD group. 3.Frontotemporal dementia (fmntotemporal dementia,): another type of cortical dementia, clinically characterized by social behavior, personality change and EF disorder. EF disorders can be detected in patients with normal perception, language, and memory, especially when making decisions and changing tasks. Compared with AD patients with cortical dementia, the EF impairment is similar in both, the difference is that FTD patients have more persistent errors and frontal lobe release signs, while memory impairment is more prominent and common in AD. 4, Parkinson’s disease dementia: the incidence of dementia in patients with Parkinson’s disease (PD) is about 12%~30%. patients with PD have EF impairment before developing dementia, which is manifested in sequencing disorder, impairment of execution of planned operations, impairment of stereotyped switching ability, etc. EF impairment is the main neurocognitive mechanism for the loss of ability in patients with PD, and has a predictive value for the risk of conversion to dementia. EF impairment is the main neurocognitive mechanism of capacity loss in PD patients and has predictive value for the risk of transformation into dementia. It is believed that there is a close anatomical connection between the frontal lobes and the striatum, and that dopamine depletion in the striatum leads to dopamine depletion in the prefrontal lobes.5. Progressive supranuclear palsy (PSP): EF impairments are common in PSP, and PsP has more pronounced decreases in attention, task shifting, and categorization abilities than PD. decline is more pronounced. This may be related to the afferent nerve block and dysfunction of the midbrain upward activation system known to occur in the frontal lobe. The significance of EF impairment in the study of Alzheimer’s disease 1. EF is related to the ability of daily life: Since cooking, cleaning, and taking medication on time and correctly in daily life are goal-directed behaviors, these behaviors are naturally impaired when EF is impaired.Auen cogIlitive 1evel assessment (AcLA), which was designed by Allen to assess the ability of daily life, was used to assess the ability of daily life. assessment (AcLA) is based on a series of executive tasks whose points are significantly correlated with an individual’s performance in daily living abilities (cooking r = 0, 83; toileting r = 0, 75; dressing r = 0, 74, etc.)¨o. Veuig meal et al. have linked most of the measures of AcLA to various aspects of EF, such as working memory, response inhibition, etc. EF is also associated with a number of other abilities, such as money management, decision to seek medical care, and self-awareness.Dymek et al. found that the ExI was independent of the Comprehensive Cognitive Rating, and that EXIT25 accounted for 56% of the total variance in an analysis of factors in which the patient understands and accepts the treatment, and 45% in an analysis of factors in which reasonable decisions are made.Boyle et al. examined the EF and the ability to perform daily living tasks in 29 patients with VD, and a multivariate regression analysis confirmed the correlation between the two. EF impairment can predict the transformation of pre-dementia groups to dementia: McI refers to the elderly who have mild memory or cognitive impairment, but have not yet reached the level of dementia.McI often have EF impairment, and their risk of developing AD is about 10 times higher than that of healthy people. Early detection of individuals predisposed to AD development and necessary preventive and interventional treatments can slow progression and improve prognosis. a1bert et al. performed 20 neuropsychological tests on 123 older adults with McI and followed them for 3 years. 23 of them evolved to probable AD, and their scores on 4 baseline tests of memory and EF were significantly worse than the other subjects. chen et al. performed 20 neuropsychological tests on 551 community-dwelling older adults. In a study of 551 community-dwelling older adults who were followed for 1 and 5 years, they found that those who progressed to AD had the most significant decline in EF and memory, and that EF and delayed recall differentiated well between those who progressed to AD and those who remained nondemented at 1 and 5 years. hjasvaara et al. m o In a study of patients with ischemic stroke, they found that EF was useful in the early detection of patients with stroke who were predisposed to the development of dementia and for the prediction of disability in patients with stroke. predict disability in stroke patients. 3. EF determines the level of care required by patients with dementia: there is currently no specific treatment for dementia with degenerative diseases, such as AD, and the treatment of other age-related dementias is not satisfactory. Strengthening the nursing and care of dementia patients can improve the prognosis and quality of survival to a certain extent.Royall et¨ called to examine the correlation between ExIT25, MMsE, physical health status, behavioral problems, etc. and the level of need for care, and the multiple regression analysis showed that the ExI and 125 measurements, which reflect the EF, were in the first place, and independently correlated with the level of caregiving. The use of EF examination helps to screen out individuals who are most in need of enhanced care, which is conducive to the rational use of medical resources and reduces the social burden on families. In conclusion, EF, as an important cognitive skill, has become a current cutting-edge topic in cognitive neuroscience in recent years. Since patients with dementia in old age generally have different degrees of EF impairment, it is important to emphasize the importance of EF examination for dementia patients to understand the status of EF damage for the diagnosis of dementia patients, the assessment of living ability, and prognosis judgment.