Multi-Component Intervention: Comparison
Please note this is a comparison between Version 2 by Peter Tang and Version 1 by MADHUCHHANDA MOHANTY.

Subjective cognitive decline (SCD) is one of those significant concerns faced by older individuals. Though it is predominantly self-reported, it is not an event that should be overlooked, considering its significant association with cognitive disorders like Alzheimer’s disease, mild cognitive impairment, and so on. This makes it imperative to find ways to manage the event to enhance the cognitive performance of older adults and/or suppress the rate at which cognitive decline results in impairment.

  • subjective cognitive decline
  • Alzheimer’s disease
  • multicomponent nonpharmacological intervention
  • physical activity
  • cognitive training
  • diet
  • social activity

1. Introduction

The elderly population is increasing rapidly worldwide, and so is the number of older adults having age-related cognitive decline, as well as dementia. Ageing is associated with a decline in cognitive functions that are critical to independence, social engagement, and quality of life. This decline in cognitive function, if not checked, can advance to clinical cognitive decline and in turn, can progress to dementia [1,2,3][1][2][3]. As the proportion of people aged over 65 years continues to expand, it is estimated that, by 2050, dementia could affect some 106.2 million people globally [4]. Age-related cognitive decline affects far more people than dementia [5]. Most dementias are caused by Alzheimer’s disease (AD), and there is no cure available for AD or other types of dementia [6]. Therefore, it is important to develop an intervention to reduce the number of dementias. It has been discovered that pathophysiology associated with AD starts ten years or more before objective cognitive impairment that may be assessed using standardized neuropsychological instruments [6,7][6][7]. The seven risk factors for dementia are diabetes, hypertension, obesity, smoking, depression, lower education, and physical inactivity. It is estimated that a 10–25% improvement in all seven risk factors could potentially prevent up to 1.1 to 3.0 million cases of AD worldwide [8]. Dementia prevention primarily focuses on reducing the risk factors and enhancing the lifestyle of the middle-aged population at very early stages before the onset of symptoms and secondarily by trying to reduce or halt the progression of a disease once the symptoms start to appear [8,9][8][9]. The potential early symptomatic manifestation of AD is subjective cognitive decline (SCD), a pre-clinical stage of AD. Researchers were motivated to turn their attention to the preclinical stage of AD when several earlier clinical trials of treatments in dementia or mild cognitive impairment (MCI) stages failed [10,11][10][11]. SCD is a cognitive state that lies between objective cognitive impairment and intact cognition [12].
Subjective cognitive decline (SCD) is the self-reported experience of worsening memory or cognition or more frequent confusion or memory loss. The distinction cannot be made by cognitive testing, because individuals with SCD and cognitively unimpaired individuals without SCD are, by definition, objectively unimpaired, and they both perform above the cut-off for impairment in cognitive tests [13]. Subjective cognitive decline (SCD) represents a significant concern among the ageing population, and it is more often than not self-reported, although it is also possible for an informant to report about another person having SCD based on specific observations [14]. Some of the most common symptoms of SCD are depression, anxiety, and cognitive complaints [14,15][14][15]. Furthermore, an individual with SCD may also experience a heightened level of stress, anger, and fear of dementia. The prevalence of SCD is around 18–55% globally [16], despite the unavailability of any concrete objective measure to ascertain the decline [17]. The prevalence figure comes even in the face of how the cognitive tests of the majority of the individuals’ nursing worries over SCD have often turned out within the normal (healthy) range [12]. Besides, it has been widely acknowledged that people with SCD have better access to cognitive reserve and also exhibit considerably preserved current cognitive function [18]. There is also a higher probability for older adults with SCD show neurodegeneration and other Alzheimer’s disease biomarkers than others without SCD [19,20,21,22][19][20][21][22]. As no disease-modifying treatment has been found to be effective in the treatment of cognitive impairment and Alzheimer’s disease, researchers are focusing on non-pharmacological treatment. The dementia research community has increasingly concentrated on multidomain therapies that address numerous risk variables at once in order to give a larger possibility of achieving observable improvements during study periods [23]. The emphasis is on close attention to the preclinical phases of cognitive disorders in a bid to ensure early detection that would further boost the chances of creating suitable prevention and interventions that adequately take care of such cognitive disorders [24].

2. Management of Subjective Cognitive Decline

The effective management of subjective cognitive decline is regarded as an incumbent need considering the rising elderly population across the globe, and the significant association between SCD and the heightened risks of pathological ageing [25]. Managing SCD does, however, come with specific challenges, as there have been contradicting outcomes regarding the effectiveness of certain non-pharmacological or even pharmacological interventions. The risk factors for SCD identified are older age, female sex, anemia, thyroid diseases, lack of physical exercises, living alone, minimal anxiety symptoms, and daytime dysfunction [26]. Interventions that could slow cognitive ageing or lower the risk of dementia are promised by the idea of cognitive reserve. Many recent studies have focused more intently on lifestyle characteristics, intellectually stimulating behaviors, and personality aspects, while the original observations focused on clearly measured variables like education or occupational accomplishment. Overall, they show that cognitive reserve is not a constant entity but can change throughout the course of a person’s lifespan depending on exposures and actions and that contributions to reserve originate from a variety of sources. It is encouraging to think that lifestyle adjustments made even later in life may provide protection against dementia or age-related cognitive impairment. Despite this intriguing possibility, careful research will be necessary to turn this concept into a workable solution. Such research would provide useful details both about the combination and timing of activities that may lead to maintaining or improving cognition and more successful ageing [18].

3. Multi-Component Intervention

It is believed that the probability of gaining more satisfactory outcomes on cognitive performance will be boosted as multitask activities are engaged [27]. Furthermore, there has been evidence that multi-component non-pharmacological interventions are more effective than single-component interventions, since the former will bring about positive impacts in more than one domain [28]. That said, the perceived economic advantages offered by non-pharmacological interventions for the management of SCD makes people see them as a good alternative, even though studies in this direction are hard to come by [29]. A review reported that multi-domain lifestyle intervention strategies effectively delay and/or prevent cognitive impairment in healthy older individuals [30]. Nevertheless, people should start performing them regularly as early as midlife, so that they could have an impact on cognitive function in later life. The results confirm that diet/nutrition, cognitive training, and physical exercise interventions are particularly effective in this sense [30]. This opinion is currently supported by the European Dementia Prevention Initiative, an investigator-initiated initiative of several groups involved in ongoing dementia prevention trials in Europe [31]. Since 2017, this initiative has been spreading to other continents and the reduplication of European projects e.g., the Finnish Geriatric Intervention Study to Prevent Cognitive Impairment and Disability (FINGER), have been undertaken in Asia, USA, and Australia [32].
The benefits of physical activity for brain health have been linked to increased cognitive performance, lowered anxiety and depression risk, better sleep, and higher quality of life [33]. Physical activity may also be a promising intervention in the cognition of included patients with dementia and moderate cognitive impairment (MCI), according to recent meta-analyses of randomized controlled studies [34,35][34][35]. This evidence was also supported by cross-sectional investigations, long-term observational studies, and prospective intervention trials [36,37][36][37]. While a large number of studies have examined biomarker data to identify the underlying processes by which physical activity (PA) safeguards the health of the brain in healthy individuals and animal models, a 6-month resistance training program improved the activation of three critical cortical areas, i.e., the right frontal pole, the right occipital-fusiform gyrus, and the right lingial gyrus, during an associative memory test in a Canadian RCT involving 86 female participants with MCI [38]. An Australian SMART (Study of Mental Activity and Resistance Training) trial, involving 100 older people with MCI and six months of progressive resistance training, was linked to enhanced global cognition, a slowed progression of white matter lesions on MRI, and improved global cognition [39]. Finally, a 6-month aerobic PA intervention improved global cognitive function as measured by the ADAS-Cog, physical fitness as measured by the 6-min walking test, and diastolic blood pressure compared to usual care plus education in a Canadian RCT with 70 older adults with mild vascular cognitive impairment [40].
Cognitive training has become one of the most popular non-pharmacological interventions, primarily due to its effectiveness [41,42][41][42]. However, some studies have shown this particular intervention to bring about no improvement in cognitive performance [43]. Specifically stating, cognitive training has been reported to result in a significant increase in the volume of gray matter in the brain, even as cortical volume expansion was also achieved. The probability of SCD patients showing improvement in verbal recall increased [44]. Lifestyle interventions hovering around nutrition, exercises, and one or more component(s), such as behavioral modification, counseling, and so on [45], have also been utilized as a viable multi-component intervention, and this has reportedly caused the rate of cognitive decline to be slowed down, thus allowing elderly individuals to attain some degree of independence [46,47][46][47].
The Mediterranean diet is one dietary pattern that has shown promise in recent studies (MeDi). The MeDi is a diet that emphasizes a primarily plant-based diet with a high intake of fruits, vegetables, nuts, and legumes; a moderately high intake of fish; a low intake of red meat; and the primary source of fat being extra virgin olive oil [48]. The MeDi has been proven to directly reduce the risk of dementia through decreased levels of amyloid plaques [49], brain atrophy [50], and structural connections, as well as indirectly through changing cardiovascular risk factors and brain atrophy [51]
A substantial body of literature is developing that supports the notion that frequent social activity may help to prevent or delay cognitive decline in old age. Social activity could also provide meaningful social roles and a sense of purpose in old age [52], which could have direct neurohormonal influences on the brain, including the reduction of the stress response. Finally, although we controlled for physical activity, social activity also requires a degree of physical activity above and beyond regular exercise and walking, which could enhance cardiopulmonary fitness, leading to vascular changes in the brain and cerebral oxygenation that might protect against neuropathology [53].


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