## 4 Discussion
Thus, the observed improvements in memory may be due to the supplementation, or the combined effect of PreCODE with NeuroQ, rather than lifestyle modification alone; however, this hypothesis needs to be examined in a placebo-controlled double-blind study. Impairments in executive function, cognitive flexibility, and working memory specifically are associated with mild cognitive impairment [60; 61]. Therefore, improvements in these domains in a population at-risk of cognitive decline are a central component of cognitive performance and highly relevant for everyday activities in this population. Executive function, commonly referred to as problem solving and reasoning, is [62] relevant to a population with mild cognitive impairment [44]. In the current study, this cognitive flexibility was improved by 11% at Day 90. As both inductive reasoning and mental flexibility begin to decline after age 45 and 70, respectively [1], this intervention may offer improvements to the cognitive domains that are negatively affected by natural aging. The collective improvements observed in the QoL, and life habits of the participants are conducive to a healthy lifestyle, speaking to the breadth of the potential effects of PreCODE with NeuroQ, far beyond improvements in cognitive performance itself. Cognitive complaints are associated with higher rates of depression, anxiety, and stress, and decreased QoL and mental wellbeing [63; 64]. Depressive symptoms are associated with an increased risk of developing cognitive impairment or dementia [65]. This intervention resulted in a 56% reduction in the depression score at Day 90, potentially decreasing the risk of developing cognitive impairment or dementia. There was an 11% reduction in participants reporting minimal or mild depression on the PHQ-9. Significant improvements in energy, general health, pain, physical functioning, and role limitations due to physical health were reported on the QoL. The combined intervention of lifestyle modifications and supplement increased the QoL by greater than previous reports on lifestyle modifications alone [15; 66]. A 25% reduction in daytime sleepiness was reported by the participants. Daytime sleepiness is associated with cognitive decline in older adults [67] and may be an early indicator of cognitive decline [68]; therefore, a reduction in daytime sleepiness may indicate a decreased risk of developing MCI [67]. Alongside the improvements in depression, QoL, and sleep, the participants reported healthier life habits across all domains of the Life Habits Checklist, such as neurodegenerative prevention, brain health promotion, body rhythm, dietary habits, and body shape and weight promotion. The latter suggests that participants perceived this intervention to promote several aspects of their health. The baseline MMSE-2 scores in this population were consistent with the healthy control data [69]. Therefore, the lack of change in the MMSE-2 score may be due to a ceiling effect, rather than a lack of efficacy of the intervention. This study was limited by the lack of comparison against a placebo group or one not receiving the intervention. The placebo effect, in cognition studies, has been attributed to several phenomena, including the perception of treatment and anticipatory effects [70; 71]. Thus, future studies on the latter are certainly needed. Further, future studies could consider exploring the potential benefits of the PreCODE protocol alone, and NeuroQ supplementation alone to identify their unique effects. The age range of the participants in the current study was between 45 and 97 years, suggesting a heterogenous population based on age, including younger adults who may not have had a high potential to observe improvements. The literature suggests that mild cognitive impairment may develop prior to onset and, therefore, the current study focused on an at-risk population rather than those with cognitive pathologies [72]. Furthermore, 80% of the participants were western European, which may limit the application to other populations.