Question: How does neuroticism affect Alzheimer's risk, given its link to dementia and cognition?

Context:
["RESULTS: Individuals with scores in the top quartile of neuroticism (hazard ratio = 3.1; 95% confidence interval = 1.6-6.0) or the lowest quartile of conscientiousness (hazard ratio = 3.3; 95% confidence interval = 1.4-7.4) had a threefold increased risk of incident AD.", "Five of nine studies found that higher neuroticism was associated with greater dementia risk (pooled hazard ratio [HR] per unit increase on neuroticism score, HR\u00a0= 1.13, 95% confidence interval [CI]\u00a0= 1.08-1.18, z\u00a0= 5.11, p\u00a0<0.001, N\u00a0= 3,285), and two studies showed it increased risk of MCI. ", "CONCLUSIONS: Neuroticism increased risk for dementia, and conscientiousness reduced risk. ", "RESULTS: Fully adjusted multivariate analyses showed that the association between the presence of APOE [Latin Small Letter Open E]-4 allele(s) and both outcomes was evident among individuals with high levels of neuroticism and extraversion but not among persons with low levels of these traits. CONCLUSIONS: Phenotypic personality dimensions, primarily neuroticism and extraversion, moderate the relationship between APOE [Latin Small Letter Open E]-4 genotype and cognitive outcomes among older adults.", " Individuals with higher baseline scores on vulnerability to stress, anxiety, and depression (neuroticism: odds ratio, 2.0; 95% confidence interval, 1.2-3.5), or lower scores on order and competence (conscientiousness: odds ratio, 0.4; 95% confidence interval, 0.2-0.9) were less likely to remain asymptomatic in the presence of AD neuropathology. Neuroticism (r = 0.26), low agreeableness (r = -0.34), and some facets were also significantly associated with advanced stages of neurofibrillary tangles, but the associations between personality traits and risk of clinical dementia were mostly unchanged by controlling for the extent of neurofibrillary tangles and A\u03b2 neuritic plaques.", "Using mixed models adjusted for age, sex, education, race, social network size, depression, chronic conditions, disability, neuroticism, extraversion, cognitive activity, and physical activity, more social activity was associated with less cognitive decline during average follow-up of 5.2 years (SD = 2.7).", "RESULTS: After controlling for age, the Alzheimer disease group presented significantly higher scores than normal control subjects on current neuroticism, and significantly lower scores on current extraversion, openness, and conscientiousness, while no significant difference was observed on agreeableness. ", " In analyses of specific cognitive systems, neuroticism subscales were related to decline in episodic memory, working memory, and perceptual speed, but not in semantic memory or visuospatial ability. No component of neuroticism was related to the neuropathologic lesions most commonly associated with late-life dementia. CONCLUSIONS: Neuroticism's association with late-life dementia mainly reflects vulnerability to stress and anxiety and their correlation with decline in the ability to process and retain new information.", "The finding that AD risk is associated with elevated Neuroticism and lower Conscientiousness can be added to the accumulating literature documenting the pathogenic effects of these two traits. ", "tau was also correlated with the psychometric measures of episodic/semantic memory, working memory, and processing speed, and with the personality traits of neuroticism and conscientiousness.", "The pre-morbid personality domain of Neuroticism constituted an interesting and theoretically plausible, yet uninvestigated, candidate for such an association. ", "RESULTS: Midlife Neuroticism predicted younger age of dementia onset in females but not in males.", "Preliminary research suggests that cognitively impaired MS patients exhibit elevation in Neuroticism, and diminution in Extraversion, Agreeableness, and Conscientiousness, as do patients with Alzheimer's disease. ", "On the basis of both self-report and informant report, there was an increase in neuroticism and a decrease in conscientiousness in persons with very mild DAT relative to healthy individuals without it, and in persons with mild DAT relative to those with very mild DAT. ", "CONCLUSIONS: As subjective cognitive complaints in the AACD group were related to neuroticism and gender rather than to cognitive performance, their inclusion in diagnostic concepts such as AACD should be revaluated. ", "Multiple studies of individuals with Alzheimer disease have substantiated significant levels of informant-rated change in several domains and facets of the Neuroticism-Extraversion-Openness Personality Inventory, including increases in Neuroticism and decreases in Extraversion and Conscientiousness relative to premorbid personality traits. ", "RESULTS: The AD patients showed higher neuroticism

Answer: Neuroticism increases the risk for dementia and Alzheimer's disease, while conscientiousness reduces the risk. Higher neuroticism scores are associated with greater dementia risk and cognitive decline, as well as vulnerability to stress and anxiety. Neuroticism is also linked to advanced stages of neurofibrillary tangles, which are associated with dementia.