**1. Introduction**

Apolipoprotein E4 (ApoE4) is the most prevalent genetic risk factor for late-onset Alzheimer's disease (AD) [1]. In mice expressing human ApoE4, the cognitive deficits can be measured in terms of impairments in spatial learning and memory [2] and working memory [3]. Apart from cognitive declines, other behavioral effects are associated with AD and preclinical AD, such as increased anxiety [4], motor function disability, and the inability to learn new motor skills [5,6]. Interestingly, the presence of the ε4 allele was also associated with a two-fold increase in the rate of global motor function decline when compared with non-carriers with comparable age, sex, and education [7].

Oxidative stress has been associated with cognitive and motor declines and has been suggested as a major contributor to AD pathology. Oxidative stress has also been involved in vascular cognitive impairment, a risk for dementia [8]. The brains of AD patients are more vulnerable to oxidative stress, as evidenced in animal models and humans [9]. Furthermore, ApoE4 is associated with the aggravation of AD pathophysiology via increased oxidative stress [10]. Therefore, AD symptomology, especially in the presence of the ApoE4 allele, should be responsive to therapies reducing oxidative stress. Vitamin E is an example of such a therapeutic known to reduce oxidative stress and is able to improve cognitive function in AD patients either alone or in combination [11].

Another well-marketed healthy lifestyle modification is exercise. Physical activity has been associated with a reduced risk of AD [12], delayed AD onset [13], and improved AD symptoms [14], as well as improved vascular cognitive impairments [8]. Furthermore, exercise was even more beneficial in ApoE4 carriers than non-carriers [15,16]. Exercise lowered oxidative stress [17] and improved cognition [18], but also reduced anxiety in the elderly [19] and in rats [20]. Furthermore, it improved motor function in a cognitively impaired geriatric population [21,22], and motor training dramatically reduced injurious falls among AD patients [23,24]. Oxidative stress has also been implicated in the development of neuromuscular disorders (NMDs), and exercise in an intensity- and duration-dependent manner can alter NMDs, as reviewed by Siciliano et al. [25].

Both lines of therapy improved behavioral outcomes associated with AD, and seemed to at least partially involve oxidative stress as part of their mechanism of action. Therefore, it can be hypothesized that combining antioxidants with exercise training will lead to an additive beneficial effect, reducing impairments. While some reports have determined that there can be such a positive interaction [26–28], other studies have found a negative relationship, in which the presence of antioxidants negated the beneficial effects of exercise [29]. How such combinations affect behavioral measures have not been fully explored, and the influence of genotype and sex remain to be evaluated.

The goals of the current study were to determine (1) cognitive, motor, and anxiety phenotypes of middle-aged GFAP-ApoE3 and E4 male and female mice; (2) whether antioxidant intake or exercise training leads to functional improvements; (3) whether the combination of antioxidant and exercise yields an additive beneficial effect; (4) the involvement of oxidative stress and inflammation in behavioral outcomes. Our hypothesis was that moderate exercise and antioxidants would lead to additional beneficial effects when compared to each intervention alone, which would be exacerbated in the ApoE4 genotype. The outcomes are important in deciding the need for antioxidant supplementation in exercising individuals, and as a guiding parameter in genotype-based experiments.
