Related by context. Frequent words. (Click for all words.) 60 cognitive function 55 cognitive 55 stamina 55 alertness 54 cognition 50 bone density 50 reflexes 50 eyesight 50 mental 46 endurance 46 dexterity 44 abilities 44 intellect 44 physical 43 physique 43 IQ 43 irritability 42 physiological 42 libido 42 willpower 42 gait 42 comprehension 41 self esteem 41 cognitive decline 41 mental toughness 41 kidney function 41 exertion 41 cognitive impairment 40 sharpness 40 metabolism 40 brainpower 40 brain 40 Cognitive 40 lung function 39 blood sugar 39 muscles 39 agility 39 sleep deprived 39 forgetfulness 39 diet 39 neurological 39 metabolic 38 cerebral 38 longevity 38 superhuman 38 fitness 38 mood swings 38 fluency 38 synapses 37 facial expression 37 toughness 37 blood glucose levels 37 crossword puzzles 37 posture 37 calorie intake 37 dementia 37 poise 37 tai chi 37 facial expressions 37 caffeine 37 nutritional 37 composure 36 arousal 36 slurred speech 36 brains 36 temperament 36 brain scans 36 skill 36 muscular 35 aptitude 35 hydration 35 elasticity 35 antioxidant 35 spry 35 drowsiness 35 smoothness 35 demeanor 35 muscle 35 calmness 35 mastery 35 mentally 35 competence 35 psychological 35 senses 35 tiredness 35 athleticism 35 vitality 35 sedentary 34 aerobic 34 potency 34 skills 34 footwork 34 explosiveness 34 irritable 34 academic achievement 34 sleep deprivation 34 innate 34 Caffeine 34 Mental 34 Alzheimer disease 34 dopamine