Table 1.
Description of Biomarkers Included in this Analysis.
| Biomarker | Brief Defintion | Association With Health |
|---|---|---|
| Neuroendocrine function | ||
| SAM axis activity | ||
| CAT (EPI, NE) | A group of chemically related neurotransmitters released by the adrenal medulla following sympathetic nervous system activation | ↑: ↑ CVD |
| Salivary pH | The level of acidity in the saliva | — |
| sAA | Enzyme secreted by the salivary gland in response to adrenergic activity | — |
| HPA axis activity | ||
| Cortisol | Corticosteroid released by the zona fasciculata of the adrenal cortex | ↑: ↑ CVD; ↓ mental health; ↓ cognitive function |
| DHEA-S | Steroid produced by the zona reticularis of the adrenal cortex | ↓: ↑ CVD; ↓ mental health |
| Endorphin | Neuropeptide primarily produced by the pituitary gland in response to physiological stressors | ↓: ↓ feelings of elation; ↓ stress regulation; ↓ mental health |
| Oxytocin | Neuropeptide produced by the paraventricular nucleus of the hypothalamus and released by the posterior pituitary gland | ↓: ↓ social bonding and attachment; ↓ stress regulation; ↓ mental health |
| Immune function | ||
| Cytokines (e.g., IL, TNF-α) | Proteins produced by various cell types that mainly interact with cells of the immune system | ↑: ↑ age-related diseases (e.g., osteoporosis, atherosclerosis) |
| CRP | Plasma protein produced by the liver in response to inflammation | ↑: ↑ CVD |
| NK cell | A type of lymphocyte critical to the innate immune system | ↓: ↑ cancer; ↑ viral infection; ↑ autoimmune disease |
Note. ↑ = increased; ↓ = decreased; CAT = catecholamine—norepinephrine (NE) and epinephrine (EPI); CRP = C-reactive protein; CVD = cardiovascular disease; DHEA-S = dehydroepiandrosterone sulfate; IL = interleukin; HPA = hypothalamic–pituitary–adrenal; NK = natural killer; sAA = salivary α-amylase; SAM = sympathetic–adrenal–medullary; TNF-α = tumor necrosis factor-α.