Table 2.
Study | AL # | List of AL biomarkers | Computation of AL | Traits assessed | Trait scale (items) |
---|---|---|---|---|---|
(Christensen et al., 2018) | 14 | CRP, IL-6, TNF-α, % body fat, blood glucose, BMI, HbA1c, HDL, LDL, total cholesterol, triglycerides, waist/hip ratio, DBP, SBP | Sex-specific z scores→Cut-off points for each biomarker based on sex-specific upper quartile→Composite score ranging 0–14 | E, N | EPQ (101 total) |
(Christensen et al., 2019b) | 14 | CRP, IL-6, TNF-α, % body fat, blood glucose, BMI, HbA1c, HDL, LDL, total cholesterol, triglycerides, waist/hip ratio, DBP, SBP | z scores→Cut-off points for each biomarker based on sex-specific upper quartile→Composite score ranging 0–14 | All 5 | NEO-FFI (12/scale) |
(Crook et al., 2018) | 9 | CRP, fibrinogen, albumin, BMI, HbA1c, HDL ratio, triglycerides, DBP, SBP | Log transformed biomarkers with non-normal distributions→Absolute mean z scores→Summed | N | IPIP (10) |
(Gallagher et al., 2021) | 12 | DHEA-s, CRP, fibrinogen, IGF-1, albumin, BMI, HbA1c, HDL, LDL, waist circumference, DBP, SBP | z score→Cut-off points for each biomarker based on sex-specific upper quartile or sex-specific risk or established criteria→Composite score ranging 0–12 | N | FFMt (3) |
(Hawkley et al., 2011) | 9 | Cortisol, epinephrine, norepinephrine, HbA1c, HDL, total cholesterol, waist circumference, DBP, SBP | Computed z scores (sex-specific z scores for some biomarkers)→Average across z scores | E, N, A | Big 5 PI (20/scale) |
(Luo et al., 2022) | 7 | Blood sugar, HDL, total cholesterol, triglycerides, waist/hip ratio, DBP, SBP | Computed z scores→Average across z scores | E, N | EPI (9/scale) |
(Kobrosly, 2012) | 7 | Average diurnal cortisol slope, IGF-1, IL-6, waist/hip ratio, resting heart rate, DBP, SBP | Computed z scores | N | NEO-FFI (74 total) |
(Milad & Bogg, 2020) | 10 | CRP, fibrinogen, IL-6, fasting glucose, HbA1c, HDL, HOMA-IR, triglycerides, waist/hip ratio, pulse | Log transformed some biomarkers→Parceled biomarkers to reflect functioning within inflammation, glucose, and lipid systems | All 5 | Big Five Adjectives (4/scale) |
(Otto et al., 2021) | 4 | BMI, waist/hip ratio, DBP, SBP | Used cut-off values reported by Seeman et al. (1997) AND sample-specific z score cut-off points based on quartiles→Composite score ranging 0–4 | All 5 | NEO-FFI (12/scale) |
(Richards et al., 2023) | 13 | CRP, fibrinogen, BMI, fasting blood glucose, HbA1c, HDL/total cholesterol ratio, triglycerides, waist circumference, DBP, SBP, FEV1, FVC, PEF | Coded biomarkers based on clinical cut-offs or high-risk quartiles (and doctor decision)→Separated by system (cardiovascular, inflammation, metabolic, body fat, lung function)→Composite score ranging 0–5 | All 5 | MIDI (25 total) |
(Stephan et al., 2016) | 8 | CRP, cystatin C, HbA1C, HDL, total cholesterol, waist circumference, DBP, SBP | Log transformed some biomarkers→z scores→Averaged across all z scores | All 5 | MIDI (26 total) |
Note. Biomarkers are listed by order of system and in alphabetical order within the system: neuroendocrine (DHEA-s), hypothalamic-pituitary-adrenal axis functioning (average diurnal cortisol slope/cortisol), sympathetic nervous/adrenomedullary system (epinephrine, norepinephrine), inflammatory (CRP, IGF-1, IL-6, TNF-α), metabolic (BMI, HbA1c, HDL, HOMA-IR, LDL), cardiovascular (DBP, SBP), and lung function (FEV1, FVC, PEF). DHEA-s=dehydroepiandrosterone sulfate; CRP=high sensitivity C-reactive protein; IGF-1=insulin-like growth factor one; IL-6=Interleukin 6; TNF-α=tumor necrosis factor-α; BMI=body mass index; HbA1c=glycated/glycosylated hemoglobin; HDL=high density lipoprotein; HOMA-IR=homeostasis model assessment-estimated insulin resistance; LDL=low density lipoprotein; DBP=diastolic blood pressure; SBP=systolic blood pressure; FEV1=forced expiratory volume in one second; FVC=forced vital capacity; PEF=peak expiratory flow; E=extraversion; N=neuroticism; A=agreeableness; EPQ=Eysenck Personality Questionnaire; NEO-FFI=NEO-Five Factor Inventory; IPIP=International Personality Item Pool; FFMt=Five-Factor Model traits; Big 5 PI=Big Five Personality Inventory; MIDI=Midlife Development Personality Inventory; EPI=Eysenck Personality Inventory.