Table 1.
Selective list of biological age indicators.
| Category | Biological age indicator |
Method | Correlation with chronological age |
Evidence for mental health association | Representative survival or method-related references |
|---|---|---|---|---|---|
| Functional & physiological measures |
Walking speed/gait | Timed distance walked Self-report |
Inverse | Impaired in depression (Lemke et al., 2000; Michalak et al.,2009) | (Cooper et al., 2010†; Graham et al., 2008†; Yates et al., 2017) |
| Hand-grip strength | Dynamometer | Inverse | Lower in depression (Lee et al., 2018; Lever-van Milligen et al., 2017) | (Bohannon, 2008†; Ortega et al., 2012; Sasaki et al., 2007; Sayer and Kirkwood, 2015) | |
| Lung function | Spirometer | Inverse | Impaired in depression (Lever-van Milligen et al., 2017) | (Stavem et al., 2005) | |
| Brain measures | Brain ageΔ | T1-MRI | Positive/high | Higher in SCZ (Schnack et al., 2016), MDD, BPD, and psychosis (risk) (Kolenic et al., 2018; Koutsouleris et al.,2014) Inconsistent in BD (Hajek et al., 2017; Nenadic et al., 2017) Higher with more negative fateful life events (Hatton et al.,2018) |
(Cole et al., 2018, 2017) |
| Cellular measures | Respiratory capacity | Mitochondrial enzymatic activities Respiratory capacity in fresh cells |
Inverse | Enzymatic activities: correlated with previous day positive mood (Picard et al., 2018) Cellular respiration: associations with early life adversity (Boeck et al., 2018a) and MDD (Boeck et al., 2018d; Karabatsiakis et al., 2014) |
(Gonzalez-Freire et al., 2018;Greco et al., 2003; Tyrrell et al., 2015) |
| Molecular measures |
Telomere length | qPCR Southern blot Q-FISH |
Inverse | Shorter in MDD (Schutte and Malouff, 2015), anxiety disorders (Malouff and Schutte, 2017), SCZ (Polho et al.,2015), PTSD (Li et al., 2017) N.S. in BD |
(Aubert et al., 2012; Aviv et al.,2011; Cawthon, 2002; Wang et al., 2018†) |
| Epigenetic ageΔ | Microarray and sequencing | Positive/high | Increased in response to traumatic stress (Wolf et al., 2018), life stress (Zannas et al., 2015), BD (Fries et al., 2017), MDD (Han et al., 2018; Whalley et al., 2017) N.S. in SCZ (McKinney et al., 2017a) |
(Chen et al., 2016†; Christiansen et al., 2016; Hannum et al., 2013; Horvath, 2013; Marioni et al., 2015; Vetter et al., 2018) | |
| Transcriptomic ageΔ | RNA-seq | Positive/moderate to high | NA | (Huan et al., 2018; Peters et al., 2015) | |
| Proteomic ageΔ | Mass spectrometry | Positive/high | NA | (Menni et al., 2015; Tanaka et al., 2018) | |
| Metabolomic ageΔ | Mass spectrometry | Positive/high | NA | (Chaleckis et al., 2016; Hertel et al., 2016) | |
| GlycomicsΔ | Microarray and mass spectrometry | Positive/moderate to high | Altered in MDD (Boeck et al., 2018c; Park et al., 2018) GlycoAge Test was higher in PTSD (Moreno-Villanueva et al., 2013) |
(Krištić et al., 2014; Peng et al., 2018; Vanhooren et al., 2008; Yu et al., 2016) | |
| ccf-mtDNA | qPCR | Positive | Higher in plasma of suicidal patients (Lindqvist et al., 2016) and MDD (Lindqvist et al., 2018) Acutely elevated with induced psychological stress in plasma (Hummel et al., 2018) and serum (Trumpff et al., 2019) |
(Pinti et al., 2014) | |
| mtDNAcn | qPCR (whole blood) |
Inverse | Higher in BD (Fries et al., 2017) No evidence for an association with depression Increased in mixed psychiatric disorders |
(Mengel-From et al., 2014; Verhoeven et al., 2018; Zhang et al., 2017) |
Abbreviations: BD, bipolar disorder; BPD, borderline personality disorder; ccf-mtDNA, circulating cell-free mitochondrial DNA; MDD, major depressive disorder; MRI, magnetic resonance imaging; mtDNAcn, mitochondrial DNA copy number; NA, not applicable; N.S., not significant; PTSD, post-traumatic stress disorder; qPCR, quantitative polymerase chain reaction; Q-FISH, quantitative fluorescent in situ hybridization; SCZ, schizophrenia. Note that correlation coefficients (r) for biological age indicators and chronological age is dependent on the age range within each dataset and should not be use as sole metric of accuracy. Criteria used for size of r: High: 0.7-0.9 (−0.7 to −0.9); Moderate: 0.5-0.7 (−0.5 to −0.7); Low: 0.3– 0.5 (−0.3 to −0.5); Negligible: 0 - 0.3 (−0.3 to 0). Effect size reflects correlation coefficient reported in the original publications of the multivariate composites, indicated byΔ. Systematic reviews and meta-analytic studies are indicated by†