TABLE 2.

Overview of reported FS‐based hippocampal subfield studies, 01/2013‐12/2019. Studies from the first category (heritability studies) are summarized in Section 4.2. The clinical/behavioral/biomarker field was categorized into 15 domains, and the genetic field into 4 domains. Minimum keywords are given for single studies or groups of studies to characterize subdomains

Domain	Studies
Heritability
Heritability	Heritability (Greenspan, Arakelian, & van Erp, 2016; van der Meer et al., 2018; Whelan et al., 2016), heritability and genetic correlation (Elman et al., 2019)
Clinical diagnoses, behavioral and cognitive phenotypes, or other biomarkers
Neurodevelopmental studies	Cognitive aspects during early childhood until early adulthood (Krogsrud et al., 2014; Riggins et al., 2018; Tamnes et al., 2014)
Healthy aging	Cognitive performance (Aslaksen, Bystad, Ørbo, & Vangberg, 2018; Delazer et al., 2019; Engvig et al., 2012; Ezzati, Katz, Lipton, Lipton, & Verghese, 2015; Foster, Kennedy, Hoagey, & Rodrigue, 2019; Pereira et al., 2014; Zammit et al., 2017; Zheng, Cui, et al., 2018; Zheng, Liu, et al., 2018), hormonal influences (Pintzka & Håberg, 2015), protective effects of education (Jiang, Cao, et al., 2019) Other intermediate aging phenotypes: Beta‐amyloid and tau pathology (Caldwell et al., 2018; Hsu et al., 2015; Lindberg et al., 2017; Parker, Cash, et al., 2019; Parker, Slattery, et al., 2019; Rahayel et al., 2019) Memory functions in homeless and marginally housed persons (Gicas et al., 2019) Recollection processes in older age (Hartopp et al., 2018) Subfields as ROI for fMRI (memory formation) (Thavabalasingam, O'Neil, Tay, Nestor, & Lee, 2019)
Pathological aging	Amnestic or vascular MCI, established AD or LBD (de Flores et al., 2015; Evans et al., 2018; Gomar et al., 2017; Györfi et al., 2017; Hirjak, Wolf, et al., 2017; Hirjak, Sambataro, et al., 2019; Kälin et al., 2017; Kang, Lim, Joo, Lee, & Lee, 2018; Khan et al., 2015; Li et al., 2016; Li, Dong, Xie, & Zhang, 2013; Liang et al., 2018; Lim et al., 2012; Lim et al., 2013; Mak et al., 2016; Mak et al., 2017; Parker, Slattery, et al., 2019; Sarica et al., 2018; Shim et al., 2017; Wang, Yu, et al., 2018) Vitamin D in MCI (Al‐Amin et al., 2019), IL‐4 levels in MCI and AD (Boccardi et al., 2019) Spectral analyses (including healthy elderly, subjective memory complaints, MCI and AD; risk of conversion from MCI to AD) (DeVivo et al., 2019; Grajski & Bressler, 2019; Izzo, Andreassen, Westlye, & van der Meer, 2019; Marizzoni et al., 2019; Zhao et al., 2019)
Other neurodegenerative conditions	PD (including dementia) (Foo et al., 2017; Lenka et al., 2018; Low, Foo, Yong, Tan, & Kandiah, 2019; Park et al., 2019; Pereira et al., 2013; Stav et al., 2016; Uribe et al., 2018) Frontotemporal dementia (Bocchetta et al., 2018), LBD, and beta amyloid (Mak et al., 2019) Multisystem atrophy and PD (Wang, Zhang, Yang, Luo, & Fan, 2019) Amyotrophic lateral sclerosis (Christidi et al., 2019), primary lateral sclerosis (Finegan et al., 2019)
Epilepsy	Mesial temporal lobe epilepsy (Costa et al., 2019; Donos et al., 2018; Duarte et al., 2018; Kim, Suh, & Kim, 2015; Kreilkamp, Weber, Elkommos, Richardson, & Keller, 2018; Lee, Seo, & Park, 2019; Long, Feng, Liao, Zhou, & Urbin, 2018; Peixoto‐Santos et al., 2018; Schoene‐Bake et al., 2014; Sone et al., 2016) Subfields as ROI for fiber tracking (Rutland et al., 2018)
CNS (autoimmune) inflammatory disorder	Multiple sclerosis (González Torre et al., 2017; Zuppichini & Sandry, 2018), clinically isolated syndrome (Cacciaguerra et al., 2019), neuromyelitis optica spectrum disorder (Chen et al., 2019), anti‐LGI1 encephalitis (Finke et al., 2017), anti‐NMDA receptor encephalitis (Finke et al., 2016), subtypes of limbic encephalitis (Ernst et al., 2019)
Neurotoxicity	Toxic agents, radiotherapy or hypoxia (Decker et al., 2017; Lv et al., 2018; Ørbo, Vangberg, Tande, Anke, & Aslaksen, 2018; Phillips et al., 2020; Stamenova et al., 2018), alcoholism (Lee et al., 2016; Mole, Mak, Chien, & Voon, 2016; Zahr, Pohl, Saranathan, Sullivan, & Pfefferbaum, 2019), alcohol withdrawal (Kühn et al., 2014), familial risk for alcohol use disorder (adolescents) (Maksimovskiy et al., 2019), cannabis use (Beale et al., 2018), cigarette smoking (Durazzo, Meyerhoff, & Nixon, 2013), preterm birth in school‐aged children (Aanes et al., 2019)
Stress response	Plasma markers of oxidative stress (van Velzen et al., 2017), peripheral inflammatory markers in HIV (Fleischman et al., 2018) expression of glucocorticoid inducible genes in MDD (Frodl, Carballedo, et al., 2014) Socioeconomic status and chronic physiological stress (hair cortisol) (Merz et al., 2019). Perceived stress (Zimmerman et al., 2016)
MDD	Female MDD patients (Han, Won, Sim, & Tae, 2016; Kühn et al., 2012), ECT and treatment response to ECT (Cao et al., 2018; Gryglewski et al., 2019) or antidepressants (Hu et al., 2019; Maller et al., 2017) Acute and remitted depression (Kraus et al., 2019), depression symptom severity (Brown et al., 2019) Neurovascular disease in late onset MDD (Choi et al., 2017), MDD and aging (Szymkowicz et al., 2017), MDD and interleukin‐6 (Kakeda et al., 2018), MDD and other inflammatory markers (Lindqvist et al., 2014), MDD and tryptophan (Doolin et al., 2018) Subfields as ROI for fiber tracking (Rutland et al., 2019)
Bipolar disease	Bipolar disease (Elvsåshagen et al., 2013, 2016), comparison with MDD in adults (Cao et al., 2017; Han et al., 2019) and in children and adolescents (Tannous et al., 2018), lithium effects (Giakoumatos et al., 2015; Hartberg et al., 2015; Simonetti et al., 2016) Predominant polarity (Janiri, Simonetti, et al., 2019)
Schizophrenia	Schizophrenia (Zheng et al., 2019), first episode and chronic disease (Kawano et al., 2015; McHugo et al., 2018), symptom correlates (Han et al., 2016; Kühn et al., 2012), first episode psychosis (Baglivo et al., 2018; Buchy et al., 2016; Li et al., 2018), response to electroconvulsive therapy (Jiang, Xu, et al., 2019), conversion of high risk patients (Provenzano et al., 2020), young relatives at risk (Francis et al., 2013; Ho, Iglesias, et al., 2017; Ho, Holt, et al., 2017), progression patterns (Ho, Holt, et al., 2017; Ho, Iglesias, et al., 2017), genetic and cognitive correlates of schizophrenia (Nakahara et al., 2019) Metacognition and insight deficits (Alkan, Davies, Greenwood, & Evans, 2019; Hýža, Kuhn, Češková, Ustohal, & Kašpárek, 2016; Orfei et al., 2017)
PTSD and early life adversity	PTSD (Averill et al., 2017; Bøen et al., 2014; Hayes et al., 2017; L. Chen et al., 2016), childhood maltreatment (Chalavi et al., 2015; Teicher, Anderson, & Polcari, 2012), verbal abuse (Lee et al., 2018), childhood trauma in schizophrenia and healthy controls (du Plessis et al., 2019), in bipolar disorders and healthy controls (Janiri, Sani, et al., 2019) and in adolescence (Malhi et al., 2019)
Other neuropsychiatric conditions	Pain symptoms (Ezzati et al., 2014), ADHD (Al‐Amin, Zinchenko, & Geyer, 2018), anorexia nervosa (Myrvang et al., 2018), obsessive compulsive disorder (Zhang et al., 2019), and transient global amnesia (Wang, Zhang, et al., 2018), essential tremor (Prasad et al., 2019), rapid eye movement sleep behavior disorder (Campabadal et al., 2019), trigeminal neuralgia (Vaculik, Noorani, Hung, & Hodaie, 2019) Thalamic infarction (Chen et al., 2016), sequelae of microsurgical aneurysm clipping (Hedderich et al., 2019)
Systemic disease	Prediabetes (Dong et al., 2019) primary biliary cholangitis (Mosher et al., 2018), systemic lupus erythematosus (Bódi et al., 2017)
Transdiagnostic approach	Psychosis spectrum (Francis et al., 2013; Haukvik et al., 2015; Mathew et al., 2014; Vargas et al., 2017), unipolar–bipolar spectrum in adults (Cao et al., 2017; Han et al., 2019) or children and adolescents (Tannous et al., 2018) Bipolar disease and schizophrenia (pooling different subfield methods) (Haukvik, Tamnes, Söderman, & Agartz, 2018) Social anxiety disorder, childhood trauma and PTSD (Ahmed‐Leitao et al., 2019)
Genetic or epigenetic candidate analyses and exploratory imaging genetics analyses
Candidate SNPs/genes	BDNF val66met variants (Aas et al., 2014; Frodl, Skokauskas, et al., 2014), TESC gene and MDD (Han et al., 2017), COMT and first‐episode MDD (Otsuka et al., 2019), oxytocin receptor gene and MDD (Na et al., 2018), 22q11.2 deletion syndrome (Mancini et al., 2019)
Epigenetics and gene–environment effects	Epigenetic modifications of glucocorticoid receptor in MDD and controls (Na et al., 2014), environmental adversity and COMT, BDNF, and 5‐HTTLPR (Rabl et al., 2014)
Polygenic risk	Aerobic exercise and polygenic risk for schizophrenia (Papiol et al., 2017; Papiol et al., 2019)
GWAS	GWAS of all subfields (van der Meer et al., 2018), GWAS of the dentate gyrus (Nakahara et al., 2019), GWAS with a methodological focus (Couvy‐Duchesne et al., 2019)

Abbreviations: AD, Alzheimer's disease; ECT, electroconvulsive therapy; FS, FreeSurfer; GWAS, Genome wide association analysis; LBD, Lewy body dementia; MCI, mild cognitive impairment; MDD, major depressive disorder; PD, Parkinson's disease; PTSD, posttraumatic stress disorder; ROI, region of interest.