Study | GAD | Control | Inflammatory markers | Nature of sample | Cross-sectional or longitudinal | Time of day of sample | Fasted period before sample | Assay method | Assay sensitivity reported | Inflammatory marker cut-off used | Confounding factors controlled for |
Bankier et al 38 | 15 | 30 | CRP | Blood | Cross-sectional | NR | NR | High sensitivity turbidimetric immunoassay | Yes | CRP >3 mg/L for significance | Age, sex, education, MDD, obesity, smoking history, type II diabetes mellitus, hypertension, hyperlipidaemia, other mental illness. |
Copeland et al 39 | 146 | 5664 | CRP | Whole blood spots | Longitudinal: sampled aged 9–16, 19 and 21 years old | NR | NR | Biotin-streptavidin-based immunofluorometric system | Yes | Excluded if >10 mg/L | Age, sex, race, SES, BMI, medication use, substance use, recent physical illness, chronic illness. |
De Berardis et al 42 | 70 | No control | CRP | Serum | Cross-sectional | 07:00–08:30 | 10-hour fast | Highly sensitive nephelometric assay | Yes | No | Age, sex, BMI, MDD, physical illness, other mental illness, medication use |
Hoge et al 44 | 70 | No control | TNF-α, IL-6 | Plasma | Longitudinal: sampled prepsychological and postpsychological intervention | 13:00–16:30 | NR | NR | No | No | Age, sex, ethnicity, MDD, medication use, physical illness, other mental illness |
Hou et al 47 | 54 | 64 | IL-4, IL-10, TNF-α, IFN-γ | Serum | Cross-sectional | 09:00–10:00 | NR | Multiplex ultrasensitive immunoassay | Yes | No | Age, sex, BMI, smoking, alcohol consumption, MDD, physical illness, other mental illness. |
Khandaker et al 33 | 26 | 3392 | CRP | Serum | Cross-sectional | NR | ‘Overnight’ | Automated particle-enhanced immunoturbidimetric assay | No | Excluded if >10 mg/L | Age, sex, parental SES, ethnicity, maternal age at delivery, concurrent infection, family history of inflammatory disease, MDD. |
Korkeila et al 40 | 116 | CRP, TNF-α, IFN-γ | Blood | Cross-sectional | NR | NR | NR | No | No | BMI. | |
Nayek and Ghosh34 | 50 | 50 | CRP | Serum | Cross-sectional | NR | NR | Particle-enhanced turbidimetric immunoassay technique | No | Excluded if ‘raised ESR’ | Age, sex, SES, religion, marital status, locality, BMI >30, physical illness. |
Ogłodek et al 48 | 120 | 40 | SDF-1, CCL-5, MCP-1 | Plasma | Cross-sectional | 07:00–09:00 | Fasted, duration NR | ELISA | Yes | No | Sex, other mental illness, physical illness, substance misuse, smoking status, medication use. |
Tang et al 35 | 48 | 48 | CRP, IL-1α, IL-2, IL-5, IL-6, IL-8, IL-12p70, IFN-γ, GM-CSF | Serum | Cross-sectional | 09:00–10:00 | NR | ELISA | No | No | Age, sex, education, BMI, smoking status, alcohol consumption, acute physical illness, other mental illness, medication use. |
Tofani et al 46 | 14 | 10 | IL-2, IL-10 | Plasma | Cross-sectional | NR | NR | Immunoenzymatic assay | No | No | Medication use. |
Vogelzangs et al 36 | 454 | 556 | CRP, IL-6, TNF-α | Plasma | Cross-sectional | 08:00–09:00 | ‘Overnight’ | ELISA | Yes | No | Age, sex, education, smoking status, alcohol intake, physical activity, BMI, physical illness, medication use, MDD, other mental illness. |
Yang et al 45 | 28 | 41 | IL-1, IL-4, IL-6, TNF-α | Saliva | Cross-sectional | NR | ‘Overnight’ | ELISA | Yes | No | Age, sex, smoking status, BMI, medication use, physical illness, other mental illness. |
Zahm41 | 93 | 728 | CRP, IL-6, TNF-α | Serum | Cross-sectional | No (fasting, duration NR) | Fasted, duration NR | ELISA | Yes | No | Age, sex, SES, BMI, illicit substance use, alcohol use, smoking status, physical activity, physical illness. |
BMI, body mass index; CCL-5, chemokine C-C motif ligand 5; CRP, C reactive protein; ESR, erythrocyte sedimentation rate; GAD, generalised anxiety disorder; GM-CSF, granulocyte-macrophage colony-stimulating factor; IFN-γ, interferon-γ; IL, interleukin; MCP-1, monocyte chemoattractant protein-1; MDD, major depressive disorder; NR, not reported; SDF-1, stromal derived factor-1; SES, socioeconomic status; TNF-α, tumour necrosis factor-α.