Table 1.
Summary of studies that explored changes in inflammatory and oxidative stress biomarkers, and cognitive measures in individuals with bipolar disorder; BD = Bipolar disorder, HC = Healthy control
| Citation | Subject description (diagnosis, gender (M/F) |
Age (Years) | Design | Duration of illness (years) |
Antipsychotic/mood stabilizer medication (Yes or No) |
Cognitive measures | Inflammatory biomarker |
Statistics | Outcome + Evidence of a link between inflammation and cognition −no evidence of a link between inflammation and cognition |
|---|---|---|---|---|---|---|---|---|---|
| Oxidative stress and cytokines | |||||||||
| Dickerson et al. (2013) Journal of Affective Disorders |
107 BD (31/76) | 36.3±13.4 | Observational study | ≈ 20 years | Yes | Repeatable Battery for the Assessment of Neuropsychological status (RBANS) Wechsler Adult Intelligence Scale (WAIS III), Trail Making Test |
Serum CRP | Logistic regression | +Lower RBANS scores in the High CRP group compared to the Low CRP group |
| Doganavsargil-Baysal et al. (2013) Human Psychopharmacology |
54 euthymic BDI (18/36) 18 HC (5/13) |
BD: 39.46±11.62 HC 38.33±10.80 |
Observational study | ≈ 13 years | Yes | Wisconsin Card Sorting Test (WCST), Rey’s Auditory Verbal Leaning Test (RAVLT) | Serum TNF | Spearman’s correlation, t-test | +BD have higher levels of sTNFr1 and sTNFr2 than HC +BD exhibit lower cognitive performance on WCST and RAVLT than HC +sTNFr2 levels correlate positively with illness duration |
| Neurotrophin | |||||||||
| Aas et al. (2013) Progress in Neuropsychopharmacology |
249 BD (122/127) and 476 HC | BD: 20–40 HC: 34.79±10.25 |
Observational study | Not provided | Yes | California Verbal Learning test, letter number sequencing, digit span forwards/backwards, Color Word Interference test, verbal fluency, block design, matrix reasoning, vocabulary | BDNF gene (not specified whether serum or plasma) | Regression model | +val/met BDNF gene carriers are more vulnerable to childhood trauma sequels, have smaller hippocampal volumes and larger ventricles |
| Barbosa et al. (2012) Journal of Affective Disorders |
25 euthymic BD (8/17) vs 25 HC (11/14) | BD: 50.88±9.11 HC: 48.04±7.08 |
Observational study | 27.88±11.8 | Yes | Mini-Mental State Examination and Frontal Assessment Battery | Plasma BDNF | Mann-Whitney U test, Spearman’s correlation | +Higher BDNF in the BD than HC −No correlation between BDNF and executive functioning |
| Chou et al. (2012) Journal of affective disorders |
23 BD (6/17) and 33 HC (12/21) | HC: 37.6±7.8 BD: 36.5±8.9 |
Observational study | 5.7±4.68 | Yes | Go/No-Go task of the test for attentional performance, Memory (Wechsler Memory scale – III), Word list, Face test, Color trail test, Wisconsin card sorting test | Plasma BDNF | t-test, ANCOVA, correlation | −no difference in BDNF levels between BD and HC +reduced face recognition and accuracy on the WCST in BD compared to HC |
| Dias et al. (2009) Bipolar disorders |
65 euthymic BD (24/41), 50 HC | BD: 37.8±10.51 HC:33.6±9.66 |
Observational study | 13.3±8.78 | Yes | Wechsler Memory Scale, Wechsler Intelligence Scale for adults revised | Serum BDNF | t-test, ANOVA, | −No difference in BDNF levels between BD and HC +Positive correlation between BDNF levels and verbal fluency in BD and HC |
| Rybarkowski et al. (2003) Bipolar disorder |
54 BD I (18/36) | BD: 18–72 (mean 46 years) | Observational study | 16±12 | Yes | Wisconsin Card Sorting Test | Whole blood BDNF gene | t-test | +the val/val BDNF polymorphism exhibits better cognitive functioning than the val/met genotype +the val allele was associated with an earlier onset of illness |
| Rybarkowski et al. (2006) Psychiatry and Clinical Neurosciences |
111 BD (37/74) 160 HC (gender ratio N/A) |
BD: 43.4±13.7 HC: 32.9±11.5 |
Observational study | N/A | N/A | Wisconsin Card Sorting Test, N-back test | Whole blood BDNF gene | t-test, ANOVA | +The percentage of correct reactions to the N-back test and accuracy on WCST was higher in the val/val group compared with val/met and met/met |
| Rybarkowski et al. (2010) International Journal of Neuropsychopharmacology |
60 BD (25/35) 60 HC (25/35) |
BD: 52.6±10.2 HC:52.1±13.6 |
Observational study | 22.2±10.8 | Yes | CANTAB | Plasma BDNF level | Mann-Whitney/Kruskal-Wallis ANOVA | +BD have lower BD have poorer cognitive performance and lower BDNF plasma levels than HC +No difference in plasma BDNF levels between ELR and HC |
| Tramontina et al. (2009) Revista Brasileira de Psiquiatria |
64 BD I (14/50) | BD I: 42.3±11.1 | Observational study | N/A | Yes | Wisconsin Card Sorting Test | BDNF gene (not specified whether serum or plasma) | Mann-Whitney’s U analysis, ANCOVA | −The percentage of non-perseverative errors was higher in the val/val group −No association between met allele and cognitive functioning |