TABLE 4.
Quantitative synthesis and evidence grading for meta‐analyses comparing circulating unsaturated fatty acids between participants with and without mental disorders1
| Study, year (ref) | Mental disorders | Outcome | No. of studies (participants, n) | Original effect metrics | Random-effects summary estimate (95% CI) | Random-effects P | I 2, % | Converted as equivalent OR (95% CI) | 95% Prediction interval | Egger's test P | Largest study estimate (95% CI) | Significant studies | Grading | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| O/E | P | |||||||||||||
| Mazahery et al., 2017 (11) | Autism spectrum disorder | Circulating n–3 PUFAs | 5 (564) | SMD | −0.164 (−0.536, 0.209) | 0.389 | 73.0 | 0.744 (0.379, 1.459) | (0.073, 7.573) | 0.24 | 0.51 (0.32, 0.82) | 3/2.19 | 0.66 | Not significant |
| Circulating n–6 PUFAs | 5 (564) | SMD | 0.569 (−0.186, 1.323) | 0.139 | 93.2 | 2.799 (0.715, 10.968) | (0.015, 518.050) | 0.09 | 0.59 (0.37, 0.95) | 3/1.54 | 0.17 | Not significant | ||
| Circulating DHA | 14 (1291) | SMD | −1.607 (−2.482, −0.732) | <10−3 | 97.3 | 0.055 (0.011, 0.266) | (0.000, 43.982) | 0.11 | 0.45 (0.28, 0.72) | 11/6.78 | 0.03 | Weak | ||
| Circulating EPA | 11 (951) | SMD | −0.437 (−0.901, 0.027) | 0.065 | 90.2 | 0.453 (0.196, 1.050) | (0.019, 10.672) | 0.82 | 1.00 (0.62, 1.60) | 3/0.55 | 0.02 | Not significant | ||
| Circulating AA | 13 (1211) | SMD | −0.826 (−1.481, −0.172) | 0.013 | 95.5 | 0.224 (0.068, 0.733) | (0.002, 26.555) | 0.82 | 0.45 (0.28, 0.72) | 8/6.29 | 0.41 | Weak | ||
| The ratio of AA to EPA in blood | 9 (525) | SMD | 0.662 (−0.109, 1.433) | 0.093 | 93.4 | 3.311 (0.820, 13.367) | (0.023, 470.693) | 0.97 | 5.79 (3.18, 10.33) | 5/6.32 | — | Not significant | ||
| The ratio of AA to DHA in blood | 5 (336) | SMD | −0.080 (−2.223, 2.063) | 0.942 | 98.1 | 0.865 (0.018, 41.855) | (<0.001, >1000) | 0.05 | 127.84 (58.70, 278.41) | 4/4.99 | — | Not significant | ||
| McNamara et al., 2016 (12) | Bipolar disorder | Circulating DHA | 6 (265) | SMD | −0.960 (−1.243, −0.676) | <10−6 | 0.0 | 0.176 (0.105, 0.294) | (0.085, 0.364) | 0.87 | 0.17 (0.07, 0.44) | 4/5.22 | — | Weak |
| Circulating EPA | 6 (265) | SMD | −0.455 (−0.882, −0.027) | 0.037 | 56.9 | 0.438 (0.202, 0.951) | (0.045, 4.317) | 0.27 | 0.44 (0.20, 1.22) | 2/1.96 | 1.00 | Weak | ||
| Circulating LA | 4 (199) | SMD | −0.623 (−1.663, 0.418) | 0.241 | 90.3 | 0.324 (0.049, 2.129) | (<0.001, >1000) | 0.28 | 0.52 (0.19, 1.27) | 1/0.94 | 1.00 | Not significant | ||
| Circulating AA | 6 (265) | SMD | −0.186 (−0.844, 0.471) | 0.579 | 80.4 | 0.716 (0.217, 2.361) | (0.013, 40.473) | 0.69 | 0.95 (0.38, 2.43) | 3/0.31 | <0.01 | Not significant | ||
| Zhang et al., 2016 (15) | Alzheimer disease | Circulating DHA (a 1% increment of blood DHA concentrations) | 3 (1828) | RR | 0.785 (0.561, 1.098) | 0.157 | 62.75 | — | (0.020, 31.045) | 0.16 | 0.96 (0.88, 1.04) | 1/0.16 | 0.15 | Not significant |
| Dementia | Circulating DHA (a 1% increment of blood DHA concentrations) | 5 (3099) | RR | 0.939 (0.864, 1.020) | 0.136 | 57.37 | — | (0.744, 1.185) | <0.01 | 0.99 (0.96, 1.03) | 2/0.25 | 0.02 | Not significant | |
| Mild cognitive impairment | Circulating DHA (a 1% increment of blood DHA concentrations) | 2 (2497) | RR | 0.846 (0.465, 1.540) | 0.585 | 85.84 | — | — | — | 1.11 (0.97, 1.26) | 1/0.16 | 0.15 | Not significant | |
| Hawkey et al., 2014 (13)2 | Attention-deficit/hyperactivity disorder | Circulating n–3 PUFAs | 9 (586) | Hedges' g | −0.409 (−0.563, −0.255) | <10−6 | 0.0 | 0.492 (0.367, 0.659) | (0.346, 0.700) | 0.25 | 0.59 (0.41, 1.16) | 2/1.91 | 1.00 | Weak |
| van der Kemp et al., 2012 (14) | Schizophrenia | Circulating DHA | 6 (194) | Cohen's d | −0.871 (−1.290, −0.452) | <10−3 | 68.1 | 0.207 (0.097, 0.441) | (0.019, 2.269) | 0.45 | 0.485 (0.214, 1.103) | 4/1.67 | 0.06 | Weak |
| Circulating AA | 6 (194) | Cohen's d | −0.767 (−1.390, −0.144) | 0.016 | 85.7 | 0.249 (0.081, 0.771) | (0.005, 12.730) | 0.34 | 0.40 (0.17, 0.91) | 4/1.96 | 0.09 | Weak | ||
| Circulating LA | 4 (113) | Cohen's d | −0.042 (−0.327, 0.244) | 0.774 | 0.0 | 0.927 (0.553, 1.554) | (0.298, 2.883) | 0.57 | 0.88 (0.39, 2.02) | 0/0.21 | — | Not significant | ||
| Circulating DPA | 4 (113) | Cohen's d | −0.924 (−1.225, −0.624) | <10−6 | 0.0 | 0.188 (0.109, 0.323) | (0.057, 0.619) | 0.79 | 0.18 (0.08, 0.43) | 3/0.04 | 0.63 | Weak | ||
| Circulating DTA | 3 (78) | Cohen's d | −0.113 (−0.478, 0.252) | 0.544 | 12.8 | 0.815 (0.421, 1.577) | (0.005, 129.249) | 0.32 | 0.51 (0.17, 1.06) | 0/0.27 | — | Not significant | ||
1
All summary estimates were recalculated based on a random-effects model using the method of DerSimonian and Laird. The 95% prediction interval and Egger's test were not evaluated if available studies were <3. For excess of significance, the P value was not evaluated if the observed number of studies was smaller than expected. AA, arachidonic acid; DPA, docosapentaenoic acid; DTA, docosatetraenoic acid; E, expected number of studies with positive finding; LA, linoleic acid; MD, mean difference; O, observed number of studies with positive finding; ref, reference; SMD, standardized mean difference.
2
The direction of comparison was normalized to mental disorder group versus control group.