Table 2.
Example Scalable Environmental Effect Candidates for Attention-Deficit/Hyperactivity Disorder (ADHD)
| Candidate (citation) | Measurement Qualities | Association | Incidence | ||
|---|---|---|---|---|---|
| Method | Reliability | Human | Animal | ||
| Prenatal: Cigarette19,35,36 | cotinine/report | high/low | 2 | 2 | 15% |
| Prenatal: Alcohol19,36,37 | report, blood | low/moderate | 3 | 2 | 15% |
| Prenatal: POP19,36 | blood | moderate | 3 | 2 | 50–100% |
| Prenatal: maternal stress35,38,39 | report | low | 2 | 2 | minority |
| Peri: LBW19 | weight | high | 1 | n/a | 10% |
| Peri: PDIC40 | rating | moderate | 3 | n/a | 5–10% |
| Peri: hyoxic ischemia41 | cardiac/MRI | moderate | 4 | n/a | minority |
| Peri: parenchymal lesion42 | ultrasound | moderate | 3 | n/a | minority |
| Post: lead-high (> 10 ug/dL)19 | blood | high | 1 | 2 | 5% |
| Post: lead-low (1–10 ug/dL)43 | blood | high | 1 | 4 | 50–100% |
| Post: manganese19 | blood | high | 2 | 4 | 20% |
| Post: mercury19 | blood | high | 3 | 3 | 10% |
| Post: diet-additives19 | blood | high | 3 | 4 | 50–100% |
| Post: diet-fats19 | report | low | 2 | 2 | 50–100% |
| Post: parenting19 | report/obs | moderate | 2 | n/a | minority |
| Post: family/marital conflict19 | report/obs | moderate | 2 | ? | minority |
| Post: adversity44 | report | low-moderate | 1 | n/a | minority |
| Post: maltreatment36 | report | low-moderate | 2 | n/a | minority |
| Post: TV/video19 | report | low/moderate | 3 | na | 50%–100% |
Note: Hypoxia/ischemia or neonatal encephalopathy that is moderate (but not severe) and that excludes cerebral palsy. Association rating by the authors based on their judgment of: 1=well replicated or somewhat specific association; 2=replicated or experimental finding but non-specific to ADHD; 3=conflicting findings, likely complex associations, 4 =few data/non-convincing association; “stress” includes a wide range of moderate stressors some of which are common and some uncommon. “Incidence” reflects the authors’ estimate of occurrence of the risk factor in the general population of the U.S.A based on the studies cited; in most cases these are quite imprecise estimates. Conclusions in the table are based on reviews of the literature or on selected studies as cited in the table. Adversity = composite psychosocial adversity excluding severe trauma or severe deprivation; fam=family; LBW=low birth weight; obs=observations; PDIC=pregnancy, delivery, and infancy complications; Peri = perinatal events; Post=post-natal events; POP=persistent organic pollutants.