Table 3.
Studies of candidate gene × environment interactions in ADHD
| Environmental Risk / Study |
Candidate Genesa |
ADHD Phenotype |
Genetic Main Effect |
Sig. G × E Interaction |
|---|---|---|---|---|
| Prenatal Smoking | ||||
| Becker et al. (2008)88 | DAT1 | ADHD | No | Yesb |
| Brookes et al. (2006)93 | DAT1 | ADHD | Yes | No |
| Kahn et al. (2003)89 | DAT1 | Inattention symptoms | No | No |
| Kahn et al. (2003)89 | DAT1 | Hyp-Imp symptoms | No | Yes |
| Langley et al. (2008)90 | DAT1, DRD4, 5HTT, DRD5 | ADHD | No | Noc |
| Neuman et al. (2007)91 | DAT1, DRD4 | Combined Type | No | Yes |
| Neuman et al. (2007)91 | DAT1, DRD4 | Inattentive Type | No | No |
| Todd et al. (2007)92 | CHRNA4 | Combined Type | No | Yes |
| Todd et al. (2007)92 | CHRNA4 | Inattentive Type | No | No |
| Prenatal Alcohol | ||||
| Brookes et al. (2006)93 | DAT1 | ADHD | Yes | Yes |
| Kahn et al. (2003)89 | DAT1 | Inattention symptoms | No | No |
| Kahn et al. (2003)89 | DAT1 | Hyp-Imp symptoms | No | Yes |
| Langley et al. (2008)90 | DAT1, DRD4, 5HTT, DRD5 | ADHD | No | No |
| Neuman et al. (2007)91 | DAT1, DRD4 | Combined Type | No | No |
| Neuman et al. (2007)91 | DAT1, DRD4 | Inattentive Type | No | No |
| Low Birth Weight | ||||
| Langley et al. (2008)90 | 5HTT, DRD4, DAT1, DRD5 | ADHD | No | Nod |
| Season of birth | ||||
| Seeger 200487 | DRD4 | ADHD+CD | No | Yes |
| Brookes 200886 | DRD4 | ADHD | No | No |
| Socioeconomic status / environmental adversity | ||||
| Lasky-Su et al. (2007)81 | BDNF | Inattention symptoms | Yes | Noe |
| Lasky-Su et al. (2007)81 | BDNF | Hyp-Imp symptoms | Yes | Yes |
| Laucht et al. (2007)82 | DAT1 | ADHD | No | Yes |
| Nobile et al. (In press)135 | COMT | ADHD | No | Yes |
| Nigg et al. (2007)94 | DAT1, DRD4, ADRA2Af | ADHD | Yes | Yes |
| Retz et al. (2008)84 | 5HTT | ADHD | Yes | Yes |
| Waldman et al. (2007)85 | DRD2 | ADHD | No | Yes |
a
ADRA2A = , BDNF = brain-derived neurotrophic factor, CHRNA4 = Nicotinic acetylcholine receptor α-4 , COMT = catechol-O-methyltransferase, DAT1 = dopamine transporter, DRD2 = dopamine D2 receptor, DRD4 = dopamine D4 receptor, DRD5 = dopamine D5 receptor, 5HTT = serotonin transporter,
b
significant in males only,
c
the G × E interaction was significant for DRD5 and oppositional defiant disorder,
d
the interaction was significant interaction for DAT1 and conduct disorder symptoms and for DRD5 and ODD,
e
marginally significant,
f
combined genetic risk.