A controlled family study of attention-deficit/hyperactivity disorder and Tourette's disorder.
OBJECTIVE
Although attention-deficit/hyperactivity disorder (ADHD) is frequently comorbid with Tourette's disorder (TD), it is unclear whether they have a common genetic etiology. Familial relationships between DSM-IV ADHD and TD are studied in TD+ADHD, TD-only (TD-ADHD), ADHD-only (ADHD-TD), and control groups.


METHODS
Case-control, direct-interview family study of 692 relatives of 75 TD+ADHD, 74 TD-only, 41 ADHD-only, and 49 control probands collected between 1999 and 2004. Age-corrected prevalence rates, odds ratios, and predictors of TD, ADHD, and OCD among relatives are estimated from blinded best-estimate diagnoses using survival Kaplan-Meier and generalized estimating equation regression analyses.


RESULTS
In relatives of the TD-only group, although ADHD exceeded control rates (p=.03), ADHD-TD (p=.51) rates were not increased. In the ADHD-only group, TD was increased (p=.004) but TD-ADHD rates were not increased (p=.18). Comorbid ADHD+TD diagnoses in relatives were elevated in all case groups (p<or=.03). TD in relatives predicted comorbid ADHD (p<.001), and ADHD in relatives predicted comorbid TD (p<.001). OCD in relatives predicted both ADHD (p=.002) and TD (p<.001) in relatives.


CONCLUSIONS
TD and ADHD are not alternate phenotypes of a single underlying genetic cause. There is an increased risk of comorbid ADHD and TD in affected families, possibly reflecting some overlapping neurobiology or pathophysiology.
Stewart
S Evelyn
SE
Drs. Stewart, Illmann, Geller, and Pauls are with the Psychiatric and Neurodevelopmental Genetics Unit, Massachusetts General Hospital and Harvard Medical School, Boston; Drs. Leckman and King are with the Child Study Center, Yale University School of Medicine, New Haven, CT.
Illmann
Cornelia
C
Drs. Stewart, Illmann, Geller, and Pauls are with the Psychiatric and Neurodevelopmental Genetics Unit, Massachusetts General Hospital and Harvard Medical School, Boston; Drs. Leckman and King are with the Child Study Center, Yale University School of Medicine, New Haven, CT.
Geller
Daniel A
DA
Drs. Stewart, Illmann, Geller, and Pauls are with the Psychiatric and Neurodevelopmental Genetics Unit, Massachusetts General Hospital and Harvard Medical School, Boston; Drs. Leckman and King are with the Child Study Center, Yale University School of Medicine, New Haven, CT.
Leckman
James F
JF
Drs. Stewart, Illmann, Geller, and Pauls are with the Psychiatric and Neurodevelopmental Genetics Unit, Massachusetts General Hospital and Harvard Medical School, Boston; Drs. Leckman and King are with the Child Study Center, Yale University School of Medicine, New Haven, CT.
King
Robert
R
Drs. Stewart, Illmann, Geller, and Pauls are with the Psychiatric and Neurodevelopmental Genetics Unit, Massachusetts General Hospital and Harvard Medical School, Boston; Drs. Leckman and King are with the Child Study Center, Yale University School of Medicine, New Haven, CT.
Pauls
David L
DL
Drs. Stewart, Illmann, Geller, and Pauls are with the Psychiatric and Neurodevelopmental Genetics Unit, Massachusetts General Hospital and Harvard Medical School, Boston; Drs. Leckman and King are with the Child Study Center, Yale University School of Medicine, New Haven, CT.. Electronic address: dpauls@partners.org.
D000293:Adolescent; D001289:Attention Deficit Disorder with Hyperactivity / Q000235:genetics* / Q000503:physiopathology; D016022:Case-Control Studies; D002648:Child; D015897:Comorbidity; D005190:Family; D005260:Female; D006801:Humans; D007406:Interview, Psychological; D008297:Male; D016017:Odds Ratio; D010641:Phenotype; D005879:Tourette Syndrome / Q000235:genetics* / Q000503:physiopathology