Posted by Phillipa on March 29, 2011, at 21:59:10
Finally a study that says children from families with high incidence of anxiety more prone themselves. May be genetic link Phillipa
Medscape Medical News from the:
Anxiety Disorders Association of America (ADAA) 31st Annual ConferenceFrom Medscape Medical News > Psychiatry
Anxiety 'Density' in Families Predicts Disorders in Children
Caroline HelwickAuthors and Disclosures
March 28, 2011 (New Orleans, Louisiana) The number of family members with a specific anxiety disorder is linearly related to the risk that a child within that family will also develop that specific disorder, according to a study of almost 10,000 children in Brazil.
Presented here at the 31st Annual Conference of the Anxiety Disorders Association of America (ADAA) by Giovanni A. Salum, MD, from the Brazilian National Institute for Developmental Psychiatry and Federal University of Rio Grande do Sul, Porto Alegre, Brazil, the High Risk Cohort Study for the Development of Childhood Psychopathology and Resilience evaluates and follows children deemed to be at risk for psychiatric disorders.
In the PREVENTION study, investigators are asking whether there is a "quantitative contribution of family liability," that is, whether a high density of anxious symptoms increases anxiety symptoms in children.
"We found, in our preliminary study, that for families in which no members had an anxiety disorder, the prevalence in the index child was only 10%. This increased to 30%, if 1% to 20% of relatives were affected and to 80% if at least 80% of affected family members were affected," Dr. Salum noted.
"There is a linear dose response with regard to the family load of psychopathologic symptoms," he observed.
Need to Refine Risk Estimates
In the current literature, there is no clear definition of "at risk" children to be used in short-term preventive interventions, Dr. Salum pointed out. Therefore, the study aimed to find predictors associated with normal and abnormal development to refine the concept of risk for future studies.
Biological parents of 9937 children age 6 to 12 years answered the Family History Screen, adjusted to provide information about the biological parents of the index child, biological siblings, and half-siblings. Mental health information was collected on 45,394 family members; at least 1 symptom of anxiety was noted in 3095 (31.1%) children.
Each parental interview took 2 to 4 hours. Four 1-hour sessions were also held with the index child, and anxiety symptoms were evaluated by the same instrument.
Of these, investigators randomly selected 1000 families and culled another 1500 families in which both child and family members had symptoms of psychiatric loading. These families formed the basis of the preliminary results presented at the meeting.
The investigators evaluated the psychiatric "density effect" by constructing a formula they labeled the Family Liability Index (FLI) for anxious and depressive symptoms. The FLI formula was derived by summing the number of family members found on the interview to have at least 1 symptom of anxiety or depression, divided by the number of family members, correcting for relatedness.
"By calculating the FLI, showing the percentage of family members affected, the rate of psychopathology in the whole family can be estimated, he said. "Its a new concept. Most studies just determine whether psychopathology is present or absent in the family but we are advocating for a quantitative role."
For each family, an FLI was classified according to the percentage of affected family members: 0% (comparison level), 1% to 20%, 21% to 40%, 41% to 60%, and 81% to 100%. The finding that in some families 80% of its members are affected by the same anxiety disorder may sound suspicious, Dr. Salum acknowledged, but he pointed out that in a sample of 45,000 persons "you will see some very sick families."
The results of each FLI for each psychiatric or group of psychiatric disorders were plotted against each childs symptoms.
Clear Dose Response
Even after adjustment for confounders in the multiple regression analysis, the FLI showed a dose-response effect for family liability that augmented anxiety symptoms in the children, Dr. Slum reported.
The prevalence ratio between children who were negative and positive for anxiety disorders at each level of FLI class compared to the comparison level were, respectively, 1.8 (95% confidence interval [CI], 1.4 - 2.2), 2.3 (95% CI, 2.1 - 2.6), 3.1 (95% CI, 2.8 - 3.5), 4.1 (95% CI, 3.6 - 4.7), 4.9 (95% CI, 4.5 - 5.6) (P < .001 for all).
Dr. Salum noted that the prevalence ratio is a more conservative figure than an odds ratio. For example, a prevalence ratio of 1.8 is equivalent to an odds ratio of around 3.0. This gives an indication of the increased risk observed as family liability increased.
A high density of specific phobias, panic disorder, or agoraphobia was particularly predictive of the childs risk, he noted.
For specific phobias, risk exceeded 80% in the child for whom 81% to 100% of the family suffered from the same phobia, and dropped only to 70% when 61% to 80% were affected.
Risk "Very High" for Panic Disorders
When panic disorder was observed in 61% to 80% of family members, the risk for the child was nearly 60%; when more than 80% were affected, the risk rose to about 70%, he said.
"The risk was very high for panic disorders," he reiterated. "When you have 40% of family members with this disorder, you have a greater chance of developing panic disorder than not having it."
For agoraphobia, the risk in the child reached 80% in the presence of the highest FLI classification and was 40% when 61% to 80% of family members were agoraphobic. Social anxiety risk was also very high if at least 61% of members were affected.
The dose response was somewhat less for generalized anxiety disorder, with a risk less than 40% even when 100% of family members were affected.
With regard to the risk for any psychiatric disorder (not just anxiety), family liability was less robust but still significant, reaching about 50% at the highest FLI but hovering around 20% with no affected family members.
"For almost all the anxiety disorders, we found a high signal for the specific psychopathology," he said.
Additional components of the study will include a structural and functional neuroimaging protocol in 750 children and serum biomarker analysis in 400 of these children.
Major Contribution to the Literature
Thomas Ollendick, PhD, director of the Child Study Center at the Virginia Polytechnic Institute in Blacksburg, Virginia, commented that the findings add greatly to what is known about family clustering of psychopathology.
"Most of the literature suggests that if the parent has an anxiety disorder, the child has an increased probability as well, but there has not been specificity for this that is having any disorder means the child is at risk for any disorder. This probably means our small study populations have not had the power to look at this more specifically. In a study of 10,000 people, however, you have opportunity to find things you wont find with 300 subjects."
His noted research has yielded similar observations. "In our trials with phobic kids, we find more parents with these same phobias than with other anxiety disorders. It is probably some combination of a genetic influence and modeling. DNA testing, which the investigators will do on a sample, will be informative. The data are exciting."
Dr. Salum and Dr. Ollendick have disclosed no relevant financial relationships.
Anxiety Disorders Association of America (ADAA) 31st Annual Conference. Presented March 25, 2011.
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