August 26, 2014

expert reaction to pregnancy, antidepressants, ADHD and autism

A paper in the journal Molecular Psychiatry has reported an association between prenatal exposure to antidepressants and development of ADHD but not autism.

Dr Celso Arango, Scientific Director of the Spanish Centre for Biomedical Research in Mental Health (CIBERSAM), Madrid, said:

“This is a nice study, however, a more robust piece would be an epidemiological cohort study in which subjects were not chosen specifically because they were depressed. That is the only way to assess causality, where one takes a large group of subjects (e.g. people born in one city during a certain period of time, follow X women from a catchment area before becoming pregnant etc) and then follows them and assesses how a particular variable, in this case the use of antidepressants during pregnancy, increases the risk of a given condition.

“It is not clear how big the effect of antidepressant use is. Certainly it is minimal compared to genetic factors. Genetic variability (heritability) explains around 70% of autism cases.  Environmental factors are more important in ADHD because they change not only the expression of the disorder but, more importantly, the threshold of diagnosis (for example the controversy in the USA where the prevalence of ADHD varies by state because of the laws over school entrance).

“Most antidepressants have the same, or similar, mechanisms of action so I would not expect many differences between different types of antidepressants. However, some drugs do have different mechanisms (e.g. influencing dopamine activity) but this study has not been able to assess that question as the sample is too small.

“From the child’s perspective it is likely that the potential harm caused by any increased risk of ADHD or autism would be much less than the potential harm of having a mother suffering from depression. And of course, that is without even mentioning the issue of depression causing mothers to die by suicide during pregnancy. Researchers are only just beginning to realise that it is not psychiatrists, psychologists or neuroscientists that are having the biggest impact on preventing mental health issues – it is gynaecologists.

“In summary, this research does not mean that women should stop taking their antidepressants. It suggests that we need more animal and human research on how this drug affects the normal neurodevelopment of children and then weigh those impacts against the negative consequences of brains developing in stressed and depressed pregnant mothers.”

Prof Guy Goodwin, President of the European College of Neuropsychopharmacology (ECNP), said:

“Confounding by indication is the bane of all epidemiological studies of drug exposure. This publication recognizes the problem but does not have an adequate solution. The final conclusion, that antidepressant exposure in pregnancy does not cause autism but does cause ADHD, strains credibility because the odds ratios on which this conclusion is based are so similar and any differences depend heavily on the modelling of confounds. Rates of exposure to antidepressants were also quite low, so the power of the study is probably limiting.

“It remains possible, even likely, that the effect observed is due to increased genetic risks of psychiatric disorder in the offspring of the women prescribed antidepressants, rather than the effects of the drugs. This was the conclusion for much more certain diagnoses (of birth defects) in a substantially larger sample in which an analogous question was asked (Jimenez-Solem et al BMJ Open 2012; 2; e001148. doi:10. 1136/bmjopen-2012-001148).”

‘Prenatal antidepressant exposure is associated with risk for attention-deficit hyperactivity disorder but not autism spectrum disorder in a large health system’ by Clements et al. published in Molecular Psychiatry on Tuesday 26^th August. 

All our previous output on this subject can be seen at this weblink: http://www.sciencemediacentre.org/?s=depression%20pregnancy&cat

Declared interests

Guy Goodwin has acted as a consultant to companies who have developed and marketed antidepressants.