Psychotherapy for prenatal depression and infant brain volume: an exploratory signal

Design

Observational follow-up of a randomised trial; exploratory infant outcomes

Population

109 infants of women randomised to interpersonal psychotherapy or enhanced usual care

Primary outcome

Infant hippocampal and amygdala volume at 6 weeks

Effect

Right hippocampus smaller with psychotherapy (d 0.62, p 0.002); left hippocampus and amygdala no difference

This follow-up studied 109 infants of women who had taken part in a randomised trial of brief interpersonal psychotherapy for depression in pregnancy, compared with enhanced usual care. The trial itself had already shown that psychotherapy reduced prenatal depressive symptoms. Infant brain outcomes were exploratory.

Infants of mothers randomised to psychotherapy had a smaller right hippocampal volume on MRI at 6 weeks (effect size d 0.62). Left hippocampal and amygdala volumes did not differ. Smaller hippocampal volume was weakly associated with lower negative emotionality at 6 months (r 0.19).

The direction is unexpected and the meaning of a smaller infant hippocampus is unclear; the authors link it to less negative emotionality, but the correlation is weak. With one significant region out of several measured, chance is a real possibility.

Nothing here changes care. Treating prenatal depression is justified by the mother's outcomes alone, and this study neither adds nor subtracts from that case.

• Treat prenatal depression for the mother's sake; that case does not rest on infant brain imaging.
• Interpersonal psychotherapy remains a reasonable first option for mild to moderate prenatal depression.
• Do not tell parents that therapy will change their baby's brain; the finding is exploratory.
• Expect more studies of this kind; judge them by whether infant outcomes were prespecified.

Why it matters

It is an early attempt to measure whether treating a mother's depression shows up in the child's development, a question clinicians will be asked.

Don't overread it

Infant outcomes were exploratory, only one of several brain regions differed, and the clinical meaning of the difference is unknown.

The statistics, in plain English

An effect size d of 0.62 is moderate, but it comes from one region among several tested, which raises the chance of a false positive. A correlation of 0.19 means hippocampal volume explained under 4% of the variation in later infant emotionality.

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