Did you know that depressed parents are more likely to have babies with colic? Even fathers who are depressed? I'm pleased that a study finally looks at some other adult than the baby's mother. But this particular study has insurmountable problems, despite the fact that they managed to rule out causality from a crying baby to a depressed parent:
A new study of roughly 7,600 babies and their parents examined the link between parents' depression and babies' colic.
Percentage of babies with colic
• Among non-depressed fathers: 2.2%
• Among fathers with depression: 4.1%
• Among non-depressed mothers: 2.2%
• Among mothers with depression: 4.8%
Here's the insurmountable problem: The parents were asked to recall how often the baby cried. The researchers now think that a diary method would have been more reliable than just trusting on memory, but that wouldn't solve the real difficulty: Depressed people see and interpret the world and all events in a darker and more negative light than people who are not depressed. That's partly how depression is diagnosed.
The diary method wouldn't have helped with this, because it's likely that a baby crying a certain amount would elicit a different diary response from a depressed parent than from one who is not clinically depressed. The only way of getting around this problem would have been medical diagnostic methods for defining a colicky baby, not self-reporting by the parents.