As the parent of a child with ADHD that is medicated, it seems completely plausible that it could cause depression. When my kid has had too high a dosage (or accidentally takes a double dose) she's like a zombie, completely flat affect, and very little motivation. It's like it drains her life away.
Part of the problem is that it's very difficult to get the right dosage for any given day because diet, metabolism, and hormones seem to have a big impact on how effective it is. We've found it's better to go with a lower-dose extended release, and then let her self-medicate with 5mg regular tablets as needed. This works great now because she's a fairly responsible teenager (when medicated), but it was really hard when she was younger.
Part of the problem is that it's very difficult to get the right dosage for any given day because diet, metabolism, and hormones seem to have a big impact on how effective it is. We've found it's better to go with a lower-dose extended release, and then let her self-medicate with 5mg regular tablets as needed. This works great now because she's a fairly responsible teenager (when medicated), but it was really hard when she was younger.