great example of faulty parallelism

I was watching TV while having something to eat and was delighted by the following grammatical error in a drug commercial:*

"Call your doctor if your depression worsens or you have unusual changes in mood, behavior, or thoughts of suicide."

WHY THIS IS FUNNY (in case you're wondering):

When I taught English, I was frequently annoyed by our grammar book's refusal to distinguish between faulty parallelism as a stylistic error and faulty parallelism as a grammatical error. Sometimes faulty parallelism results in ugly prose, and sometimes it results in sheer nonsense; our grammar book hardly acknowledged the difference.

For example, if I say, "I like to eat, to drink, and sleeping," that's a stylistic error because I'd be much better off saying, "I like to eat, to drink, and to sleep," but it doesn't result in nonsense. Essentially it's a list, and what it's saying is that I like (1) to eat, (2) to drink, and (3) sleeping...or—just as 2(x+y+z) = 2x + 2y + 2z—that (1) I like to eat, (2) I like to drink, and (3) I like sleeping. Grammatically functional, just a confusing and unnecessarily awkward way to put it.

However, if I say, "I like to sing, to dance, and I also like to juggle," then what you've got is a claim that I like (1) to sing, (2) to dance, and (3) I also like to juggle...i.e., (1) I like to sing, (2) I like to dance, and (3) I like I also like to juggle. I like I also like to juggle?! No! Come on! That's not just ugly: it's gibberish!

Anyway, the point is that what the ad clearly meant to say is, "Call your doctor if your depression worsens, if you have unusual changes in mood or behavior, or if you have thoughts of suicide"—or, truer to the original, the more awkward-sounding but still perfectly grammatical "Call your doctor if your depression worsens or you have unusual changes in mood or behavior or thoughts of suicide."** Instead, what the ad says (if you pretend the error is not an error and that the sentence says exactly what is intended) is: "Call your doctor if...you have unusual changes in...thoughts of suicide."

Like—"Huh, that thought of suicide I just had was different from my usual thoughts of suicide. Generally I think about death by cop; throwing myself into a lion cage is a whole new bucket of spiders. Better call my doctor."

Oh, grammar! Will you ever stop bringing me joy?

* For Abilify brand aripiprazole, approved by the FDA in 2002 for use in the treatment of schizophrenia and in 2007 for use in the treatment of bipolar disorder and depression. Aripiprazole also reportedly reduces cocaine craving in rats.

** This is exactly the kind of sentence someone who isn't so good at grammar would likely identify as a run-on, but mood and behavior are both objects of the preposition in, and thoughts, like changes, is a direct object of the verb have. If you're suspicious, think of it this way: "Call your doctor if...you have (a) unusual changes in mood or behavior or (b) thoughts of suicide."