Is there a term for a measure in which an extremely high or low score is considered bad? I'm writing up the results of a measure of emotional management, and I'm hypothesising that under- or over-management of emotions leads to negative consequences.

I'm looking for a term which expresses that both a very high, or a very low score, on this measure, is suboptimal (unlike, for example, IQ, in which a higher score is always considered superior to a lower one), but I can't think of, or find an appropriate term.

It was suggested to me, by a colleague, to use the term "curvilinear", but I don't think that expresses what I want.
I recommend looking at non-scientific writing describing when too much AND too little of something is not good-- when average/in the middle is best for a certain outcome. This is true in many aspects of life, so you'll find a variety of words that may express what you want to convey about these high-end suboptimal and low-end suboptimal scores. 

English StackExchage wordies may know an existing noun/adjective for exactly what you want. If there isn't a word to express what you mean, you're free to create one. Perhaps pairing the prefix "extra-" in the sense of "outside the optimal range", or the prefix "dys-" in the sense of "unfavorable scores" with word(s) relevant to the measure.