I read an article several years ago in which the researchers conducted a survey of lithium responders and non-responders. Now I can't locate the reference. I wondered if you may have run across any information in this area. If lithium worked well previously, it is likely to work well again. Conversely, if lithium did not work well, it is unlikely to work for a new episode.
Lithium works better for patients with some elation and grandiosity accompanying their mania.
Conversely, it does not work well for persons whose mania is intermixed with depressive features, e.g., sadness, tearfulness, pessimism. These latter type episodes are also called mixed mania. Almost half of manic episodes are mixed in type, so this constitutes a large group for whom lithium would not be the first-choice drug. Interestingly, most adolescents also have mixed manic episodes, probably contributing to the evidence of relatively poor response to lithium in this age group. The above factors are specific to lithium, but do not appear to be related to the efficacy of divalproex or carbamazepine.