Meaning of “correlates” in “.. clinical therapeutic studies of LAC in depression and TRD and its correlates .. ”

Question

From "Myriad of implications of acetyl-l-carnitine deficits in depression":

Nasca et al. (1) were appropriately conservative in interpreting their findings and pointing out multiple directions for future studies. However, a commentator is not bound by such restrictions, and I will note a variety of potential implications that open new avenues for therapeutics and theoretical formulations. Nasca et al. (1) point out the need to further validate their findings and the association with treatment-refractory females with a history of early adversity. Most importantly, well-controlled clinical therapeutic studies of LAC in depression and TRD and its correlates would be an excellent first step. In addition, assessment of LAC levels in patients with bipolar disorder could be of considerable import, especially since childhood adversity is a risk factor for early-onset bipolar disorder and a more difficult and treatment-resistant subsequent course of illness (3).

What is the meaning of "its correlates"? Does it mean "disorders and conditions associated with TRD (treatment-resistant depression)"? Maybe disorders/conditions accompanying TRD?

Answer 1

"Its correlates" refers to "anything that correlates with depression/TRD".

They don't specify what those correlates are (though you could link the statement to the next one talking about bipolar disorder), but it could indeed include related disorders and conditions (such as anxiety disorders and substance abuse). It could also refer to surrogate measures or symptoms rather than particular diagnoses. It's a broadly worded call for further study.