A Country Doctor Writes:

I was taught, back in the Stone Age (late 1970’s), that clonazepam, introduced in 1975, had distinct antidepressant properties, besides being just another benzo. I had a patient who reported not feeling well on one particular generic version of it, but doing great on another, who was switched to an equipotent lorazepam and became very depressed. I checked what the literature is showing now and here it is, a little more recent: 2009, 30 years after medical school and 25 years after residency:

Abstract:

Clonazepam, first used for seizure disorders, is now increasingly used to treat affective disorders. We summarize the use of clonazepam to improve the management of depression. Clonazepam is useful for treatment-resistant and/or protracted depression, as well as for acceleration of response to conventional antidepressants. Clonazepam is at this time recommended for use in combination with SSRIs (fluoxetine, fluvoxamine, sertraline) as an antidepressant, and should be used at a dosage of 2.5-6.0 mg/day. If clonazepam is effective, a response should be observed within 2-4 weeks. It is significantly more effective for unipolar than for bipolar depression. Low-dose, long-term treatment with clonazepam exhibits a prophylactic effect against recurrence of depression. Although the mechanism of action of clonazepam has not yet been established, some investigators have been suggested that it involves enhancement of anti-anxiety effects, anticonvulsant effects on subclinical epilepsy, increase in 5-HT/monoamine synthesis or decrease in 5-HT receptor sensitivity mediated through the GABA system, and regulate in GABA activity.

https://pubmed.ncbi.nlm.nih.gov/19330803/#:~:text=Although%20the%20mechanism%20of%20action,receptor%20sensitivity%20mediated%20through%20thehttps://pubmed.ncbi.nlm.nih.gov/19330803/#:~:text=Although%20the%20mechanism%20of%20action,receptor%20sensitivity%20mediated%20through%20the