In “Sarek” from TNG melding with Picard resolves Sarek’s emotional control.
In this case, at least, it was less a cure, and more temporarily offloading it to someone else to deal with. Basically the equivalent of Lwaxana affecting the entire Enterprise when she was going through The Phase, or someone with an injured leg leaning on another person to use as a crutch. Except that Sarek was relying on Picard’s emotional processing capabilities.
Presumably his symptoms would return when he ended the psychic connection.