Sometimes, but not always. In chemistry, catalysts can help initiate or facilitate chemical reactions, but there is often another input required to kick start the process (e.g. heat).

We know that cannabis can act as a catalyst for schizophrenia, but we also know that not everyone who is predisposed to schizophrenia develops it 100% of the time after cannabis use. There are degrees of predisposition, and a bunch of other factors that contribute to this.