It's a sample of people who were admitted to the hospital for "LSD psychosis" compared to people who were admitted for a first schizoid break. They conclude that there are a lot of similarities.
What you really want to know is: the probability of a schizoid break given you have a predisposition P(break|predisposition), the probability of a break given LSD use P(break|LSD, predisposition), the prevalence of predisposition to schizophrenia P(break), or P(break|human). And maybe P(break|LSD), too, for kicks (probability non-predisposed person gets a schizoid break given taking LSD).
With those pieces you can come to some sort of reasonable conclusion about the risk. The paper tells you very little to nothing about it since the samples don't tell you anything about the population. It's like a mechanic concluding Toyotas all need work because all the ones he sees need work.
It's a sample of people who were admitted to the hospital for "LSD psychosis" compared to people who were admitted for a first schizoid break. They conclude that there are a lot of similarities.
What you really want to know is: the probability of a schizoid break given you have a predisposition P(break|predisposition), the probability of a break given LSD use P(break|LSD, predisposition), the prevalence of predisposition to schizophrenia P(break), or P(break|human). And maybe P(break|LSD), too, for kicks (probability non-predisposed person gets a schizoid break given taking LSD).
With those pieces you can come to some sort of reasonable conclusion about the risk. The paper tells you very little to nothing about it since the samples don't tell you anything about the population. It's like a mechanic concluding Toyotas all need work because all the ones he sees need work.