Yes, an individual can be diagnosed with schizophrenia and PTSD. The co-occurrence of these two disorders is well known. One study showed that an estimated 29% of patients with schizophrenia, in their sample, had PTSD. That is higher than the estimated lifetime prevalence of PTSD, in the general population, which is approximately 6 to 8%.
Having PTSD in young adulthood could contribute to development of schizophrenia. It is common for people with schizophrenia to have trauma histories. Trauma is a risk factor for psychosis. Psychotic symptoms are sometimes traumatizing and may themselves increase the likelihood of PTSD.
The experiences associated with psychosis may be traumatizing. For example, imagine an individual with psychosis who is taken to jail. The experience of being in jail could be traumatizing and therefore contribute to PTSD.
Substance abuse is another risk factor for psychosis. It is common for young adults to experiment with illegal substances. Substance use increases the potential for psychosis which, as previously described, could affect the development of PTSD.
I hope this answers your question. Please write again if you have additional questions.
Dr. Kristina Randle