[Mental retardation as a risk factor to develop a psychotic disease]

One of the main aims of research on schizophrenia has been to pinpoint the early symptoms and signals of the disease before its appearance.

We have examined the diagnoses previously given to patients before they were diagnosed of schizophrenia.

This is a case-control study in which we used a data register including the fields of minimum basic data set (MBDS) whose time period included 1999 to 2005.

In our study, there was a 3.6% frequency of mental retardation and 2.1% one of behavioral and emotional disorders with onset usually occurring in childhood and adolescence, both diagnosed previously. The estimated odds ratio for a mentally retarded patient to suffer adult onset psychosis is 4.6 (95%CI [3.43-6.26]), schizophrenia 5.8 (95% CI [4.20-7.88]), paranoid schizophrenia 4.8 (95% CI [3.39 -6.93]), residual schizophrenia 7.0 (95% CI [4.81 -10.09]) and persistent delusional disorder 2.7 (95% CI [1.57 -4.73]).

It can be concluded from our study that there is an increased frequency of mental retardation among the pathological records of subjects who will be diagnosed with paranoid schizophrenia and residual schizophrenia in the future. This fact supports the etiological thesis of schizophrenia involving neurodevelopment disorders.