Different Subtypes Of Schizophrenia Research Articles

The Role of Gender in Identifying Subtypes of Schizophrenia: A Latent Class Analytic Approach

Past literature suggests that schizophrenic men and women may be at different risks for developing different subtypes of schizophrenia. This hypothesis was tested using data from the well-known retrospective cohort family studies, the Iowa 500 and the Iowa non-500. The sample consisted of 171 male and 161 female DSM-III schizophrenic patients and 713 of their first-degree relatives. First, bivariate tests for gender differences were conducted regarding family morbidity, age of onset, premorbid history, season of birth, and expression of deficit and affective symptoms. Restricted maximum likelihood latent class analysis was then used to test whether there was a subgroup of schizophrenic men who were more likely to have a low familial risk for schizophrenia or schizophrenia spectrum disorders, deficit symptoms, poor premorbid history, and birth in the winter months, suggesting possible early environmental insults, compared to schizophrenic women. Results showed that although men were more likely to meet these criteria, women also met them, thus suggesting gender differences in the prevalence of the subtype. Schizophrenic women were more likely to express a form of the illness characterized by dysphoria, persecutory delusions, and a higher family morbidity risk for schizophrenia than schizophrenic men. Results for spectrum disorders among relatives were equivocal with regard to gender.

Differences between paranoid and nonparanoid schizophrenic patients on the somatosensory P300 event-related potential.

Event-related potentials were recorded from schizophrenic patients (n = 30) and healthy controls (n = 30) using a somatosensory-reaction-time version of the oddball paradigm, by stimulating the right and the left median nerve. Latency, amplitude, duration and area of the P300 were measured. The patient group was subdivided into a paranoid (n = 16) and a nonparanoid (n = 14) subgroup and each was compared to controls. After stimulation of the right median nerve the nonparanoid group had a significantly prolonged P300 latency and a normal amplitude. The paranoid subgroup had a trend toward reduction of the P300 amplitude; its P300 latency was normal. After stimulation of the left median nerve, a prolongation of the P300 latency was observed in the paranoid subgroup. This subgroup had also a reduced P300 amplitude, while the nonparanoid patients had both values comparable to those of the controls. Duration and area were not significantly different between the two subgroups of patients and controls. Paranoid and nonparanoid patients showed a different behavior on reaction time parameters. No relationship was observed between P300 parameters and clinical ratings, neuroleptic dose and demographic data. The P300 parameters did not correlate with the reaction time measures. These results are discussed in terms of a disturbance of CNS inhibitory mechanisms in cognitive processes of paranoid schizophrenic patients and could be a further indication that different subtypes of schizophrenia may have different biological substrates.

Contributions of clinical neuropsychology to the study of schizophrenia.

Clinical neuropsychological findings are examined with respect to competing hypotheses about localized neuropathology in schizophrenia. Two general models of structural and functional impairment are described. The first addresses deficits in cortical/subcortical processes concerned with arousal, attention, and higher cortical functions. The second addresses impairments in the balance of lateralized functions consistent with left hemisphere overactivation. Empirical data provide support for both models, and suggest that the explanatory power of these models may vary when they are applied to different subtypes of schizophrenia.

Long-term prognosis and course of schizo-affective, schizophreniform, and cycloid psychoses.

From the Bonn study including 502 patients followed up an average 22.4 years after onset of schizophrenic disease diagnosed according to the criteria of K. Schneider, we selected 113 cases of schizo-affective, schizophreniform, and cycloid psychoses in accordance to the definitions given by Kasanin, Retterstøl, Angst, and Leonhard. These psychoses have a better prognosis than the whole sample: characteristic residues are seen more rarely, complete remissions and noncharacteristic residues more frequently. This group of psychoses differs from the whole sample in the hereditary taint, too: the morbidity risk with affective psychoses and with schizophrenic psychoses in first- and second-degree relatives is higher than in the total sample of the Bonn study. In spite of the better prognosis and other differences described in the paper, we believe that these results do not justify the classification of schizo-affective and related disorders as an independent disease group. Between these different subtypes of schizophrenia only a differential typology and not a differential diagnostic is possible.