SIR: Paul H. Lysaker, Ph.D., et al.1 reported interesting findings that are in line with a previous report by the same research group.2 In their study, patients with prominent obsessive-compulsive symptoms (OCS) had higher levels of positive symptoms, emotional discomfort, and greater deficits in executive function than schizophrenia patients without significant OCS,2 which is consistent with literature suggesting that OCS in schizophrenia is associated with a graver clinical picture. In particular, patients with compulsions also had higher levels of negative symptoms than schizophrenia patients without significant compulsions, even when level of obsessions was controlled statistically.2 A recent study, which examined other neurocognitive domains, revealed that the obsessive compulsive (OC) group had more severe impairments in vigilance but demonstrated superior performance on a measure of visual memory.1
Taken together, these findings suggest that links demonstrated in these and other studies3—5 between OCS and clinical and neurocognitive features of schizophrenia have nonlinear and often unpredictable pattern, which raises the question of causality. Schizophrenia patients with concurrent OCS constitute an intriguing subgroup of individuals. The etiology of OC phenomena in schizophrenia remains unclear. There is significant overlap in the proposed functional circuits and dysfunction at the neurotransmitter level in OCD and schizophrenia, which may lead to co-expression of symptoms. The interactions are multiple and complex, especially in regard to the serotonin and dopamine pathways.6
Three main types of interrelation between OCS and psychotic disorder are described: 1) those whose OCS are independent from psychosis; 2) those whose OCS are partially related to their psychosis; and 3) those whose OCS represent a continuum of their psychosis. Clinically and anamnestically, we are able to distinguish three main subgroups of patients: 1) those who met the DSM-IV criteria for OCD before the development of schizophrenic process (so called "OCD-schizophrenia"); 2) those who began to exhibit OC symptoms around the onset (i.e. in prodromal phase) or at any time during the course of schizophrenia (so called "schizoobsessive disorder"); and 3) schizophrenic patients having transient OC symptoms on different stages of their disease, or under specific circumstances (infections, i.e streptococcal; iatrogenic, i.e. under some atypical neuroleptics, etc..7 Existence of these three groups may explain (at least, in part) the diversity in epidemiological data, clinical manifestations and course, neuropsychological correlates, outcomes of various prognoses and treatments.
It was shown, that preexisting OCD, at least in the early stages of schizophrenia, may have a "protective" effect on some psychotic symptoms and may be responsible for a less virulent course of illness and a higher level of functioning.8 On the other hand, schizo-obsessive patients are more disorganized, tended to have a more chronic course and a greater frequency of social and occupational impairment and a poor long-term outcome.1—6 For these groups, different treatment approaches should be applied. In order to demonstrate it, recently we had shown that schizo-obsessive patients need and benefit from neuroleptics as monotherapy.7 In contrast, antipsychotic monotherapy is often inefficient in OCD-schizophrenia patients and sometimes may worsen the OCS, so these patients should be treated concomitantly with specific antiobsessive agents, i.e. serotonin reuptake inhibitors.7
Concerning the appropriate instruments that should be used for assessing OCS in schizophrenia, the utility of Yale-Brown Obsessive Compulsive Scale as an optimal rating scale could be questionable due to possible difficulties to evaluate resistance and interference to repetitive thoughts and/or behavior in this kind of psychotic patients.3—6 Thus, new valid and reliable scale should be designed and psychometrically confirmed in order to assess properly the specific characteristics of OCS in the context of schizophrenia.
The findings and discussion of Lysaker at al.1,2 support our theoretical assumptions and preliminary typological classifications of OC-schizophrenia subtypes. Moreover, their study, suggested heterogeneity of the OC group and described unexpected experimental findings providing additional clinical-neuropsychological evidence to establishing the internal borders within the OC-schizophrenia spectrum category. We agree with the authors, that further research that will adequately monitor OC and psychotic symptoms, cognitive and psychophysiological functioning in a longitudinal design before the issues of causality can be addressed definitively, is warranted.