Age-related changes in the regulation of behavior by D-1:D-2 dopamine receptor interactions

Functional interactions between D-1 and D-2 dopamine receptor systems appear important in the regulation of psychomotor behavior, and may alter with aging. Male Sprague-Dawley rats of 5 and 20-24 months were challenged with the selective D-2 agonist LY 163502 alone or following pretreatment with the selective D-1 antagonist SCH 23390. Typical sniffing and locomotor responses to LY 163502 alone were significantly reduced in aged animals. Pretreatment with SCH 23390 blocked these typical responses in both young and aged animals, consistent with their regulation by cooperative D-1:D-2 interactions; however, SCH 23390 released a significant excess of atypical limb/body jerking to LY 163502 in aged animals, a response which appears to have its basis in oppositional D-1:D-2 interactions. These results suggest that the net effect of aging on dopaminergic transmission is to reduce tonic activity through D-1 receptors to a greater extent than that occurring through D-2 receptors. As the present aged animals showed a selective loss of striatal D-2 but not of D-1 receptors in radioligand binding studies, such a reduction of D-1-mediated transmission with aging would seem to involve loss of presynaptic function or of postsynaptic mechanisms beyond the D-1 recognition site.

The clinical correlates of neurological soft signs in chronic schizophrenia

Among 16 chronic schizophrenic in-patients, all had at least one neurological soft sign (NSS), and 6 (40%) had definite neurodysfunction. NSS and TD scores were highly intercorrelated, and NSS were significantly correlated with neuroleptic drug exposure. NSS correlated positively with both positive and negative symptoms and cognitive impairment but not with cerebral ventricular size on CT. Patients with neurodysfunction had more positive and negative psychopathology, cognitive impairment and TD than those without. Cerebral ventricular sizes and family histories of schizophrenia were similar in both NSS groups. The presence of NSS may be a simple but important way of identifying a subgroup of schizophrenics with neurodevelopmental predisposing abnormalities, and vulnerability to TD.

Season of birth in schizophrenia. Evidence for confinement of an excess of winter births to patients without a family history of mental disorder

Although it is well recognised that schizophrenic patients are more often born in winter, the significance of this finding remains obscure. Data relating to season of birth and family history were analysed for 561 patients with an ICD-9 diagnosis of schizophrenia. Patients with no family history of any psychiatric disorder group were significantly more likely to be born in winter than patients with a first-degree relative affected by schizophrenia. In comparison with normal population controls, only those without a family history exhibited a significant excess of winter births, suggesting an environmental factor of greater aetiological significance in these patients.

Familial, obstetric, and other clinical correlates of minor physical anomalies in schizophrenia

OBJECTIVE

This study investigated possible antecedents of minor physical anomalies in schizophrenia, particularly in terms of obstetric and genetic factors, and demographic, clinical and cognitive correlates of such anomalies in schizophrenia.

METHOD

Forty-one outpatients satisfying the DSM-III criteria for schizophrenia were examined for minor physical anomalies by using the Waldrop scale. These subjects were drawn from a group of 45 such patients whose cognitive function had been previously evaluated with Trail Making Tests A and B and whose biological mothers had been interviewed for any history of obstetric complications or family history of schizophrenia.

RESULTS

Linear multiple regression analysis showed that higher scores for minor physical anomalies were associated with impaired cognitive flexibility on Trail Making Test B, family history of schizophrenia in a first-degree relative, maternal history of obstetric complications, smaller number of siblings, later position in the birth order, and male sex. A family history of schizophrenia was particularly associated with abnormalities of the mouth. The association between minor physical anomalies in the patients and obstetric complications in their mothers appeared to be confined to instances in which the mother had a history of bleeding in early pregnancy.

CONCLUSIONS

Minor physical anomalies indicate early dysmorphogenesis in schizophrenia, particularly in males, which appears to be associated more reliably with genetic rather than obstetric factors and with cognitive impairment.

Evidence for geographical variations in the prevalence of schizophrenia in rural Ireland

Geographical variations in the rate of occurrence of schizophrenia have been the subject of much speculation and controversy, but it has proved extremely difficult to establish the existence of the phenomenon within a given study area. Using current inpatient and outpatient records and information from key informants active in the community, this study sought to identify all cases of schizophrenia in 36 District Electoral Divisions, constituting a clinical catchment area of 25,178 persons in a rural Irish county. Though the overall prevalence rate (3.3 per 1000) was unremarkable, this obscured a substantial and significant variation in prevalence rates (from 0.0 to 14.3 per 1000) between District Electoral Divisions. Prevalence rates in five District Electoral Divisions made particular contributions to the overall deviation from a statistical model for random occurrences in space. The results indicate spatial inhomogeneity in the prevalence of schizophrenia in rural Ireland and imply geographical variation in environmental or genetic factor(s) of etiologic relevance.

Cognitive dysfunction in schizophrenia followed up over 5 years, and its longitudinal relationship to the emergence of tardive dyskinesia

In this study, 51 chronic schizophrenic in-patients were evaluated for a range of demographic, clinical and medication variables, and followed up over five years. There was no significant overall change in cognitive function in this patient group as a whole, suggesting the absence of active disease at this stage of the illness. The only correlate of individual instances of cognitive deterioration over the study period was the emergence of new cases of tardive buccal-lingual-masticatory but not of limb-truncal dyskinesia, and the greater severity of such movement disorder. A positive family history was also identified prospectively as a predictor of the emergence of tardive dyskinesia in chronic schizophrenia.

Obstetric complications, the putative familial-sporadic distinction, and tardive dyskinesia in schizophrenia

Obstetric complications were more common in the histories of those schizophrenic outpatients without a family history of psychiatric disorder, and were associated with an earlier onset of their illness. Those patients with tardive dyskinesia were more likely to have a family history of psychiatric disorder, less likely to have experienced obstetric complications, and showed greater cognitive deficit. Obstetric complications should be considered in juxtaposition with genetic factors in evaluating the putative familial-sporadic distinction in schizophrenia. Additionally, familial/genetic factors appears to contribute to vulnerability to tardive dyskinesia.

The interaction of clozapine with dopamine D1 versus dopamine D2 receptor-mediated function: behavioural indices

Studies were undertaken to clarify further the mechanism(s) of action of the atypical neuroleptic clozapine, using a behavioural model with the ability to distinguish between relative antagonism of D1 vs. D2 dopamine receptor-mediated function. Pretreatment with low doses of clozapine (2.5-25.0 mg/kg) readily antagonised intense grooming induced by the selective D1 agonist SK&F 77434 (0.75 mg/kg), and in a less consistent manner antagonised hyperactivities induced by the selective D2 agonist LY 163502 (0.05 mg/kg). In animals whose typical responses to SK&F 77434 were antagonised by clozapine, no atypical behaviours such as vacuous chewing emerged. However, in animals whose typical responses to LY 163502 were antagonised by clozapine, a syndrome of atypical limb/body jerking was released. Despite clozapine showing comparable affinities for D1 and D2 receptors in vitro, this behavioural profile shows similarities to that seen when these agonists are given after pretreatment with a selective D1 antagonist, rather than with a selective D2 antagonist or with non-selective neuroleptics. These results suggest that clozapine has some preferential though not selective action in vivo to antagonise D1 dopamine receptor-mediated function.

Sight and insight: regional cerebral metabolic activity in schizophrenia visualised by positron emission tomography, and competing neurodevelopmental perspectives

Over the past several years there has emerged a family of highly sophisticated but technically complex procedures for the visualisation of a range of cerebral functions in living man (Andreasen, 1988). The images they produce are so beguiling not just because of their potential to give new insights into the pathophysiology and treatment of major psychiatric disorders, but because they convey information through a quite fundamental modality: people are only convinced by what they can see. However, initial applications of such new technology have appeared just as likely to generate new questions and contradictions as to provide answers to current issues. This is readily illustrated by recent studies on the imaging of brain dopamine receptors in schizophrenic patients by positron emission tomography (PET) (see Waddington, 1989a).

Obstetric complications in schizophrenia and the validity of maternal recall

The significance of the excess of obstetric complications which appears to characterize the histories of schizophrenic patients is critically dependent on the validity of the source of obstetric information, especially when this is obtained by maternal recall. Twenty-one biological mothers of 17 schizophrenic and four other patients were interviewed for their recollections of individual events characterizing the pregnancy and delivery relating to each patient. These were then compared with those events documented in maternity hospital records. Only in two of the 21 instances (9.5%) were inconsistencies of detail apparent which would have affected the designation of the relevant patient as having, or as not having, experienced major obstetric complication(s). It is concluded that maternal recall can be a surprisingly accurate source of obstetric information in relation to research on schizophrenia.

The lifetime outcome and involuntary movements of schizophrenia never treated with neuroleptic drugs. Four rare cases in Ireland

Four elderly schizophrenic patients who had never been treated with neuroleptics, and a fifth patient who had received only the briefest exposure to such drugs, had retained their distinct clinical characteristics. Involuntary orofacial movements and cognitive dysfunction were found more uniformly than any particular pattern of symptoms.

Spontaneous orofacial movements induced in rodents by very long-term neuroleptic drug administration: phenomenology, pathophysiology and putative relationship to tardive dyskinesia

While understanding of the major clinical and ethical issue of tardive dyskinesia would be greatly facilitated by the development of an isomorphic or homologous animal model, particularly in rodents, this has proved to be a highly contentious issue. The literature on orofacial function in rats administered neuroleptic drugs for substantial proportions of their adult lifespan is reviewed. It reveals the emergence of late-onset orofacial movements in a number of studies, but very early-onset movements or no effect in others. Potential explanations for these discrepancies are considered, and ways of resolving such inconsistencies are suggested. The relationship of these various orofacial phenomena to dopaminergic and non-dopaminergic function, and to clinical syndromes, is critically evaluated.

New putative selective agonists at the D-1 dopamine receptor: behavioural and neurochemical comparison of CY 208-243 with SK&F 101384 and SK&F 103243

Three putative D-1 agonists with nonbenzazepine structures were compared with the prototype benzazepine D-1 partial agonist SK&F 38393 for their behavioural effects in the intact adult rat, and for their relative affinities for D-1 and D-2 dopamine receptors in vitro. SK&F 103243, a restricted conformation analogue of SK&F 38393, and SK&F 101384 (8-Cl-ADTN) showed low affinity for D-1 and D-2 receptors in in vitro binding studies, and failed to induce any behavioural effects on peripheral administration. CY 208-243, an indolophenanthridine derivative, showed appreciable affinity not only for D-1 receptors but also for D-2 receptors, while in behavioural studies it showed some of the characteristics of a partial D-1 dopamine receptor agonist; thus, it failed to promote stereotyped behaviour, but induced episodes of intense grooming which were sensitive to blockade by the D-1 antagonist SCH 23390. No such effect was induced by the selective D-2 agonist RU 24213. CY 208-243 is the first nonbenzazepine which shows some of the properties of a D-1 agonist in the intact adult animal. However, the differences between its in vitro binding characteristics and its functional properties remain enigmatic.

Cognitive impairment, clinical course and treatment history in out-patients with bipolar affective disorder: relationship to tardive dyskinesia

Clinical, neuropsychological and psychopharmacological characteristics were investigated for their ability to distinguish individuals with and without involuntary movements (tardive dyskinesia), among a population of 40 out-patients with bipolar affective disorder and a history of exposure to neuroleptics and lithium. Impaired performance on a test of cognitive flexibility bore the primary association with both the presence and the severity of involuntary movements. The additional relationships identified emphasized further that individual vulnerability to involuntary movements appeared to be associated not with greater duration or dosage of treatment, but with features of the bipolar illness, including number and type of affective episodes, for which that treatment was prescribed.

An evaluation of cranial CT scanning in clinical psychiatry

From 6,300 psychiatric admissions over a 37 month period, all 54 patient referrals for CT were identified and their charts reviewed. CT influenced diagnosis, management or prognosis in 11.7 percent of patients scanned. There was poor correlation between organicity on CT scan and findings on physical examination, laboratory testing, EEG and psychological testing. The mental state examination was the single significant correlate of CT abnormality. We suggest that the use of a formalised mental state examination such as the Mini Mental State, in addition to the usual clinical assessment of mental state, may improve the accuracy of prediction of abnormality on CT scan. The introduction of X-ray computed tomography (CT) is recognised to be one of the most important innovations in the recent history of clinical medicine. In neurology the value of a non-invasive technique for examining the intracranial contents was quickly realised in the areas of diagnosis, particularly in the detection of vascular accidents and tumours. CT has also attained a significant place in psychiatry. In research studies, it has provided important information on schizophrenia, alcoholism and chronic organic reactions. The place of CT in clinical psychiatry is less clear. As its availability has increased, such scans are being requested with increasing frequency in psychiatric patients. Cranial CT is a highly sensitive diagnostic procedure which, when used unselectively, may result in the discovery of incidental findings. Until recently, a function of the psychiatrist in relation to diagnosis was to first seek to distinguish symptoms produced by organic pathology from those produced by functional illness.(ABSTRACT TRUNCATED AT 250 WORDS)

Agonist and antagonist properties of benzazepine and thienopyridine derivatives at the D1 dopamine receptor

Nine structurally related 1-phenyl-1H-3-benzazepine derivatives and two thienopyridines were tested for agonist and antagonist properties at the adenylate cyclase-coupled D1 dopamine receptor in homogenates of the striatum of the rat. The benzazepines SK&F 77434 and SK&F 82958, both of which contain a catechol ring, were agonists; the intrinsic activity of SK&F 77434 was similar to that of SK&F 38393, whereas SK&F 82958 was a full agonist. The remaining benzazepines inhibited the stimulation of adenylate cyclase by dopamine. Antagonist potency depended on the nature of the substituent at position 7 of the benzazepine molecule, 7-halogen compounds being the most potent. The Ki values, obtained from analysis of the antagonism of dopamine-stimulated adenylate cyclase, were significantly correlated with the Ki values for displacement of D1 ligands in binding experiments. Furthermore, antagonist activity of the resolved racemic benzazepine SK&F 83566 resided almost exclusively in the R-enantiomer. The thienopyridine derivatives SK&F 89641 and SK&F 89145 were partial agonists with greater efficacies than SK&F 38393.

Sight and insight: brain dopamine receptor occupancy by neuroleptics visualised in living schizophrenic patients by positron emission tomography

There can be few more impressive sights in contemporary neuroscience and biological psychiatry than the imaging of neurotransmitter receptors in the brains of living human subjects by positron emission tomography (PET; Sedvall et al, 1986). How has such technology advanced our understanding of the pathophysiology and/or treatment of major psychiatric disorders?

The induction of grooming and vacuous chewing by a series of selective D-1 dopamine receptor agonists: two directions of D-1:D-2 interaction

A range of 3- and 6-substituted 1-phenyl-1H-3-benzazepine analogues of SK&F 38393 with D-1 agonist activity were compared for their behavioural effects in the intact adult rat and for their relative affinities for D-1 and D-2 dopamine receptors in vitro. All compounds showed selective affinity for D-1 receptors and induced prominent grooming behaviour, but those with the lower D-1:D-2 selectivity ratios also induced additional episodes of non-stereotyped sniffing, locomotion and rearing. No vacuous chewing was noted. There were marked differences in in vivo potency, extending over a 100-fold range. These responses to the most potent agonist, SK&F 77434 (3N-allyl-SK&F 38393) were reduced enantioselectively by the D-1 antagonist R-SK&F 83566. They were also reduced enantioselectively by the D-2 antagonist R-piquindone, but this pretreatment additionally released a marked vacuous chewing response to SK&F 77434. Prominent grooming may be a characteristic behavioural response to a range of D-1 agonists. It is suggested that there may be at least two forms of functional interaction between D-1 and D-2 systems, manifested concurrently in distinct elements of behaviour: one co-operative, as in the regulation of grooming, and with correlates in the regulation of pallidal neural activity; the other oppositional, as in the regulation of vacuous chewing, and with correlates in the regulation of striatal adenylate cyclase activity.