Atypical antipsychotic-induced metabolic side effects: insights from receptor-binding profiles

Atypical antipsychotic drugs offer several notable benefits over typical antipsychotics, including greater improvement in negative symptoms, cognitive function, prevention of deterioration, and quality of life, and fewer extrapyramidal symptoms (EPS). However, concerns about EPS have been replaced by concerns about other side effects, such as weight gain, glucose dysregulation and dyslipidemia. These side effects are associated with potential long-term cardiovascular health risks, decreased medication adherence, and may eventually lead to clinical deterioration. Despite a greater understanding of the biochemical effects of these drugs in recent years, the pharmacological mechanisms underlying their various therapeutic properties and related side effects remain unclear. Besides dopamine D(2) receptor antagonism, a characteristic feature of all atypical antipsychotic drugs, these agents also bind to a range of non-dopaminergic targets, including serotonin, glutamate, histamine, alpha-adrenergic and muscarinic receptors. This review examines the potential contribution of different receptors to metabolic side effects associated with atypical antipsychotic treatment for all seven agents currently marketed in the United States (risperidone, olanzapine, quetiapine, ziprasidone, aripiprazole, paliperidone and clozapine) and another agent (bifeprunox) in clinical development at the time of this publication.

Structural abnormalities in the frontal system in schizophrenia. A magnetic resonance imaging study

Thirty-eight schizophrenics and 49 normal controls underwent magnetic resonance imaging. Midline sagittal cuts indicated that the schizophrenics had significantly smaller frontal lobes, as well as smaller cerebrums and craniums. The findings are consistent with some type of early developmental abnormality that might retard brain growth and therefore skull growth. These findings are confirmed on a smaller sample of patients on whom we have coronal cuts. Decreased cerebral and cranial size are associated with prominent negative symptoms, although decreased frontal size is not. Decreased cranial and cerebral size was also associated with impairment on some cognitive tests. These findings are consistent with the hypothesis that some schizophrenics may have a type of early developmental abnormality associated with prominent negative symptoms and cognitive impairment. Further, the results suggest that schizophrenics may have a type of structural frontal system impairment. Thus, they provide anatomic evidence for the "hypofrontality hypothesis."

A controlled magnetic resonance imaging study of corpus callosum thickness in schizophrenia

Two previous postmortem studies reported an increased thickness of the corpus callosum in schizophrenic patients compared to psychiatric controls. We report an in vivo study of the corpus callosum in schizophrenic patients (n = 38) and healthy controls (n = 41) using magnetic resonance (MR) brain imaging. A significant increase in mean callosal thickness was found in the middle and anterior, but not the posterior, parts of the callosal body. However, when the patients and controls were compared by gender and handedness, schizophrenic men were found not to differ from control men in callosal thickness, regardless of handedness, whereas schizophrenic women were found to have a highly significant increase in callosal middle and anterior thickness compared to control women. The data suggest that increased callosal thickness in schizophrenia is gender related, a factor that is not considered by postmortem studies. The implications of increased callosal dimensions in female schizophrenics are discussed.

A review of the effect of atypical antipsychotics on weight

Controlled research trials have shown that atypical antipsychotics have important advantages over standard antipsychotics, including a broader spectrum of efficacy and improved tolerability profile, particularly with regard to neurological adverse events such as extrapyramidal symptoms (EPS). Some atypical antipsychotics, however, tend to cause significant weight gain, which may lead to poor compliance and other adverse health effects. The mechanisms involved in antipsychotic drug-related weight gain are as yet uncertain, although serotoninergic, histaminic, and adrenergic affinities have been implicated along with other metabolic mechanisms. The atypical antipsychotics vary in their propensity to cause weight change with long-term treatment. Follow-up studies show that the largest weight gains are associated with clozapine and olanzapine, and the smallest with quetiapine and ziprasidone. Risperidone is associated with modest weight changes that are not dose related. Given the equivalent efficacy of atypical antipsychotics, weight-gain profile is a legitimate factor to consider when constructing an algorithm for treatment due to the serious medical consequences of obesity.

Cognitive impairment and cerebral structure by MRI in bipolar disorder

The distinction between bipolar disorder and schizophrenia customarily follows examination of the clinical symptomatology and course of illness. The presence of cognitive impairment has been held to be uncommon in bipolar disorder and more likely in schizophrenia. This study explored neuropsychological function in 30 ambulatory outpatients with a DSM-III-R diagnosis of bipolar affective disorder (all of whom had been psychotic during manic episodes), comparing their performance with that of controls. These bipolar patients proved to have significant levels of diffusely represented cognitive impairment when compared with controls. Further, the degree of impairment was significantly correlated with reduction in midsagittal areas of brain structures measured on magnetic resonance imaging scans. The implications of these findings in relation to bipolar disorder are discussed.

Neuropsychological correlates of negative, disorganized and psychotic symptoms in schizophrenia

Recent studies suggest that three dimensions (negative, disorganized and psychotic) categorize schizophrenic symptoms. A developing literature indicates distinct cerebral correlates of each symptom cluster, but few investigations have determined their neuropsychological correlates. In the present study, the Schedules of Negative and Positive Symptoms measured symptom severity in 62 schizophrenics, and a subsequent principal components analysis revealed three symptom dimensions. Factor scores, age and parental socio-economic status were simultaneously entered into regression equations to explain variance across a broad neuropsychological test battery. Negative symptoms were associated with deficits involving intelligence, executive function, memory, sustained-attention and sensory-motor function, whereas disorganized symptoms correlated with decreased intelligence, attention-span and sensory-motor function. Psychotic symptoms were unrelated to deficits. These data are consistent with hypotheses that these three symptom dimensions have distinct neurobehavioral correlates.

Cerebral ventricular enlargement in schizophrenia. A preliminary follow-up study

Lateral cerebral ventricular enlargement is now known to occur in some schizophrenic patients. To determine whether ventriculomegaly in schizophrenia is a static vs progressive process, we conducted a follow-up computed tomographic brain scan study on 11 young male patients, three years after initial scans were obtained. No significant change was found in the mean ventricles-brain ratio of this small schizophrenic sample after three years. Four of 11 patients showed noticeable increases (greater than 50%) in individual ratio. Methodologic problems are discussed and the need for follow-up studies as a research strategy is emphasized.

The case for long-acting antipsychotic agents in the post-CATIE era

OBJECTIVE

Long-acting antipsychotic agents were developed to promote treatment compliance in patients requiring maintenance treatment for schizophrenia.

METHOD

An analysis of the impact of non-compliance on treatment outcomes in schizophrenia and the advantages and disadvantages of long-acting antipsychotics.

RESULTS

Partial or total non-compliance with oral antipsychotics remains widespread and is associated with significant increases in the risk of relapse, rehospitalization, progressive brain tissue loss and further functional deterioration. Long-acting agents have the potential to address issues of all-cause discontinuation and poor compliance. The development of the first long-acting atypical antipsychotic, which appears to be effective and well tolerated, should further improve the long-term management of schizophrenia.

CONCLUSION

Long-acting agents represent a valuable tool for the management of schizophrenia and merit wider use, especially in light of emerging literature regarding the neuroprotective advantages of atypical antipsychotics over conventional agents in terms of regenerating brain tissue during maintenance therapy.

Cerebral ventricular enlargement in subtypes of chronic schizophrenia

A computed tomographic study of the brain in 55 young men with chronic schizophrenia and 27 age- and sex-matched control subjects showed a significantly higher ventricle-brain ratio (VBR) in the patients with chronic schizophrenia. Using the Tsuang-Winokur criteria, the sample was classified into paranoid and nonparanoid-hebephrenic subtypes. Nonparanoid patients who did not fulfill the criteria for hebephrenia were grouped as a nonparanoid-undifferentiated subtype. All three groups of subtypes had a significantly higher mean VBR than control subjects. Among the schizophrenia subtypes, the paranoid and nonparanoid-hebephrenic groups were not different, and both had a significantly larger mean VBR than the nonparanoid-undifferentiated group. The results suggest that although the extent of ventricular enlargement varies among schizophrenia subtypes, they all show a significant enlargement compared with the control group. Also, in contrast with previous reports linking a high VBR with negative symptoms, poor prognosis, and impaired cognition, the data in this study show the largest mean VBR in the paranoid patients who generally have a good premorbid history, positive symptoms, less impaired cognition, and relatively better prognosis.

Clinical response and plasma levels: effect of dose, dosage schedules, and drug interactions on plasma chlorpromazine levels

Plasma chlorpromazine (CPZ) levels of 50 psychotic inpatients were measured by gas liquid chromatography; the clinical progress of 29 of these patients with acute psychoses was also assessed. CPZ levels of 50-300 ng/ml were usually associated with clinical improvement; there was also a relationship between CPZ levels and increases in certain symptoms. The 50-300 ng/ml level was best attained by doses of 400-800 mg/day. Trihexyphenidyl decreased plasma CPZ by a mean of 44.7% in 12 of 15 patients. A single 400-800-mg dose of CPZ at bedtime produced steady states equal to or better than those achieved with multiple doses. Those patients who failed to attain CPZ levels of more than 70 ng/ml despite doses of 400-1000 mg/day were receiving lithium throughout the study and had discharge diagnoses of manic-depressive psychosis, manic type, and schizo-affective schizophrenia--a finding with implications for future research.

Corpus callosum thickness in chronic schizophrenia

In an effort at replication of the original report (Rosenthal and Bigelow, 1972) of increased callosal thickness in schizophrenic brains, the corpus callosum was measured in a blind study of 64 brains autopsied between the years 1972 and 1976. Diagnosis was established by independent chart review. The mean corpus callosum mid sections of 21 early onset chronic schizophrenic brains were found to have a significantly greater thickness when compared with 8 subjects with late onset schizophrenia, 13 patients with neurological diagnoses, or 14 patients with other psychiatric diagnoses. These studies, if independently confirmed, should provide an impetus for testing the hypothesis that some chronic schizophrenic patients have an illness associated with a pathological process in the corpus callosum.

Hypofrontality and cognitive impairment in schizophrenia: dynamic single-photon tomography and neuropsychological assessment of schizophrenic brain function

Regional cerebral blood flow (rCBF) was assessed in 40 chronic male schizophrenic patients (20 medicated, 20 unmedicated) and 31 matched normal controls with Dynamic Single-photon Emission Computed Tomography (D-SPECT). Blind analyses of normalized color-coded tomograms revealed significant bifrontal and bitemporal rCBF deficits in the patient group. Frontal flow deficits were most prominent in paranoid patients (n = 21) and right temporal deficits were most prominent in nonparanoid patients (n = 19). These relative regional declines were observed within the context of significantly elevated hemispheric blood flow in schizophrenics compared with controls. Reduced left frontal rCBF was associated with neuropsychological impairment on the Wisconsin Card Sorting Test and Luria-Nebraska Battery. Increased hemispheric CBF was correlated with the presence of positive schizophrenic symptoms. Medication status was unrelated to rCBF. These findings demonstrate that hypofrontality has important implications for cognitive function in some schizophrenic individuals.

Proton magnetic resonance spectroscopy (1H MRS) of the hippocampal formation in schizophrenia: a pilot study

BACKGROUND

Recent post-mortem and magnetic resonance imaging (MRI) studies strongly suggest a decrease in the volume of the hippocampus and other limbic temporal structures in schizophrenia. Therefore, we hypothesised that N-acetyl aspartate (NAA) which is found mainly in neurons and which can be measured by proton magnetic resonance spectroscopy (1H MRS) would be decreased in the limbic temporal region in schizophrenia.

METHOD

Consenting subjects fulfilling DSM-III-R criteria for schizophrenia (n = 11) and matched healthy volunteers (n = 11) who were recruited in a tertiary university referral centre, participated in a 1H MRS brain study. Proton MRS spectra were obtained from a 12 cm3 voxel (2 x 2 x 3 cm) in the right and left hippocampus/amygdala region. A researcher blind to the source of the spectra, measured the NAA intensity in all subjects, which were then statistically compared across the two groups.

RESULTS

NAA intensities were significantly reduced in the right hippocampus/amygdala region of schizophrenic patients (P = 0.038). The difference of the left side did not reach significance at the 95% confidence level.

CONCLUSIONS

The findings of decreased NAA in this study suggest that there may be a decrement in neuronal number or tissue volume of the right hippocampal/amygdala region in schizophrenia. Biochemical alterations in the metabolism of NAA in schizophrenia may be an alternative explanation. The findings are consistent with other types of post-mortem and in vivo evidence for hypoplasia of the limbic temporal structures in schizophrenia, postulated to be of neurodevelopmental pathogenesis.

Auditory evoked potentials, clinical vs. research applications

Evidence of abnormal auditory evoked potentials (EPs) in patients suffering from schizophrenia has been accumulating. In spite of the magnitude of the EPs in schizophrenia literature, EPs have not been found to be clinically useful thus far. In this study we attempted to replicate the findings in a large sample of schizophrenia patients, and describe how auditory EPs may be used as supplemental tests in the differential diagnostic process. Five subject groups were formed; paranoid (PAR) and disorganized/undifferentiated (disorg/undiff) schizophrenics, schizoaffective (SA), bipolar, and a normal control group. All patients were stable on medications. Subjects underwent one EP recording session. Classification and regression trees (CART) based on EP amplitudes were used to classify subjects into subgroups. The optimal Bayes classification rule that minimizes the expected misclassification cost was then constructed for various misclassification cost functions. In a standard 'Odd Ball' paradigm the N100 amplitudes were significantly decreased in the disorg/undiff group than in the bipolar or normal subjects. The P200 amplitude was smaller in the PAR, disorg/undiff and the SA groups than in the normal controls. Both the disorg/undiff and the PAR groups had significantly lower P300 amplitudes than the normal controls. Classification rules used to classify subjects into normal or ill were sensitive to the relative cost of misclassifying a subject, as well as the prior clinical probability that this subject was ill. Our data largely agree with the existing literature showing abnormally decreased N100, P200, and P300 amplitudes in schizophrenic patients, particularly the disorg/undiff patients. We conclude that whether EP measures are clinically useful depends on the clinical situation. In particular, the prior probability of the diagnosis in question being present and the cost of misclassifying the patient are critical.

Neuropsychological performance in symptomatic and asymptomatic HIV infection

OBJECTIVE

To examine cognitive function in patients at various stages of HIV infection, and to determine the nature and severity associated with stage of illness.

DESIGN

Subjects were administered an extensive battery of neuropsychological tests.

SUBJECTS

Two hundred and thirty-three HIV-1-infected homosexual/bisexual men and 77 HIV-negative control subjects who had been screened for previous neurological illness. All subjects were volunteers in a longitudinal study of neurobehavioral complications of HIV infection.

RESULTS

Patients with symptomatic infection differed from controls on a large number of measures, and asymptomatic patients had a more circumscribed pattern of deficit. On a summary measure of cognitive impairment, there was a twofold increase in the prevalence of impairment in asymptomatic patients relative to controls, and a fourfold increase in symptomatic patients. Memory and dexterity problems appear to be early features of neurobehavioral dysfunction, and frontal lobe deficits were found in patients with symptomatic infection.

CONCLUSION

These data indicate that there is a steady increase in the prevalence of neurobehavioral abnormalities associated with stage of infection. The pattern of abnormality also varies with disease stage.

The P50 evoked potential component and mismatch detection in normal volunteers: implications for the study of sensory gating

Sensory gating is a complex, multistage, multifaceted physiological function believed to be protecting higher cortical centers from being flooded with incoming irrelevant sensory stimuli. Failure of such mechanisms is hypothesized as one of the mechanisms underlying the development of psychotic states. Attenuation of the amplitude of the P50 evoked potential component with stimulus repetition is widely used to study sensory gating. In the current study, we investigated the responsiveness of the P50 component to changes in the physical characteristics of ongoing trains of auditory stimuli. Forty normal volunteers were studied in a modified oddball paradigm. At all cerebral locations studied, P50 amplitudes were higher in response to infrequent stimuli. We postulate that the increase in P50 amplitude reflects the system's recognition of novel stimuli or "gating in" of sensory input. The ratio of the amplitude of the responses to the infrequent stimuli to those of the frequent stimuli was significantly higher for the posterior temporal regions. This finding provides further evidence that the temporal lobes may be significantly involved in sensory gating processes. Although this study only included normal subjects, the data generated contribute to the understanding of sensory gating mechanisms that may be relevant to psychotic states.

Gender differences in schizophrenia on MRI brain scans

There are many reports of clinical and biological gender differences in schizophrenia. Gender differences in structural brain abnormalities in schizophrenia have been reported on both computed tomographic (CT) and magnetic resonance imaging (MRI) scans. We present here a new MRI study of cerebral structures in schizophrenia. On the basis of previous findings, we hypothesized that schizophrenic males are more likely than females to show smaller brains and larger ventricles compared to their control counterparts. Our results indicated that the opposite was true: schizophrenic females, but not schizophrenic males, had smaller craniums and brains and larger lateral and third ventricles on MRI scans. The possible significance and implications of these data are discussed.

Neuropsychological deficit in schizophrenic subtypes: paranoid, nonparanoid, and schizoaffective subgroups

Schizophrenic patients were carefully diagnosed and screened for a history of neurological disorders. Diagnosis and subtyping was based on DSM-III-R criteria, using the Structured Clinical Interview for DSM-III-R, which was administered by trained interviewers and confirmed by a research psychiatrist. The schizophrenic patients were compared with an age-matched control group on an extensive battery of neuropsychological measures. The undifferentiated/disorganized schizophrenic patients were consistently the most impaired on a broad range of tasks. When the effect of symptom severity and drug level were statistically controlled (analysis of covariance), however, the magnitude and number of differences were substantially reduced. The perseverative error score from the Wisconsin Card Sort Test showed the greatest difference between the groups. However, the strongest and most consistent effects were observed in relation to symptom ratings. These data indicate the importance of controlling for medication and symptom severity, and suggest that current diagnostic classifications may not be the most useful factors for studies of the cognitive correlates of schizophrenia.

Psychopathology in human immunodeficiency virus infection: lifetime and current assessment

The present study determined lifetime and current psychiatric functioning in a sample of homosexual or bisexual men at various stages of human immunodeficiency virus (HIV) infection in order to address several questions regarding the relationship between psychopathology and HIV infection. HIV+ asymptomatic or symptomatic and HIV- homosexual or bisexual men completed self-report measures of psychological and health functioning and participated in structured diagnostic interviews. Additional information regarding HIV-related life events and their potential relationship to onset of disorder and family history of psychiatric disorder were obtained. A high lifetime prevalence of affective and substance use disorder was found, with almost one half of the sample meeting criteria for both disorders. Lifetime affective disorder diagnosis was associated with a positive family history of affective disorder. HIV-related events were most closely associated with onset or recurrence of affective disorder compared with other disorders. Low current rates of psychiatric disorder and levels of emotional distress were found, with no differences in degree of psychiatric adjustment across stage of infection. We conclude that the lifetime prevalence of certain categories of psychiatric disorder is high in both HIV+ and HIV- homosexual samples. Increased rates of psychiatric disorders do not appear to be a consequence of HIV infection. However, episodes of illness, particularly affective disorder, may develop following an HIV-related event such as confirmation of infection. Although symptomatic subjects have more somatic difficulties, there appears to be no relationship between stage of illness and level of emotional distress.

Depression and neuropsychological performance in asymptomatic HIV infection

OBJECTIVE

The authors examined the effect of depression on neuropsychological performance in HIV-infected men. Previous studies have suggested that depression may account for the neuropsychological abnormalities observed in some patients with HIV infection, but few studies have specifically examined this question.

METHOD

An extensive neuropsychological test battery was administered to 121 HIV-seropositive asymptomatic men and 42 HIV-seronegative comparison subjects. The seropositive subjects were grouped into depressed and non-depressed groups on the basis of scores on the Beck Depression Inventory, Hamilton Rating Scale for Depression, and Structured Clinical Interview for DSM-III-R.

RESULTS

Statistical comparisons revealed very few measures on which the depressed seropositive subjects scored significantly worse than either of the nondepressed comparison groups. The nondepressed seropositive group differed consistently from the seronegative comparison subjects on measures of verbal memory and dexterity.

CONCLUSIONS

These data indicate that the subtle neuropsychological abnormalities observed in some asymptomatic HIV-seropositive subjects cannot be attributed to depression. These data also indicate the advantages of a multifaceted approach to assessment of depression.

Major depression and carbon monoxide-induced parkinsonism: diagnosis, computerized axial tomography, and response to L-dopa

A case of major depressive disorder complicated by carbon monoxide (CO)-induced Parkinson's syndrome is reported. Computerized axial tomography (CAT) revealed bilateral globus pallidus necrosis. Clinical, CAT, and neuropathological findings in other cases of CO encephalopathy with and without parkinsonism are reviewed. The utility of CAT in the diagnostic workup and in following clinical course is discussed, as are the difficulties of making a diagnosis of an antecedent primary psychiatric disorder in the presence of neurological and psychiatric sequelae of CO intoxication. There was no clinical response to a tricyclic antidepressant, but both the mood and movement disorders responded fully to L-dopa. The implications of these findings with regard to the central neurochemical pathophysiology in this patient and in major depressive disorder in general are discussed.