This study evaluates the effects of ketamine on healthy and schizophrenic volunteers (SVs)

Several electrical neural oscillatory abnormalities have been associated with schizophrenia, although the underlying mechanisms of these oscillatory problems are unclear. Animal studies suggest that one of the key mechanisms of neural oscillations is through glutamatergic regulation; therefore, neural oscillations may provide a valuable animal-clinical interface on studying glutamatergic dysfunction in schizophrenia. To identify glutamatergic control of neural oscillation relevant to human subjects, we studied the effects of ketamine, an N-methyl-D-aspartate antagonist that can mimic some clinical aspects of schizophrenia, on auditory-evoked neural oscillations using a paired-click paradigm. This was a double-blind, placebo-controlled, crossover study of ketamine vs saline infusion on 10 healthy subjects. Clinically, infusion of ketamine in subanesthetic dose significantly increased thought disorder, withdrawal-retardation, and dissociative symptoms. Ketamine significantly augmented high-frequency oscillations (gamma band at 40-85 Hz, p ¼ 0.006) and reduced lowfrequency oscillations (delta band at 1-5 Hz, po0.001) compared with placebo. Importantly, the combined effect of increased gamma and reduced delta frequency oscillations was significantly associated with more withdrawal-retardation symptoms experienced during ketamine administration (p ¼ 0.02). Ketamine also reduced gating of the theta-alpha (5-12 Hz) range oscillation, an effect that mimics previously described deficits in schizophrenia patients and their first-degree relatives. In conclusion, acute ketamine appeared to mimic some aspects of neural oscillatory deficits in schizophrenia, and showed an opposite effect on scalp-recorded gamma vs low-frequency oscillations. These electrical oscillatory indexes of subanesthetic ketamine can be potentially used to cross-examine glutamatergic pharmacological effects in translational animal and human studies.

Ninety subjects with severe and disabling psychiatric conditions, predominantly schizophrenia, participated in a controlled-outcome trial of the cognitive component of Integrated Psychological Therapy (IPT), a group-therapy modality intended to reestablish basic neurocognitive functions. The cognitive therapy was delivered to subjects in the experimental condition during intensive 6-month treatment periods. Control subjects received supportive group therapy. Before, during, and after the intensive treatment period, all subjects received an enriched regimen of comprehensive psychiatric rehabilitation, including social and living skills training, optimal pharmacotherapy, occupational therapy, and milieu-based behavioral treatment. IPT subjects showed incrementally greater gains compared with controls on the primary outcome measure, the Assessment of Interpersonal Problem-Solving Skills, suggesting that procedures that target cognitive impairments of schizophrenia spectrum disorders can enhance patients' response to standard psychiatric rehabilitation, at least in the short term, in the domain of social competence. There was equivocal evidence for greater improvement in the experimental condition on the Brief Psychiatric Rating Scale disorganization factor and strong evidence for greater improvement on a laboratory measure of attentional processing. There was significant improvement in both conditions on measures of attention, memory, and executive functioning, providing support for the hypothesis that therapeutic procedures that target impaired cognition enhance response to conventional psychiatric rehabilitation modalities over a 6-month timeframe.

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The aim of this study was to examine the potential of serial rCBF studies to directly characterize the regional effects and dynamic time course of the centrally active drug ketamine. The value of a broader application of this technique to other neurally active drugs to characterize the pharmacodynamics of CNS compounds is suggested by these data. Thirteen normal subjects received a 0.3 mg/kg intravenous dose of ketamine over 60 seconds; ten other individuals received placebo in the same manner. For each subject, three baseline PET rCBF scans and seven sequential post-ketamine scans at 10-minute intervals were obtained using H(2)(15)O water. SPM techniques were employed to identify the maxima of any cluster significant by spatial extent analysis at any post-ketamine time point between 0 and 36 min. These extremes from the ketamine group, were identified in placebo scans similarly and grown to a 6x6x12 mm voxel set. The average rCBF values of the ketamine-defined clusters were determined in the drug and placebo conditions at all time points. rCBF across time was plotted for each cluster and compared between drug and placebo. Area under the curve (AUC) was calculated between baseline and 36 minutes. The kinetic characteristics of the ketamine-induced rCBF curves were compared to induced behaviors in each maxima. Ketamine produced distinct patterns of rCBF change over time in different brain regions; maxima within an anatomically defined region responded similarly. Ketamine induced rCBF activations in anterior cingulate, medial frontal and inferior frontal cortices. All maxima with a relative flow reduction with ketamine were in the cerebellum. The pattern of all activations and suppressions was monophasic with the peak changes at 6-16 minutes. In preliminary analysis, individual C(max) and AUC of maxima in the anterior cingulate/medial frontal region tended to correlate with the mild psychotomimetic action of ketamine; whereas, there was no tendency toward correlation with this psychological change in cerebellar maxima. The direct action of a centrally active drug can be assessed regionally and dynamically in brain using rCBF and a scan sequence optimally timed to complement the drug's time course. Ketamine pharmacodynamic response can be related to concurrent behavioral changes, tending to link the behavior with a brain region. This experimental design provides direct characterization of drug action in the CNS in ways heretofore unavailable.

The regional neuronal changes taking place in the early and late stages of antipsychotic treatment are still not well characterized in humans. In addition, it is not known whether these regional changes are predictive or correlated with treatment response. Using PET with 15O, we evaluated the time course of regional cerebral blood flow (rCBF) patterns generated by a first (haloperidol) and a second (olanzapine) generation antipsychotic drug (APD) in patients with schizophrenia during a 6 week treatment trial.Patients were initially scanned after withdrawal of all psychotropic medication (two weeks), and then blindly randomized to treatment with haloperidol (n=12) or olanzapine (n=17) for a period of 6 weeks. Patients were scanned again after 1 and 6 weeks of treatment. All assessments, including scanning sessions, were obtained in a double-blind manner.As hypothesized, we observed rCBF changes that were common to both drugs, implicating cortico-subcortical and limbic neuronal networks in antipsychotic action. In addition, in these regions, some patterns seen at week 1 and 6 were distinctive, indexing neuronal changes related to an early (ventral striatum, hippocampus) and consolidated [anterior cingulate/medial frontal cortex (ACC/MFC)] stage of drug response. Finally, both after 1 and 6 weeks of treatment, we observe differential patterns of rCBF activation between good and poor responders. After one week of treatment, greater rCBF increase in ventral striatum and greater decrease in hippocampus were associated with good response.

We report on the correlations between whole brain rCBF and the positive and negative symptoms of schizophrenia in two cohorts of patients who were scanned while free of antipsychotic medication. We hypothesized that positive symptoms would correlate with rCBF in limbic and paralimbic regions, and that negative symptoms would correlate with rCBF in frontal and parietal regions. Both cohorts of patients with schizophrenia (Cohort 1: n ¼ 32; Cohort 2: n ¼ 23) were scanned using PET with H 2 15O while free of antipsychotic medication for an average of 21 and 15 days, respectively. Both groups were scanned during a resting state. Using SPM99, we conducted pixel by pixel linear regression analyses between BPRS scores and whole brain rCBF. As hypothesized, positive symptoms correlated with rCBF in the anterior cingulate cortex (ACC) in a positive direction and with the hippocampus/parahippocampus in a negative direction in both patient groups. When the positive symptoms were further divided into disorganization and hallucination/delusion scores, similar positive correlations with ACC and negative correlations with hippocampus rCBF were found. In both cohorts, the disorganization scores correlated positively with rCBF in Broca's area. As expected, negative symptoms correlated inversely with rCBF in frontal and parietal regions. This study provides evidence that limbic dysfunction may underlie the production of positive symptoms. It suggests that abnormal function of Broca's area may add a specific language-related dimension to positive symptoms. This study also provides further support for an independent neurobiological substrate of negative symptoms distinct from positive symptoms. The involvement of both frontal and parietal regions is implicated in the pathophysiology of negative symptoms.

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