Joseph I. Tracy

Polydipsia and water intoxication in psychiatric patients: a review of the epidemiological literature.

Polydipsia among chronic psychiatric patients is poorly understood and underdiagnosed. It may have three stages: simple polydipsia, polydipsia with water intoxication, and physical complications. Epidemiological surveys have used staff reports and polyuria measures to identify polydipsic patients. Water intoxication has been screened by chart review, weight, or serum sodium data. According to these surveys, polydipsia, not explained by medically induced polyuria, may be present in more than 20% of chronic inpatients. Up to 5% of chronic inpatients had episodes of water intoxication although mild cases may have been missed. Single time point surveys show that 29% of polydipsic patients had presented water intoxication. Methodologically limited clinical studies suggest that polydipsia with water intoxication rather than simple polydipsia may be associated with poor prognosis in schizophrenia. Epidemiological surveys found polydipsia with water intoxication to be associated with chronicity, schizophrenia, smoking, some medications, male gender, and white race. New pathophysiological models need to elucidate these findings.

The serotonin hypothesis of aggression revisited

Many contemporary theorists believe serotonin (5-HT) neurotransmitter functioning plays a role in the regulation of human aggressive behavior. We argue that the evidence supporting this 5-HT hypothesis of human aggression is less compelling than commonly assumed, due to (a) conflicting study results, and (b) significant methodological limitations of existing studies. Recent models that integrate the role of psychological and contextual variables in 5-HT--associated aggression are reviewed. The need to incorporate psychometrically sound measures of aggression in 5-HT studies, to use experimental and longitudinal designs, and to test hypotheses drawn from multifactorial models in future research is advocated.

Functional localization of a “time keeper” function separate from attentional resources and task strategy

The functional neuroanatomy of time estimation has not been well-documented. This research investigated the fMRI measured brain response to an explicit, prospective time interval production (TIP) task. The study tested for the presence of brain activity reflecting a primary time keeper function, distinct from the brain systems involved either in conscious strategies to monitor time or attentional resource and other cognitive processes to accomplish the task. In the TIP task participants were given a time interval and asked to indicate when it elapsed. Two control tasks (counting forwards, backwards) were administered, in addition to a dual task format of the TIP task. Whole brain images were collected at 1.5 Tesla. Analyses (n = 6) yielded a statistical parametric map (SPM ¿z¿) reflecting time keeping and not strategy (counting, number manipulation) or attention resource utilization. Additional SPM ¿z¿s involving activation associated with the accuracy and magnitude the of time estimation response are presented. Results revealed lateral cerebellar and inferior temporal lobe activation were associated with primary time keeping. Behavioral data provided evidence that the procedures for the explicit time judgements did not occur automatically and utilized controlled processes. Activation sites associated with accuracy, magnitude, and the dual task provided indications of the other structures involved in time estimation that implemented task components related to controlled processing. The data are consistent with prior proposals that the cerebellum is a repository of codes for time processing, but also implicate temporal lobe structures for this type of time estimation task.

Depression and category learning.

This article explores the relationship between depression and category learning. We predicted that depression would impair categorization performance on criteria-attribute tasks, which require systematic hypothesis testing, but not on family-resemblance tasks, which allow processing strategies that are likely preserved in depression. These predictions were confirmed in 2 experiments using different stimuli, tasks, and S populations. We discuss some implications of the empirical connections among depression, the use of less sophisticated cognitive strategies, and category learning.

The selective effects of alcohol on automatic and effortful memory processes.

Automatic and effortful memory processes were evaluated in a 2-session, within-subjects design involving an alcohol challenge and a no-alcohol condition. Free recall of a 90-word list measured effortful processing. Estimation of word frequency from the same list measured automatic processing. Acute intoxication was hypothesized to diminish effortful but not automatic memory processes. Healthy, male volunteers (n = 36) completed the 2 conditions 1 week apart. Presentation frequency influenced both free recall and frequency estimation, with both measures increasing as presentation frequency increased. Free recall was significantly lower in the alcohol than in the no-alcohol condition, but frequency estimation was not differentially affected. The data showed that an alcohol challenge dissociated automatic and effortful memory processes in volunteers. The authors discuss potential neurobiological substrates that may account for alcohols selective disruption of effortful, verbal, episodic memory processing.

Neuropsychology of dual diagnosis: Understanding the combined effects of schizophrenia and substance use disorders

Abstract Empirical studies of cognitive functioning in patients suffering from schizophrenia and a substance use disorder are lacking. Consensus exists that schizophrenia is a neurobehavioral disorder with cognitive deficits. With this ready explanation for cognitive impairment in schizophrenia, there exists the possibility that other treatable sources of cognitive decline in schizophrenia, such as substance abuse, may be ignored. The cognitive impairments (e.g., abstraction, selective attention, effortful processing, episodic memory and denial of deficits/illness) and biologic abnormalities (e.g., reduced P300 amplitude, enlarged ventricles, and hypofrontality) common to both schizophrenia and substance use disorders are reviewed. Differences in the cognitive status of the disorders are also noted. Factors altering the cognitive status of these patients are discussed, and seven potential frameworks are offered for conceptualizing the etiologic relation and cognitive impact of these disorders.

Assessing the relationship between craving and relapse.

The value of craving as a construct in the substance use disorders literature stems from its purported ability to predict actual alcohol or psychoactive drug consumption. Empirical reports of cravings relationship to actual use, however, are quite mixed. It is argued that cravings relationship to use variables such as relapse will remain unclear until individual differences related to acting on craving are considered. Such potential mediators of cravings relationship to relapse, such as impulsivity, are evaluated. The implications of this argument for the construct of craving are discussed.

A comparison of reading and demographic-based estimates of premorbid intelligence in schizophrenia

Estimating premorbid intelligence in schizophrenia is difficult because the illness affects aspects of premorbid and postmorbid functioning. We evaluated two qualitatively different estimates of premorbid intelligence in a sample of schizophrenia patients and tested whether: (1) the two indices were related and produced similar IQ estimates, and (2) either index was related to a measure of cognitive deterioration. The Barona Index (BI, a demographically-based instrument) and the National Adult Reading Test (NART, a reading test of irregularly-spelled words) were utilized. Subjects (n = 40) were adult neuroleptic-medicated inpatients with a DSM-III-R diagnosis of chronic schizophrenia (n = 35) or schizoaffective disorder (n = 5). Paired t-tests revealed statistically equivalent BI and NART estimates for Full Scale and Verbal IQs, but significantly higher NART Performance IQs (t[35] = -3.34, p < 0.01). Correlational analyses suggested the two indices were associated but shared modest variance. BI correlations revealed expected associations with education and social position. NART IQs were related to education and a measure of cognitive status. Regression analyses supported the association between NART estimates and cognitive deterioration. Results suggest BI may be a better estimate of premorbid intelligence in schizophrenia as it is less influenced by potential consequences of the disease.

CLOCK DRAWING IN SCHIZOPHRENIA

The Clock Drawing Test, a task sensitive to cognitive decline in neurological groups, was administered to 27 patients with schizophrenia. Clock drawings were scored for over-all global performance and the frequency of specific qualitative errors. Mean global performance scores indicated a small proportion of the sample was below the threshold typically used to identify dementia, and the patients displayed qualitative Clock Drawing deficits not fully represented in the global performance measure. Qualitative analyses indicated that size errors, graphic difficulty, and spatial planning problems were most common. Lastly, duration of illness was not related to global performance, suggesting that the latter might not reflect deterioration but the stable trajectory of impairment that may be constant through the schizophrenia illness.

Investigation of alternating and continuous experimental task designs during single finger opposition fMRI: a comparative study.

The purpose of this study was to empirically investigate and compare the effects of alternating and continuous experimental task designs on blood oxygenation level dependent (BOLD) signal contrast. Six healthy volunteers underwent single-finger opposition functional magnetic resonance imaging (fMRI) using T2*-weighted echo planar imaging technique on a 1.5 T MR scanner. Two different acquisition patterns were tested: alternating (ABABAB) and continuous (AAABBB), rest: A, activation: B. The BOLD signal contrast within a primary motor cortex region of interest (ROI) was evaluated using normalized t-values (z-scores) and mean region of interest (ROI) intensity for the two patterns. Analysis of variance (ANOVA) on ROI mean z-score and signal intensities demonstrate that the alternating pattern of administering rest and activation epochs produced a more robust statistical difference than a continuous pattern. The results showed that different patterns of acquisition yield differences in the BOLD signal at field strength of 1.5 T, and that an alternating task design can be considered more optimal than a continuous task design.