Malingering in the Psychiatric Emergency Department: Prevalence, Predictors, and Outcomes.

OBJECTIVE: Malingering is commonly encountered in the psychiatric emergency department, yet little is known about its prevalence, objectives, or effect on patient management. This study analyzed characteristics of malingering and patient disposition in a 24/7-staffed comprehensive psychiatric emergency program (CPEP) and created predictive models to understand malingering and its effect on physician decision making. METHODS: Attending psychiatrists completed questionnaires after comprehensive assessments of 405 patients presenting to the CPEP during the 1-month study, recording suspicion of malingering, symptoms malingered, associated secondary gains, demographic characteristics, and initial disposition decision. Analyses examined characteristics associated with degree of malingering suspicion and disposition. RESULTS: Malingering was suspected among one-third of patients, and 20% were strongly or definitely suspected of malingering. High suspicion was associated with malingering of multiple symptoms and was likely to result in immediate discharge. Lower suspicion was associated with being held for further observation. Among patients for whom suspicion of malingering was high, malingering was most frequent for suicidal ideation (58%) and depression (39%); malingering was often used to seek hospital admission (54%) and to stay in the CPEP (35%); malingering was sometimes used to seek multiple secondary gains (25%); and malingering often involved multiple symptoms (44%). Patients for whom suspicion was high had an admission rate of 4%. Among patients suspected of malingering, three variables each independently increased the likelihood of hospital admission: seeking social work or housing services, seeking admission, and malingering of suicidal ideation. CONCLUSIONS: Malingering was prevalent in the psychiatric emergency department, and suspicion of malingering was associated with disposition differences. Disposition was significantly influenced by both suspicion of malingering and the gains sought by patients.

Evidence for an extracellular zinc-veneer in rodent brains from experiments with Zn-ionophores and ZnT3 knockouts.

Ionic zinc is found at a high concentration in some glutamatergic vesicles of the mammalian brain. Ionic zinc is also found chelated to macromolecules in the extracellular space, constituting what has been called the "zinc veneer". In this communication we show that the zinc ionophore, pyrithione, can be used to demonstrate the presence of the veneer. Application of pyrithione without added ionic zinc to rodent hippocampal slices mobilizes extracellular zinc, which can be detected intracellularly by the zinc probe FluoZin-3. In addition, we show that ZnT3 null mice, which lack the transporter responsible for stocking synaptic vesicles, nevertheless do have a zinc veneer, albeit diminished compared to wild type animals. The presence of the zinc veneer in ZnT3 null mice may account for the absence of any marked deficit in these animals.

Differential transition metal uptake and fluorescent probe localization in hippocampal slices.

Metals are taken up by the combined action of metal transporters and ion channels. In this communication we have measured the uptake of the biologically important transition metals Mn, Fe, Co, Ni, Cu, Zn and Cd by rat and mouse hippocampal slices using the fluorescent probes FluoZin-3 (FZ3) and Newport Green (NPG), introduced by acetoxymethyl ester (AM) loading. The combination of metals and probes is also used to attempt to localize cellular sites into which metals translocate. We show that FZ3 and NPG partition into different cellular compartments; FZ3 into neuropil, whereas NPG localizes in neuropil and compartments within the cell bodies of neurons. Ni, Zn and Cd pass across the plasma membrane and then accumulate in intracellular vesicles and within intracellular membranes of cell bodies. The latter accumulate Cd, while synaptic vesicles take up Co. The passage of Mn, Cu and Fe into cells can be detected but there is some uncertainty about their disposition within the cell. All of our experiments are consistent with metals accumulating in intracellular compartments rather than the cytoplasm. Whether and to what extent there are transient elevations of free zinc levels in the cytoplasm remains unclear.

Zinc is externalized rather than released during synaptic transmission.

The synaptic vesicles of some glutamatergic terminals contain a high concentration of zinc that serves functions that remain obscure. In this publication we have used the membrane permeant zinc fluophore, ZnAF-2 to determine if zinc is released during the course of synaptic transmission. Stimulation of the slices with either high potassium or electrically, leads to an increase in fluorescence that long outlasts the stimulus and remains elevated for many minutes. We demonstrate that this response is inconsistent with the free release of zinc but is with the presentation of zinc coordinated to macromolecules within the exocytosed vesicles to the extracellular space; a process we term 'externalization'. Our data suggests a novel mechanism of synaptic transmission at zinc-rich glutamatergic terminals that distinguishes them from their metal free counterparts.

The interplay between inorganic phosphate and amino acids determines zinc solubility in brain slices.

Inorganic phosphate (Pi) is an important polyanion needed for ATP synthesis and bone formation. As it is found at millimolar levels in plasma, it is usually incorporated as a constituent of artificial CSF formulations for maintaining brain slices. In this paper, we show that Pi limits the extracellular zinc concentration by inducing metal precipitation. We present data suggesting that amino acids like histidine may counteract the Pi-induced zinc precipitation by the formation of soluble zinc complexes. We propose that the interplay between Pi and amino acids in the extracellular space may influence the availability of metals for cellular uptake.