PSYCHOPHYSICAL, PSYCHOMETRIC AND BIOCHEMICAL COMPARISONS OF BIPOLAR AFFECTIVE DISORDERS AND A NORMAL CONTROL GROU

Psychopathologists have searched for markers which would distinguish between patient populations and normal control groups. If found, such markers would not only aid in the identification of psychiatric disorders, but may also shed light on the etiology of the disorder.;Researchers have found that a simple reaction time (RT) procedure can reliably distinguish between schizophrenics and normal controls. Investigators manipulate preparatory interval (PI) length across trials by presenting either a regular or an irregular series. A regular series involves the presentation of a block of RT trials with identical PIs between the warning signal and the imperative stimulus. An irregular series consists of randomized presentations of several different PI lengths. Reaction times for normal subjects are found to be consistently faster during the regular series as opposed to the irregular series. Schizophrenics show this effect only when the PI lengths are relatively short. Schizophrenics' performance decreases as PI lengthens during the regular series. When RT is plotted as a function of PI type across PI length, the functions crossover at approximately the five second mark; hence the term crossover effect. The crossover effect has also been observed in relatives of schizophrenics, college students selected to be at risk for schizophrenia, and college students selected to be at risk for bipolar disorder, suggesting that it is not specific to schizophrenia. Researchers have also searched for biochemical markers which may distinguish patients from normal controls. Platelet MAO and plasma DBH have both been reported to be low in bipolar patients.;The current study examined RT, platelet MAO levels, plasma DBH levels, and the personality measure of sensation seeking in 16 male bipolar patients and 17 male controls.;Bipolar patients were found to have slower RTs and also demonstrated the crossover effect as compared to the control group. Platelet MAO and plasma DBH levels did not differ between the groups. Bipolar patients scored higher than the controls on the Disinhibition subscale of the Sensation Seeking Scale.;The RT data is discussed in terms of the task specific arousal and its effect on performance.