Illness-course modulates suicidality-related prefrontal gray matter reduction in women with bipolar disorder.

OBJECTIVE: Explore interrelationships between suicide attempt history (Objective 1) or suicide attempt severity (Objective 2) with prefrontal cortex gray matter (PFCGM ) volume and illness-course in patients with bipolar disorder (BD). METHOD: Ninety-three women with BD-I or -II diagnosis (51 with and 42 without suicide attempt history) underwent structural MRI and filled out questionnaires. Measured were GM volumes of 11 PFC regions, BD illness-course, and attempt history and severity. Effects were examined with repeated measures GLM or logit analyses. RESULTS: Objective 1: Attempt history was associated with increased trait impulsivity and aggression, and higher prevalence of BD-I, past drug use disorder, and past psychiatric hospitalization. PFCGM volume was lower in patients with than without attempt history in those with past psychiatric hospitalization. PFCGM volume was higher in patients with than without attempt history in those without hospitalization. Higher trait aggression predicted attempt history. Objective 2: Increased frontal pole volume and younger age at first hospitalization predicted many suicide attempts. CONCLUSION: Attempt history in patients with BD related to PFCGM volume reduction or increase. Volume modulation by psychiatric hospitalization could reflect effects of illness-course or care. Attempt severity was not related to volume reduction. Research on suicidality-brain relationships should include illness-course and attempt severity measures.

Interactions between bipolar disorder and antisocial personality disorder in trait impulsivity and severity of illness.

OBJECTIVE: We investigated trait impulsivity in bipolar disorder and antisocial personality disorder (ASPD) with respect to severity and course of illness. METHOD: Subjects included 78 controls, 34 ASPD, 61 bipolar disorder without Axis II disorder, and 24 bipolar disorder with ASPD, by Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders (DSM-IV) (SCID-I and -II). Data were analyzed using general linear model and probit analysis. RESULTS: Barratt Impulsiveness Scale (BIS-11) scores were higher in ASPD (effect sizes 0.5-0.8) or bipolar disorder (effect size 1.45) than in controls. Subjects with both had more suicide attempts and previous episodes than bipolar disorder alone, and more substance-use disorders and suicide attempts than ASPD alone. BIS-11 scores were not related to severity of crimes. CONCLUSION: Impulsivity was higher in bipolar disorder with or without ASPD than in ASPD alone, and higher in ASPD than in controls. Adverse effects of bipolar disorder in ASPD, but not of ASPD in bipolar disorder, were accounted for by increased impulsivity.

Attention deficit and impulsivity: selecting, shifting, and stopping.

The present selective review addresses attention, inhibition, and their underlying brain mechanisms, especially in relation to attention deficit/hyperactivity disorders (AD/HD), and the effects of methylphenidate. In particular, event-related potential (ERP) studies suggest a deficit in the early-filtering aspect of selective attention in children with AD/HD. Results from stop tasks are consistent with impairments in stopping performance in AD/HD, but in children (as opposed to adults) these effects cannot be easily dissociated from more general impairments in attention to the task, and therefore an interpretation in terms of inhibitory control is not straightforward. On the other hand, the beneficial effects of methylphenidate are more specific to stopping, and there are no clearcut effects of methylphenidate on measures of selective attention. Even when group differences pertain specifically to stopping performance (as with adults with AD/HD), ERP evidence suggests at least a partial contribution of differences in switching attention to the stop signal, as revealed in measures of sensory cortex activation. ERP evidence from cued go/nogo tasks underlines the importance of taking into account the contribution of higher order control processes involved in anticipation of and preparation for task stimuli. It suggests that in certain conditions, expectancy, rather than response bias, contributes to increased behavioral response tendencies, and that a presumed index of response inhibition, the nogo N2, may rather reflect conflict monitoring. In sum, direct reflections of brain activity suggest that mechanisms of expectation and attention, rather than of response bias or inhibitory control, govern behavioral manifestations of impulsivity.

Differences between low and high trait impulsivity are not associated with differences in inhibitory motor control.

OBJECTIVE: The present study investigates whether there is an association between trait impulsivity in the normal population and inhibitory motor control as assessed by the stop task. METHOD: Low- and high-impulsive participants (as assessed by the I7 questionnaire; both groups n = 31) performed the stop task. Differences in performance were analyzed by an independent samples t-test. Furthermore, a short meta-analysis was performed on this study and three previous studies with a similar aim. RESULTS: The low- and high-impulsive groups did not differ on the speed to stop the response (SSRT). However, the meta-analysis revealed that high-impulsives are marginally slower in stopping than low-impulsives (effect size = -0.26, p= 0.06). CONCLUSIONS: There is only minor evidence that impulsivity inthe common population is associated with poor inhibitory motor control.

Somatotropic-axis deficiency affects brain substrates of selective attention in childhood-onset growth hormone deficient patients.

Reduced levels of growth hormone (GH) and insulin-like growth factor-1 (IGF-1) are associated with deteriorated cognitive performance in senescence. Little work has been done on the effect of GH and IGF-1 on a crucial aspect of cognition, selective attention. This study investigated the effect of GH/IGF-1 on performance and brain potentials (EEG) during a selective-attention task in patients with low levels of GH and IGF-1 (childhood-onset growth hormone deficiency) compared to healthy controls. Detection of occasional visual target patterns was impaired in patients. This was paralleled by a reduction in an attention-related brain potential, which has been associated previously with anterior cingulate cortex functioning.

On the processing of spatial frequencies as revealed by evoked-potential source modeling.

OBJECTIVES AND METHODS: Visually evoked potentials (VEPs) are known to be sensitive to spatial frequency, especially in the time range between 50 and 100 ms post-stimulus. In two experiments we localized the cortical activity elicited by stimuli of varying spatial frequency in scalp-recorded brain potentials, using multi-electrode recordings and dipole-source analysis. RESULTS: Low spatial frequencies (<1 c/d) activated relatively lateral occipital areas, the orientation of the neural ensembles involved being predominantly perpendicular to the scalp surface. In contrast, high spatial frequencies (>4 c/d) induced activation of more medial occipital areas with the predominant orientation of the sources being much more parallel to the scalp surface. Furthermore, at about 100 ms latency the lateral-occipital response to low spatial frequencies was stronger in the right hemisphere; no such asymmetry was found for the responses to the high spatial frequencies. These findings were consistent across varying recording conditions, individual subjects, subject populations, stimulus characteristics (grating orientation, grating vs. checkerboard), and task conditions (active vs. passive). CONCLUSION: The results indicate that there are differences in sensitivity to specific spatial frequencies between primary and secondary visual areas, as well as between the right and the left hemispheres.