Compound measure of hand-foot-eye preference masked opposite turning behavior in healthy right-handers and non-right-handers: technical comment on Mohr et al. (2003).

A previous article reported opposite turning behavior in right-handers and non-right-handers (C. Mohr. T. Landis, H. S. Bracha, & P. Brugger, 2003). This observation appears contradictory to the 1st study on long-term spontaneous turning behavior in healthy participants (H. S. Bracha, D. J. Seitz, J. Otemaa, & S. D. Click, 1987). These latter authors found a complex interaction between hemispheric dominance, preferred turning side, and sex. C. Mohr et al. (2003) argued that the differentiation of the population in hemisphere-dominant groups by a compound measure of hand-foot-eye preference might have masked their recent finding. Thus, this commentary presents a reanalysis of the original data set (H. S. Bracha et al., 1987). Replicating recent observation, right-handers preferred left-sided turns; and non-righthanders, right-sided turns. This replication strengthens the proposition that handedness and turning behavior might depend on interhemispheric dopamine asymmetries.

Human side preferences in three different whole-body movement tasks.

Animals turn away from the hemisphere with the more active dopamine (DA) system. For humans, a similar relationship has been assumed. However, results from independent studies were obtained from different tasks and indicated different side preferences. To investigate side preferences between different tasks within the same subject, we assessed in 36 healthy research participants (20 women) (1) long-term spontaneous turning (number of 360 degree turns during 20 h), (2) veering (lateral deviations during walking blindfolded straight forward) and (3) stepping (deviations while stepping blindfolded on a given spot) behavior. We observed a left-sided preference for long-term spontaneous turning behavior and no significant side preference for veering and stepping behavior. The absence of consistent side preferences suggests that DA does not equally control lateralized whole-body movements. We propose that visual control enhanced left-sided movement preferences, probably through an enhanced contribution of the right hemisphere to visuo-spatial behavior. Recently, we reported [Neurosci. Lett. 339 (2003) 115] that levodopa supplementation decreases right-sided veering tendencies, while stepping behavior was unaffected by substance intake. We suggest that veering tendencies, which appeared equally pronounced in either direction, are under dopaminergic control as long as attention is directed towards extrapersonal space. Side preferences in lateralized whole-body movement tasks are thus neither comparable between tasks nor within subjects. We conclude that experimental parameters such as visuo-spatial control and spatial task demands (veering is directed to extrapersonal space and stepping to peripersonal space) determine whether or not the DA system is involved.

The STRS (shortness of breath, tremulousness, racing heart, and sweating): A brief checklist for acute distress with panic-like autonomic indicators; development and factor structure.

BACKGROUND: Peritraumatic response, as currently assessed by Posttraumatic Stress Disorder (PTSD) diagnostic criterion A2, has weak positive predictive value (PPV) with respect to PTSD diagnosis. Research suggests that indicators of peritraumatic autonomic activation may supplement the PPV of PTSD criterion A2. We describe the development and factor structure of the STRS (Shortness of Breath, Tremulousness, Racing Heart, and Sweating), a one page, two-minute checklist with a five-point Likert-type response format based on a previously unpublished scale. It is the first validated self-report measure of peritraumatic activation of the autonomic nervous system. METHODS: We selected items from the Potential Stressful Events Interview (PSEI) to represent two latent variables: 1) PTSD diagnostic criterion A, and 2) acute autonomic activation. Participants (a convenience sample of 162 non-treatment seeking young adults) rated the most distressing incident of their lives on these items. We examined the factor structure of the STRS in this sample using factor and cluster analysis. RESULTS: Results confirmed a two-factor model. The factors together accounted for 68% of the variance. The variance in each item accounted for by the two factors together ranged from 41% to 74%. The item loadings on the two factors mapped precisely onto the two proposed latent variables. CONCLUSION: The factor structure of the STRS is robust and interpretable. Autonomic activation signs tapped by the STRS constitute a dimension of the acute autonomic activation in response to stress that is distinct from the current PTSD criterion A2. Since the PTSD diagnostic criteria are likely to change in the DSM-V, further research is warranted to determine whether signs of peritraumatic autonomic activation such as those measured by this two-minute scale add to the positive predictive power of the current PTSD criterion A2. Additionally, future research is warranted to explore whether the four automatic activation items of the STRS can be useful as the basis for a possible PTSD criterion A3 in the DSM-V.

Opposite turning behavior in right-handers and non-right-handers suggests a link between handedness and cerebral dopamine asymmetries.

The strong right hand preference in humans remains a riddle; no lateralized behavior other than fine finger dexterity relates to it. The relation between handedness and language dominance may be far weaker than currently judged; after all, both right-handers and non-right-handers utilize the left brain for speech. There is, however, a lateralized motor preference in animals, turning behavior, that is strongly associated with hemispheric dopamine (DA) asymmetries. Turning consistently occurs towards the side with less DA. The authors tested 69 right-handers and 24 non-right-handers with a device recording spontaneous turning behavior for 20 hr within 3 days. Findings indicate that right-handers preferred left-sided turning and non-right-handers preferred right-sided turning. This result suggests a link between handedness and DA asymmetries.

Congenital dermatoglyphic malformations and psychosis: a twin study.

OBJECTIVE: In a previous twin study, congenital dermatoglyphic abnormalities, such as ridge dissociations and abnormalities of palmar flexion creases, were more prevalent in twins with psychotic and related disorders than in comparison twins. This study was an attempt to replicate that finding in an independent study group. METHOD: Ridge dissociations and abnormal palmar flexion creases were assessed in monozygotic pairs concordant (19 pairs) and discordant (31 pairs) for psychosis and related disorders. RESULTS: The presence of either ridge dissociations or abnormal palmar flexion creases was higher in the combined group of affected concordant and discordant twins (37.7%), than in the nonaffected discordant twins (20.0%; odds ratio=2.4). In the discordant pairs, the presence of either abnormality was strongly associated with psychotic disorder (odds ratio=3.0). CONCLUSIONS: Factors affecting early fetal development may increase the risk for psychotic disorder. Differential exposure to such early risk factors may contribute to twin discordance for psychotic disorder.

Medicated chronic schizophrenic patients do not demonstrate left turning asymmetry.

Twenty-seven medicated chronic schizophrenic female patients were tested for right or left turning behavior. No substantial right or left asymmetry was found, nor did the addition of the indirect dopaminergic agonist amantadine influence these results. Previous studies demonstrated left circling preference in chronic unmedicated schizophrenics and it seems that this previous finding is abolished by neuroleptic treatment. However, our patients were all females and further research with a heterogenous group of schizophrenic patients is needed.

Prenatal growth markers in schizophrenia: a monozygotic co-twin control study.

OBJECTIVE: This co-twin study investigated monozygotic twins who were discordant for schizophrenia for evidence of prenatal growth differences between the affected and well co-twins. METHOD: Four dermatoglyphic markers of prenatal growth were obtained by established procedures from 26 monozygotic twin pairs discordant for schizophrenia, 13 monozygotic twin pairs concordant for schizophrenia, and several normal monozygotic twin samples. RESULTS: The a-b ridge count differences between the affected and well co-twins were greater than those found for concordant and normal monozygotic pairs. In comparison with their well co-twins, the affected twins, in discordant pairs, had developed fewer epidermal ridges in the a-b interdigital area of their right palms. In contrast, no significant differences were found between the affected twins and their well co-twins on markers associated with fetal development before 13 or after 15 weeks estimated gestational age. CONCLUSIONS: Because the a-b ridges are known to complete development between 13 and 15 weeks estimated gestational age, the results provide physical evidence suggesting that the schizophrenia-affected monozygotic twins alone experienced a time-specific and time-limited dysgenesis during this time. Commonalities in the ontogeny of epidermal and neurological structures are discussed.

Racial differences in the diagnosis of psychosis.

In clinical populations, it has been reported that African-American patients are more likely to receive a diagnosis of schizophrenia than similar Caucasian patients. Factors contributing to this racial discrepancy are poorly defined. The authors examined the hypothesis that racial differences in severity of first-rank symptoms of schizophrenia contribute to this diagnostic difference. Patients were recruited as part of the DSM-IV Field Trial for Schizophrenia and Other Psychotic Disorders, and evaluated using a structured rating instrument. Symptom and diagnostic comparisons were performed between black and white patients. Black patients were significantly more likely than white patients to be diagnosed with schizophrenia and less likely with psychotic depression. Racial differences in symptom profiles were observed with black patients demonstrating more severe psychotic symptoms, in general, and first-rank symptoms, specifically. There were no racial differences in rates of affective syndromes or severity of affective symptoms. Racial disparity in diagnosis of psychotic patients may be in part secondary to more severe first-rank symptoms in black patients, causing clinicians to stray from DSM-III-R criteria.

An automated electronic method for quantifying spinning (circling) in children with autistic disorder.

This pilot study examined and quantified rotational asymmetry (the tendency to turn preferentially to the right or left side). An automated device was used to measure turning (circling) in 9 children with autism and 27 normal control subjects and confirmed clinical observations of stereotypical spinning behavior in patients with autism. This behavior was significantly preferential toward the left side relative to control subjects (P = 0.0009, two-tailed). Group membership accounted for approximately 40% of variance. Although the precise causes of autism are not known, these preliminary data suggest that the spinning behavior often seen in children with neurodevelopmental disorders can be reliably measured. Furthermore, spinning in autism may most often manifest as specific right-hemispace neglect.

Prenatal development of monozygotic twins and concordance for schizophrenia.

While twin concordances for schizophrenia have been used to estimate heritability and to develop genetic models, concordances in subtypes of monozygotic (MZ) twins can also be used to investigate the influence of prenatal development in the etiology of mental illness. We used within-pair variability and mirroring of fingerprints to estimate retrospectively the placentation status of concordant and discordant MZ twins. The results indicate that concordant MZ pairs were more likely to have been monochorionic (MC) and to have shared a single placenta, whereas discordant MZ pairs appear more likely to have been dichorionic (DC) with separate placentas. Pairwise concordances for MZ twins without MC markers averaged 10.7 percent. In contrast, concordances for MZ twins with one or more MC markers averaged 60 percent. This suggests that simple MZ concordance rates may overestimate schizophrenia heritability and that prenatal development may also be important in the etiology of schizophrenia. Because MC (but not DC) twins usually share fetal blood circulation and hence are likely to share infections, these results are consistent with the hypothesis that fetal infections may be a significant etiological factor in schizophrenia.

Preliminary evidence for an association between minor physical anomalies and second trimester neurodevelopment in schizophrenia.

Two types of markers, dermatoglyphics and minor physical anomalies, have been used as indicators of problems with fetal neurodevelopment in schizophrenia. The degree to which these markers overlap is not known. While it is agreed that abnormal dermatoglyphics reflect early second trimester maldevelopment, the timing of the development of minor physical anomalies has not been determined. Forty-six schizophrenic patients received assessments for minor physical anomalies, dermatoglyphics (right-left ridge count asymmetry and total finger ridge count), and information processing. Higher scores for minor physical anomalies were associated with greater dermatoglyphic asymmetry. Patients who had both types of indicators (high minor physical anomalies and dermatoglyphic asymmetry) did not differ on information-processing measures from patients who had neither. On the basis of the timing of dermatoglyphic development (weeks 14-22 of gestation), the association between minor physical anomalies and dermatoglyphic asymmetry suggests that the relatively high rate of minor physical anomalies observed in schizophrenia can be considered to reflect at least second trimester maldevelopment.

Phencyclidine and (+)-MK-801-induced circling preference: correlation with monoamine levels in striatum of the rat brain.

Phencyclidine (PCP; angel dust) is a drug of abuse known to produce a behavioral state in humans resembling schizophrenia/psychosis. PCP is a noncompetitive NMDA receptor antagonist and produces a variety of behaviors in rats including circling. The behavioral effects of other noncompetitive NMDA receptor antagonists such as (+)-MK-801 are still being elucidated. Here, adult female rats were dosed with PCP (10 mg/kg, IP), or (+)-MK-801 (0.1 mg/kg, IP) and circling preference was recorded for 2 h before sacrifice to determine monoamine levels by HPLC/EC. Animals injected with PCP or (+)-MK-801 showed a preference to turn to the left (65% and 72%, respectively). PCP and (+)-MK-801 also produced a significant increase of 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) in whole striatum on both sides of the brain. Further dissection of the striatum into medioventral and dorsolateral regions revealed that HVA was increased bilaterally except in globus pallidus where we found significant increases in dopamine (DA), DOPAC, and HVA only on the left side after PCP and (+)-MK-801 administration. These data suggest that PCP and (+)-MK-801 produce a greater preference to turn left than right, a finding similar to that found in human psychosis. Furthermore, it is possible that this preference to turn toward the left hemispace is due to an asymmetry in dopamine function found in the globus pallidus after administration of PCP and similar drugs.

Prenatal origin of schizophrenia in a subgroup of discordant monozygotic twins.

Neuropathological, obstetrical, and epidemiological evidence increasingly suggest that some cases of adult-onset schizophrenia have prenatal or neonatal etiological roots. We evaluated the developmental histories of 23 monozygotic twin pairs discordant for schizophrenia to determine when they markedly and permanently began diverging from each other in motor skills or unusual behavior. Seven of the twins (30%) who later developed schizophrenia had become permanently different from their cotwins by age 5 years. The early divergence group differed from the others by multivariate tests (p = 0.002) for within-twin pair effects and by univariate tests for physical anomaly scores (p = 0.01), total finger ridge counts (p = 0.001), family history of psychosis (p = 0.004), and serious perinatal complications or low birth weight (p = 0.05). It is concluded that some cases of adult-onset schizophrenia are associated with prenatal events, which may include neurodevelopmental abnormalities or specific insults such as anoxia or infectious agents.

Season of birth and neurodevelopmental disorders: summer birth is associated with dyslexia.

OBJECTIVE: Increased risk for certain psychiatric disorders has been associated with season of birth. This study was undertaken to look for hypothesized season-of-birth effects for dyslexia, schizophrenia spectrum disorders, and neurological soft signs in children and adolescents. METHOD: Month of birth and the diagnostic findings in question were examined based on charts from a clinic population of 585 boys. Odds ratios and etiological fractions were calculated. RESULTS: Neurological soft signs showed a sporadic peak for June births and schizophrenia spectrum showed a peak for August and November. A smooth curve suggesting true seasonality was evident in dyslexia for births in May, June, and July. For different 5-year birth cohorts, early summer birth accounts for 24 to 71% of cases of dyslexia. CONCLUSIONS: The authors suggest that viral infection, especially influenza, during the second trimester of pregnancy is the most attractive hypothesis to explain these findings. If this hypothesis is supported, immunization in women of child-bearing age could reduce the incidence of dyslexia. Secondary prevention could also be enhanced by early identification and treatment of children who were exposed in utero.

Correlation of severity of psychiatric patients' delusions with right hemispatial inattention (left-turning behavior).

Studies associate psychotic disorders with various forms of subtle inattention to the right hemispace (left-turning behavior). The authors examined the correlation between this dopamine-related sign and severity of delusions (presumably dopaminergic symptoms) in 20 psychotic patients. Delusions were significantly correlated with severity of left-turning bias, and this neurological sign accounted for 33% of the variance in severity of delusions.

The profile of cognitive impairment in elderly dyskinetic subjects.

Cognitive performance was assessed in 107 psychiatric patients whose age exceeded 59 years and who did not carry the diagnosis of organic mental syndrome. In this sample, tardive dyskinesia (TD) was associated with greater impairment in each of the seven cognitive domains assessed. These data do not address the etiology of TD but raise questions regarding the use of antipsychotics in young patients with cognitive impairment. Insofar as TD is an expression of basal ganglia dysfunction, these data also emphasize the critical role of relatively caudal brain structures in cognition and emotional expression.

Frontostriatal disorder of cerebral metabolism in never-medicated schizophrenics.

We scanned 18 patients with schizophrenia who had never received neuroleptic medication and 20 age- and sex-matched controls by positron emission tomography with 18-F-fluorodeoxyglucose (fludeoxyglucose F 18) as a tracer of glucose metabolism. Subjects performed the Continuous Performance Test during 18-F-fluorodeoxyglucose uptake. Scan results were converted to metabolic rates, and computer algorithms were used to identify cortical regions. Previous reports of relative hypofrontality in schizophrenia were confirmed, indicating that this finding is not an artifact of previous treatment. Significantly reduced ratios of inferior and medial frontal regions to occipital cortex were found, together with diminished metabolism in the basal ganglia. This suggests the presence of a combined frontostriatal dysfunction in schizophrenia.

Psychotic symptoms and suicidal behavior in hospitalized children.

Association of psychotic symptoms with suicidal behavior was studied in 90 hospitalized prepubertal children. Children with psychotic symptoms were more likely to have threatened or attempted suicide. The association of visual hallucinations with suicidal behavior was stronger than that of auditory hallucinations or psychotic ideation. The authors speculate that psychosis in general and visual hallucinations especially may be indicators of suicide risk among children.