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Abstract
The symptoms of adult Attention Deficit/Hyperactivity Disorder (ADHD) generally include impaired concentration; an insensitivity to social cues, being hard to get along with, and being internally restlessness. It is not surprising that these problems are likely to affect the performance of college students with ADHD. The study aims to examine whether ADHD symptoms are associated with handedness in college students in Taiwan. A total of 505 male and 645 female participants completed Annett's handedness questionnaire and the Traditional Chinese College ADHD Response Evaluation Student Response Inventory (C-CARE-SRI). Handedness was scored both categorically, mixed vs. not-mixed, and continuously, using the Hand Preference Index. The Inattention score was significantly higher for students who were mixed-handed than for those who were not, after social pressure against using the left hand to write had been adjusted for. However, the differences in Hyperactivity and Impulsivity scores were nonsignificant. In addition, the correlations between all three ADHD and Hand Preference Index factor-scores were nonsignificant. To sum up, mixed-handedness is associated with a higher Inattention score. The potential underlying mechanism relating to ADHD Inattention is discussed.
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Affiliation(s)
- Hui-Li Lin
- Department of Clinical Psychology, Fu Jen Catholic University, New Taipei City, Taiwan
| | - Hui-Chun Tsuang
- Center of General Education, Chang Jung Christian University, Tainan, Taiwan.
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Fumero A, Rodríguez M, Roa A, Peñate W. Importancia diferencial de los componentes fundamentales de la esquizotipia: un metaanálisis. REVISTA LATINOAMERICANA DE PSICOLOGIA 2017. [DOI: 10.1016/j.rlp.2016.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Tsuang HC, Chen WJ, Kuo SY, Hsiao PC. Handedness and schizotypy: The potential effect of changing the writing-hand. Psychiatry Res 2016; 242:198-203. [PMID: 27289325 DOI: 10.1016/j.psychres.2016.04.123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2015] [Revised: 03/08/2016] [Accepted: 04/18/2016] [Indexed: 12/30/2022]
Abstract
Mixed-handedness, which has been associated with schizotypy in recent studies, might exist for at least two different reasons: it is innate or it has been forced. We examined whether the association between mixed-handedness and schizotypy differs depending on its source. We enrolled 3485 college students in Taiwan. We used both the Perceptual Aberration Scale and Schizotypal Personality Questionnaire to assess schizotypy, and the Annett Hand Preference Questionnaire to assess handedness. Two ways of classifying handedness were examined: the three-way classification based on Annett's categories and mixed- vs. non-mixed-handedness based on Degree of Handedness. Both mixed-handedness groups showed higher positive schizotypy scores. Among mixed handers, those who had been required to change their writing hand from left to right had higher positive schizotypy scores. Being forced to change writing hand seemed to be related to a higher level of schizotypy. The potential effect of the social pressure against using the left hand for writing is discussed.
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Affiliation(s)
- Hui-Chun Tsuang
- Center of General Education, School of Liberal Arts Education, Chang Jung Christian University, No. 396, Sec. 1, Changrong Road, Gueiren District, Tainan 71101, Taiwan.
| | - Wei J Chen
- Institute of Epidemiology and Preventive Medicine, College of Public Health, National Taiwan University, Taipei, Taiwan; Genetic Epidemiology Core Laboratory, Center of Genomic Medicine, National Taiwan University, Taipei, Taiwan
| | - Shu-Yu Kuo
- School of Nursing, Taipei Medical University, Taipei, Taiwan
| | - Po-Chang Hsiao
- Genetic Epidemiology Core Laboratory, Center of Genomic Medicine, National Taiwan University, Taipei, Taiwan
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Marcinowski EC, Campbell JM, Faldowski RA, Michel GF. Do hand preferences predict stacking skill during infancy? Dev Psychobiol 2016; 58:958-967. [PMID: 27163298 DOI: 10.1002/dev.21426] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 04/24/2016] [Indexed: 11/10/2022]
Abstract
The cascade theory of handedness suggests that hand preferences develop from a history of cascading and sequentially developing manual asymmetries for a variety of actions. Infants who consistently use their preferred hand for a variety of actions likely would gain proficiency using that preferred hand and, consequently, perform more proficiently on other challenging manual tasks. One such task is object stacking, which has been linked with a number of cognitive abilities. If infant hand preference facilitates the development of stacking skill, then this could provide a link by which early hand preference might affect the development of cognition. From a sample of 380 infants assessed for an acquisition hand preference across 6-14 months, 131 infants were assessed for stacking skill from 10 to 14 months at monthly visits. Four unique handedness sub-groups were identified from the 380-infant sample: left, trending right, stable right, or no hand preference. Each of the four hand preference groups exhibited different trajectories in the development of their stacking skills. Left- and stable right-handers stacked more items than infants with no preference by 14 months, whereas infants with a trending right preference did not. The proportion of preferred hand use (right and left) from 6 to 9 months also predicted an earlier initial onset of stacking skill, whereas the proportion of only right hand use did not. Thus, the development of a hand preference predicts an earlier emergence of stacking skill and may have implications for other domains of infant cognitive development.
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Affiliation(s)
- Emily C Marcinowski
- Department of Psychology, The University of North Carolina, Greensboro, North Carolina
| | - Julie M Campbell
- Department of Psychology, The University of North Carolina, Greensboro, North Carolina
| | - Richard A Faldowski
- Department of Allied Health Sciences, The University of North Carolina, Chapel Hill, North Carolina
| | - George F Michel
- Department of Psychology, The University of North Carolina, Greensboro, North Carolina
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Dean DJ, Orr JM, Newberry RE, Mittal VA. Motor behavior reflects reduced hemispheric asymmetry in the psychosis risk period. Schizophr Res 2016; 170:137-42. [PMID: 26492987 PMCID: PMC4707112 DOI: 10.1016/j.schres.2015.10.017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Revised: 10/06/2015] [Accepted: 10/09/2015] [Indexed: 12/29/2022]
Abstract
BACKGROUND A body of work focusing on brain connectivity, language dominance, and motor laterality research suggests that reduced hemispheric asymmetry is a core feature in schizophrenia. However, there is little consensus about whether reduced dominance is present in those at ultrahigh risk (UHR) for psychosis. METHODS A total of 94 demonstrated right-handed neuroleptic free participants (38 UHR and 56 matched healthy controls) were assessed with structured clinical interviews and completed an innovative handwriting task using a digital tablet computer. A laterality quotient (LQ) was calculated using kinematic variables from the participant's left and right hands. A subset of the sample (26 UHR and 29 controls) returned after 12-months to complete clinical interviews in order to examine relationships between handwriting laterality and progression of psychosis risk symptoms. RESULTS The UHR group showed decreased dextrality compared to healthy controls. At the 12-month follow-up, decreased dextrality accounted for 8% of the variance in worsened positive symptoms within the UHR group. CONCLUSION The current results suggest that disrupted cerebral dominance is also present in the ultrahigh risk period and that decreased dextrality may serve as a novel biomarker for the progression of psychosis risk.
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Affiliation(s)
- Derek J Dean
- University of Colorado Boulder, Department of Psychology and Neuroscience, United States; University of Colorado Boulder, Center for Neuroscience, United States.
| | - Joseph M Orr
- Texas A&M University, Department of Psychology, United States
| | - Raeana E Newberry
- University of Colorado Boulder, Department of Psychology and Neuroscience, United States
| | - Vijay A Mittal
- Northwestern University, Department of Psychology, United States
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Dinsdale NL, Hurd PL, Wakabayashi A, Elliot M, Crespi BJ. How are autism and schizotypy related? Evidence from a non-clinical population. PLoS One 2013; 8:e63316. [PMID: 23691021 PMCID: PMC3655150 DOI: 10.1371/journal.pone.0063316] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 03/29/2013] [Indexed: 12/21/2022] Open
Abstract
Both autism spectrum conditions (ASCs) and schizophrenia spectrum conditions (SSCs) involve altered or impaired social and communicative functioning, but whether these shared features indicate overlapping or different etiological factors is unknown. We outline three hypotheses (overlapping, independent, and diametric) for the possible relationship between ASCs and SSCs, and compare their predictions for the expected relationships between autistic and schizotypal phenotypes using the Autism Spectrum Quotient and the Schizotypal Personality Questionnaire-Brief Revised from a large non-clinical sample of undergraduate students. Consistent with previous research, autistic features were positively associated with several schizotypal features, with the most overlap occurring between interpersonal schizotypy and autistic social and communication phenotypes. The first component of a principal components analysis (PCA) of subscale scores reflected these positive correlations, and suggested the presence of an axis (PC1) representing general social interest and aptitude. By contrast, the second principal component (PC2) exhibited a pattern of positive and negative loadings indicative of an axis from autism to positive schizotypy, such that positive schizotypal features loaded in the opposite direction to core autistic features. These overall PCA patterns were replicated in a second data set from a Japanese population. To evaluate the validity of our interpretation of the PCA results, we measured handedness and mental rotation ability, as these are established correlates of SSCs and ASCs, respectively. PC2 scores were significantly associated with hand preference, such that increasingly 'schizotypal' scores predicted reduced strength of handedness, which is consistent with previous research. PC1 scores were positively related to performance on the mental rotation task, suggesting trade-offs between social skills and visual-spatial ability. These results provide novel evidence for an autism-positive schizotypy axis, and highlight the importance of recognizing that psychological variation involving reduced social interest and functioning may have diverse causes.
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Tsuang HC, Chen WJ, Kuo SY, Hsiao PC. The cross-cultural nature of the relationship between schizotypy and mixed-handedness. Laterality 2012; 18:476-90. [PMID: 23072536 DOI: 10.1080/1357650x.2012.720985] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Positive schizotypy is associated with non-right-handedness, which includes left- and mixed-handedness. However, because the underlying mechanisms might be different, it is important to examine whether both left- and mixed-handedness are associated with a high incidence of schizotypy. During 2009-2010, we used both the Perceptual Aberration Scale and Schizotypal Personality Questionnaire to assess 1315 undergraduate students in Taiwan for schizotypy and the Annett handedness questionnaire to assess handedness. Among the three-way classifications based on Annett's grouping, the fully left-handed group appeared to have the lowest score of positive schizotypy; next was the fully right-handed group and then the mixed-handed. Among the three-way classifications driven from cluster analysis, mixed-handers showed highest score of positive schizotypy. When handedness was treated continuously, both direction (e.g., Hand Preference Index) and consistency (e.g., Either hand use score) indicators were significantly correlated with schizotypy. The results of regression analyses showed that the quadratic handedness measure were negatively associated with schizotypy. The results remained similar after correcting for social pressure on left-handedness. In conclusion, the relationship between schizotypy and mixed-handedness appears to be cross-cultural. The dichotomous classification of handedness, right- vs. non-right-handedness, appears to be insufficient. Additional studies on the distinct mechanisms of mixed- and left-handedness are warranted.
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Kelley MP. Lateral preference and schizotypy revisited: Comparison of handedness measurement and classification methods. Laterality 2012; 17:150-68. [DOI: 10.1080/1357650x.2010.546798] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/09/2023]
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Sontam V, Christman SD. Semantic organisation and handedness: mixed-handedness is associated with more diffuse activation of ambiguous word associates. Laterality 2011; 17:38-50. [PMID: 21598173 DOI: 10.1080/1357650x.2010.529450] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Research indicates that there are individual differences in the flexibility and ease with which one retrieves and uses concepts stored in memory. Based on prior research suggesting that mixed-handedness is associated with greater cognitive flexibility, it was hypothesised that mixed-handers have access to a relatively diffuse associative network, where link strengths for closely related and distantly related concepts are not as disparate as in the case of strong-handers. This idea was explored using ambiguous words for stimuli, as ambiguous words are known to have both strong (concepts related via dominant meaning) and weak associates (concepts related via subordinate meaning). Consistent with the prediction, mixed-handers showed equal ease in accessing both strongly and weakly related concepts. In Experiment 1 mixed-handers exhibited equivalent priming for dominant and subordinate associates, while strong-handers exhibited priming for dominant associates only. In Experiment 2 ratings of strength of association for dominant versus subordinate associates were examined. Mixed-handedness was associated with lesser disparity of dominant and subordinate association ratings.
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Chapman HL, Grimshaw GM, Nicholls MER. Going beyond students: an association between mixed-hand preference and schizotypy subscales in a general population. Psychiatry Res 2011; 187:89-93. [PMID: 21176970 DOI: 10.1016/j.psychres.2010.11.019] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/28/2010] [Revised: 11/12/2010] [Accepted: 11/12/2010] [Indexed: 10/18/2022]
Abstract
Research on the sub-clinical condition of schizotypy suggests that it is associated with mixed handedness. To date, however, this research has focussed on undergraduate populations. If the association between schizotypy and mixed-handedness is the result of an underlying neurological trait, it is important to demonstrate that the effect extends to the general population. With this in mind, 699 participants were drawn from a wide community sample. Schizotypy was measured using the Psychosis Proneness Questionnaire and handedness was assessed using the Annett inventory. To avoid the sometimes arbitrary definitions of left-, right- and mixed-handed, regression analyses were used to explore the data. There was no evidence of a difference in schizotypy between individuals with a left- or right-hand preference. People with a mixed-hand preference, however, had higher scores on PER-MAG (Perceptual Aberration and Magical Ideation) and HYP-IMP (Hypomania and Impulsive Non-Conformity) scales (positive traits). No effect was observed for the SAN (Social Anhedonia) and PAN (Physical Anhedonia) scales (negative traits). The nature of the association between schizotypy and handedness observed in the current study is similar to that reported for student populations. The possibility that the association is related to response biases or a biological mechanism is discussed.
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Affiliation(s)
- Heidi L Chapman
- School of Psychology, The University of Birmingham, Birmingham, UK.
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Tsuang HC, Liu CM, Hwang TJ, Hsieh MH, Faraone SV, Tsuang MT, Hwu HG, Chen WJ. Handedness and schizotypy in non-psychotic relatives of patients with schizophrenia. Laterality 2011; 16:690-706. [PMID: 21308606 DOI: 10.1080/1357650x.2010.511646] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Existing studies have found the relationship between handedness and schizotypy to be inconsistent, and had limited generalisability since only highly homogeneous groups have been investigated. This study aimed to examine the relation between handedness and the four schizotypal factors identified from a previous confirmatory factor analysis in a population of high familial loading for schizophrenia. Study participants consisted of non-psychotic first-degree relatives (850 parents and 334 siblings) of sib-pairs who were co-affected with schizophrenia. All participants were interviewed with the Diagnostic Interview for Genetic Studies, which contains a section of the modified Structured Interview for Schizotypy, and the Annett handedness questionnaire. Both categorical and continuous indicators for handedness were examined. Non-right-handed siblings of schizophrenia patients displayed more positive schizotypal features than their right-handed counterparts when the two-way Annett's handedness classification was adopted. No association was found when handedness was treated as continuous. The relationship between handedness and schizotypy was insignificant for parents probably due to the strong social pressure against left-handedness. We concluded that categorical non-right-handedness was associated with positive schizotypy in non-psychotic siblings of schizophrenia patients. The results indicate that an atypical cerebral lateralisation underlying non-right-handedness may be also a contributing factor to positive schizotypy.
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van der Hoorn A, Oldehinkel AJ, Ormel J, Bruggeman R, Uiterwaal CSPM, Burger H. Non-right-handedness and mental health problems among adolescents from the general population: The Trails Study. Laterality 2010; 15:304-16. [DOI: 10.1080/13576500902746839] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
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Abstract
Previous single studies have found inconsistent results on sex differences in positive schizotypy, women scoring mainly higher than men, whereas in negative schizotypy studies have often found that men score higher than women. However, information on the overall effect is unknown. In this study, meta-analytic methods were used to estimate sex differences in Wisconsin Schizotypy Scales developed to measure schizotypal traits and psychosis proneness. We also studied the effect of the sample characteristics on possible differences. Studies on healthy populations were extensively collected; the required minimum sample size was 50. According to the results, men scored higher on the scales of negative schizotypy, ie, in the Physical Anhedonia Scale (n = 23 studies, effect size, Cohen d = 0.59, z test P < .001) and Social Anhedonia Scale (n = 14, d = 0.44, P < .001). Differences were virtually nonexistent in the measurements of the positive schizotypy, ie, the Magical Ideation Scale (n = 29, d = -0.01, P = .74) and Perceptual Aberration Scale (n = 22, d = -0.08, P = .05). The sex difference was larger in studies with nonstudent and older samples on the Perceptual Aberration Scale (d = -0.19 vs d = -0.03, P < .05). This study was the first one to pool studies on sex differences in these scales. The gender differences in social anhedonia both in nonclinical samples and in schizophrenia may relate to a broader aspect of social and interpersonal deficits. The results should be taken into account in studies using these instruments.
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Affiliation(s)
| | - Erika Jääskeläinen
- Department of Psychiatry, Oulu University and Oulu University Hospital, Oulu, Finland
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Neurological soft signs and schizotypal dimensions in unaffected siblings of patients with schizophrenia. Psychiatry Res 2010; 175:22-6. [PMID: 19959242 DOI: 10.1016/j.psychres.2008.10.013] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2008] [Revised: 10/13/2008] [Accepted: 10/23/2008] [Indexed: 11/21/2022]
Abstract
The objectives were to determine the neurological soft signs (NSS) scores in unaffected siblings of patients with schizophrenia compared with healthy controls and to examine their relationships with schizotypal dimensions. Participants comprised 31 unaffected siblings of patients with schizophrenia and 60 healthy controls matched according to age, gender and school level who were assessed by the Schizotypal Personality Questionnaire (SPQ) and the Krebs et al. NSS Scale. Higher NSS total scores and sub-scores were found in the unaffected siblings compared with the controls. The SPQ total score was significantly higher in unaffected siblings compared with control subjects. The NSS total score was positively correlated with the SPQ total score and the SPQ disorganization sub-score in unaffected siblings of patients with schizophrenia. Additionally, in unaffected siblings, motor coordination and integration abnormalities were positively correlated with the SPQ total score and the cognitive-perceptual sub-score. Motor integration abnormalities were also correlated with the SPQ disorganization sub-score. These results reveal that NSS, especially motor signs, are associated with some schizotypal dimensions in siblings of patients with schizophrenia, suggesting the value of using both assessments to study high risk populations.
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Bryson FM, Grimshaw GM, Wilson MS. The role of intellectual openness in the relationship between hand preference and positive schizotypy. Laterality 2009; 14:441-56. [DOI: 10.1080/13576500802349684] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Hand-preference and population schizotypy: a meta-analysis. Schizophr Res 2009; 108:25-32. [PMID: 19106036 DOI: 10.1016/j.schres.2008.11.010] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2008] [Revised: 10/27/2008] [Accepted: 11/08/2008] [Indexed: 12/29/2022]
Abstract
Language functions in schizophrenia patients are represented more bilateral, i.e. less lateralized than in healthy subjects. This decreased lateralization is also observed in individuals at increased risk for schizophrenia. Language lateralization is related to handedness; in that left- and mixed-handed individuals more frequently have decreased lateralization in comparison to right-handed subjects. Population schizotypy can be considered part of the schizophrenia spectrum disorders. In line with this, population schizotypy has repeatedly, though inconsistently, been associated with left-handedness. In order to define the exact association between handedness and schizotypy, we performed meta-analyses on the available literature. We found that non-right-handed subjects, but not strong left-handers, had higher scores on schizotypy questionnaires than right-handed subjects. Mixed-handers showed a trend towards higher schizotypy in comparison to strong left-handers. It is argued that the higher schizotypy in non-right-handed individuals reflects the higher incidence of bilateral language lateralization in this group. Bilateral language organisation may underlie loosening of association, possibly leading to higher schizotypy scores.
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Grimshaw GM, Yelle SK, Schoger J, Bright KS. Magical ideation is related to questionnaire but not behavioural measures of handedness. Laterality 2008; 13:22-33. [PMID: 17891681 DOI: 10.1080/13576500701508539] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Magical ideation has repeatedly been shown to be related to handedness, with mixed-handers exhibiting higher levels of magical thinking. However, most previous research has assessed hand preference with a questionnaire measure, leaving open the possibility that the correlation reflects some aspect of questionnaire-taking behaviour and not an underlying neuropsychological relationship. The present study addressed this issue by administering the Magical Ideation Scale (Eckblad & Chapman, 1983), the Waterloo Handedness Questionnaire-Revised (Elias, Bryden, & Bulman-Fleming, 1998), and a manual dot-filling task (Tapley & Bryden, 1985) as a behavioural measure of handedness to an undergraduate student sample. The expected relationship between magical ideation and handedness as assessed by the questionnaire was observed. However, magical ideation was not related to the behavioural measure of handedness. Results cast doubt on a neuropsychological interpretation of the relationship between handedness and magical ideation in sub-clinical populations.
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Affiliation(s)
- Gina M Grimshaw
- School of Psychology, Victoria University of Wellington, Wellington, New Zealand.
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Preti A, Sardu C, Piga A. Mixed-handedness is associated with the reporting of psychotic-like beliefs in a non-clinical Italian sample. Schizophr Res 2007; 92:15-23. [PMID: 17360160 DOI: 10.1016/j.schres.2007.01.028] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2006] [Revised: 01/30/2007] [Accepted: 01/31/2007] [Indexed: 12/21/2022]
Abstract
Atypical handedness has been repeatedly reported in schizophrenia, with quantitative review of evidence showing an increase of non-right-handedness in patients diagnosed with schizophrenia. Mixed-handedness is also higher among non-clinical people scoring high on questionnaires aimed at measuring psychosis-proneness. However, the greatest part of information on non-clinical samples came from samples collected in North America or in the UK: differences by countries in the socio-cultural pressure to use the right hand could influence the results. In this study 604 Italian non-clinical participants (248 males, 41.1%; 356 females, 58.9%; mean age=34.5+/-11.9) completed the Annett Hand Preference Questionnaire (HPQ), the General Health Questionnaire (GHQ), and the Peters et al. Delusions Inventory (PDI). In the sample, 527 subjects (87.3%) were classified on the HPQ as right-handed, 53 (8.8%) were classified as mixed-handed, and 24 (4.0%) were classified as left-handed. Mixed-handed scored statistically higher on the PDI than the right-handed and left-handed, but right-handed and left-handed did not differ from each other on a statistical ground. The difference by handedness was specific for PDI, since scores on the GHQ-12 did not differ by handedness group. The links between mixed-handedness and psychosis-proneness in non-clinical samples are a reliable finding, deserving further investigation as a model for the risk of schizophrenia.
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Affiliation(s)
- Antonio Preti
- Department of Psychology, University of Cagliari, via Is Mirrionis 1, 09123 Cagliari, Italy.
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