Are you L D Bradford?

Claim your profile

Publications (3)19.19 Total impact

  • Article: Persistent infection with neurotropic herpes viruses and cognitive impairment.
    [show abstract] [hide abstract]
    ABSTRACT: BACKGROUND: Herpes virus infections can cause cognitive impairment during and after acute encephalitis. Although chronic, latent/persistent infection is considered to be relatively benign, some studies have documented cognitive impairment in exposed persons that is untraceable to encephalitis. These studies were conducted among schizophrenia (SZ) patients or older community dwellers, among whom it is difficult to control for the effects of co-morbid illness and medications. To determine whether the associations can be generalized to other groups, we examined a large sample of younger control individuals, SZ patients and their non-psychotic relatives (n=1852). Method Using multivariate models, cognitive performance was evaluated in relation to exposures to herpes simplex virus type 1 (HSV-1), herpes simplex virus type 2 (HSV-2) and cytomegalovirus (CMV), controlling for familial and diagnostic status and sociodemographic variables, including occupation and educational status. Composite cognitive measures were derived from nine cognitive domains using principal components of heritability (PCH). Exposure was indexed by antibodies to viral antigens. RESULTS: PCH1, the most heritable component of cognitive performance, declines with exposure to CMV or HSV-1 regardless of case/relative/control group status (p = 1.09 × 10-5 and 0.01 respectively), with stronger association with exposure to multiple herpes viruses (β = -0.25, p = 7.28 × 10-10). There were no significant interactions between exposure and group status. CONCLUSIONS: Latent/persistent herpes virus infections can be associated with cognitive impairments regardless of other health status.
    Psychological Medicine 09/2012; · 6.16 Impact Factor
  • Article: Heritability of functioning in families with schizophrenia in relation to neurocognition.
    [show abstract] [hide abstract]
    ABSTRACT: The role of daily functioning is an integral part of the schizophrenia (SZ) phenotype and deficits in this trait appear to be present in both affected persons and some unaffected relatives; hence we have examined its heritability in our cohort of African American schizophrenia families. There is now ample evidence that deficits in cognitive function can impact family members who are not themselves diagnosed with SZ; there is some, but less evidence that role function behaves likewise. We evaluate whether role function tends to "run in families" who were ascertained because they contain an African American proband diagnosed with SZ. We analyzed heritability for selected traits related to daily function, employment, living situation, marital status, and Global Assessment Scale (GAS) score; modeling age, gender, along with neurocognition and diagnosis as covariates in a family based African-American sample (N=2488 individuals including 979 probands). Measures of role function were heritable in models including neurocognitive domains and factor analytically derived neurocognitive summary scores and demographics as covariates; the most heritable estimate was obtained from the current GAS scores (h2=0.72). Neurocognition was not a significant contributor to heritability of role function. Commonly assessed demographic and clinical indicators of functioning are heritable with a global rating of functioning being the most heritable. Measures of neurocognition had little impact on heritability of functioning overall. The family covariance for functioning, reflected in its heritability, supports the concept that interventions at the family level, such as evidenced-based family psychoeducation may be beneficial in schizophrenia.
    Biological Psychiatry 05/2012; 139(1-3):105-9. · 8.28 Impact Factor
  • Article: Linkage analysis of schizophrenia in African-American families.
    [show abstract] [hide abstract]
    ABSTRACT: While many studies have sought a window into the genetics of schizophrenia, few have focused on African-American families. An exception is the Project among African-Americans to Explore Risks for Schizophrenia (PAARTNERS), which seeks to identify novel and known risk variation for schizophrenia by genetic analyses of African-American families. We report a linkage study of diagnostic status in 217 African-American families using the Illumina Linkage Panel. Due to assumed incomplete and time-dependent penetrance, we performed linkage analysis using two different treatments of diagnosis: (1) treating both affected and unaffected individuals as informative for linkage (using the program SIBPAL) and (2) treating only affected individuals as informative (using the program MERLIN). We also explore three definitions of affected status: narrowly defined schizophrenia; one broadened to include schizoaffective disorder; and another including all diagnoses indicating psychosis. Several regions show a decrease in the evidence for linkage as the definition broadens 8q22.1 (rs911, 99.26 cM; SIBPAL p-value [p] goes from 0.006 to 0.02), 16q24.3 (rs1006547, 130.48 cM; p from 0.00095 to 0.0085), and 20q13.2 (rs1022689, 81.73 cM; p from 0.00015 to 0.032). One region shows a substantial increase in evidence for linkage, 11p15.2 (rs722317, 24.27 cM; p from 0.0022 to 0.0000003); MERLIN results support the significance of the SIBPAL results (p=0.00001). Our linkage results overlap two broad, previously-reported linkage regions: 8p23.3-p12 found in studies sampling largely families of European ancestry; and 11p11.2-q22.3 reported by a study of African-American families. These results should prove quite useful for uncovering loci affecting risk for schizophrenia.
    Schizophrenia Research 05/2009; 109(1-3):70-9. · 4.75 Impact Factor