Familial transmission of schizophrenia in Palau: A 20-year genetic epidemiological study in three generations.

Our genetic epidemiological studies of schizophrenia and other psychotic disorders (SCZ) in the isolated population of Palau have been ongoing for 20 years. Results from the first decade showed that Palau has an elevated prevalence of SCZ and that cases cluster in extended multigenerational pedigrees interconnected via complex genetic relationships after centuries of endogamous, but not consanguineous, marriages. The aim of our second decade of research, which extended data collection into a third generation of young, high-risk (HR) Palauans, was to identify significant predictors of intergenerational transmission of illness.

Early signs and symptoms of psychosis among Palauan adolescents.

Aim: This study was designed to identify early symptoms associated with the occurrence of psychosis during adolescence.

Method: Participants were recruited in the Republic of Palau, an isolated island nation in Micronesia with a prevalence rate for schizophrenia of 1.99%.

Adoption, family relations and psychotic symptoms among Palauan adolescents who are genetically at risk for developing schizophrenia.

Purpose: This paper focuses on the role of adoption and family relations as moderators of genetic risk for psychotic disorders.

Methods: Participants included 184 adolescents in the Republic of Palau identified to be at genetic risk for schizophrenia and other psychotic disorders. Palau is an island nation in Micronesia with a lifetime prevalence of 1.

Preventive intervention for early psychosis in adolescents--the Palau Youth at Risk Project.

We have studied a total of 393 adolescents 14 to 19 years from Palau, where the lifetime morbid risk for broadly defined schizophrenia is 2.67% and cases cluster in large extended families. These Palauan adolescents included 52 offspring of a schizophrenic parent designated as "Genetically Highest Risk" or GHR+ and 61 nieces/nephews of affected sib-pairs/trios, designated "Genetically High Risk" or GHR.

Comorbid depressive symptoms in the developmental course of adolescent-onset psychosis.

AIM: Depressive symptoms are common in the early prodromal phase of schizophrenia and other psychotic disorders. The objectives of the present study were to retrospectively examine the severity of depressive symptoms and their relationship to positive symptoms over the developmental course of adolescent-onset psychosis (AO-PSY). METHODS: The subjects were 62 unmedicated adolescents with DSM-IV psychosis and 104 normal controls from a Pacific island isolate with an elevated prevalence of schizophrenia.

The Palau Early Psychosis Study: distribution of cases by level of genetic risk.

The Palau Early Psychosis Study (PEPS) was designed to examine the pathogenesis of early psychosis in a high-risk population isolate. This paper describes the characteristics of our community-based, non-help seeking sample of 404 Palauan adolescents and quantifies the presence of early psychosis by level of genetic risk. The sample included 53 offspring of a schizophrenic parent designated as "Genetically Highest Risk" (GHR+) and 68 nieces/nephews of sib-pairs/trios, designated as "Genetically High Risk" (GHR).

The Palau Early Psychosis Study: neurocognitive functioning in high-risk adolescents.

Objective: The purpose of the present study was to evaluate both the independent and joint effects of genetic risk and clinical status on neurocognitive functioning in adolescents from a population isolate with an elevated risk for schizophrenia and strong familial aggregation of cases.

Method: The subjects were 310 non-help seeking, drug-naïve adolescents 14-19 years of age from the Republic of Palau. The sample comprised 98 Genetically High Risk (GHR) adolescents, 54 of whom were symptomatic, and 212 Genetically Low Risk (GLR) adolescents, including 113 Clinically High Risk (CHR) subjects who were symptomatic and 99 normal controls who were non-symptomatic.

Recurrence risk to offspring in extended multiplex schizophrenia pedigrees from a Pacific Island isolate.

Genetic transmission plays a major role in the pathogenesis of schizophrenia. Family, twin, and adoption studies have consistently shown that risks in relatives are many times greater than the general population risk of approximately 1%. McGue, Gottesman, and Rao (1983; Am J Hum Genet 35:1161-1178) calculated risk estimates of 12.

P50 sensory gating in adolescents from a pacific island isolate with elevated risk for schizophrenia.

Background: Gating or inhibition of the P50 auditory evoked potential is a heritable neurobiological trait that has shown strong potential to serve as an endophenotype for schizophrenia. P50 sensory gating deficits have been found repeatedly in schizophrenic patients and in their unaffected first-degree relatives. P50 sensory gating has not yet been studied in high-risk (HR) offspring nor in prodromal adolescents.