Does originating from a genetic isolate affect the level of cognitive impairments in schizophrenia families?
Earlier studies have detected differences in the prevalence, symptomatology and genetic risk variants of schizophrenia between a north-eastern Finnish genetic isolate and the rest of Finland. This study compared a population-based isolate sample (145 persons with schizophrenia, 304 first-degree relatives and 32 controls) with a rest of Finland sample (73 persons with schizophrenia, 100 first-degree relatives and 80 controls) in cognitive functioning. Persons from the isolate outperformed persons in the rest of Finland sample in verbal learning, verbal ability and cognitive flexibility in the schizophrenia groups and in verbal learning, speeded processing and attentional control in the relatives groups. The differences between the subsamples remained significant after taking into account an intragenic Reelin STR allele, previously associated with cognitive impairments and almost absent from the isolate, in addition to disorder characteristics and familial loading. In control groups, we observed no differences between the isolate and the rest of Finland. In conclusion, cognitive impairments were milder in schizophrenia patients and their first-degree relatives within than outside the isolate. An absence of differences between the control samples suggests that the differences in schizophrenia families may relate to genetic background, possibly to partly distinct variants affecting the liability inside and outside the isolate.
Department of Mental Health and Substance Abuse Services, National Institute for Health and Welfare, PO Box 30, 00271 Helsinki, Finland. minna.torniainen@thl.fi
Minna
M
Torniainen
Juho
J
Wedenoja
Teppo
T
Varilo
Timo
T
Partonen
Jaana
J
Suokas
Laura
L
Häkkinen
Jouko
J
Lönnqvist
Jaana
J
Suvisaari
Annamari
A
Tuulio-Henriksson
D000328:Adult; D000368:Aged; D000483:Alleles; D016022:Case-Control Studies; D015816:Cell Adhesion Molecules, Neuronal / Q000235:genetics*; D003072:Cognition Disorders / Q000150:complications / Q000235:genetics* / Q000523:psychology; D016326:Extracellular Matrix Proteins / Q000235:genetics*; D005190:Family / Q000523:psychology*; D005192:Family Health; D005260:Female; D005387:Finland; D020022:Genetic Predisposition to Disease / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000235:genetics*; D009483:Neuropsychological Tests; D000091042:Reelin Protein; D012559:Schizophrenia / Q000150:complications / Q000235:genetics*; D012565:Schizophrenic Psychology; D012697:Serine Endopeptidases / Q000235:genetics*
D015816:Cell Adhesion Molecules, Neuronal; D016326:Extracellular Matrix Proteins; D009419:Nerve Tissue Proteins; D000091042:Reelin Protein; C000717127:RELN protein, human; D012697:Serine Endopeptidases