The Neuropsychology of Schizophrenia Circa 2009

Abstract

Keywords Neuropsychology.Cognitiveneuroscience.Genetics.Informatics.Neuroimaging.Phenomics.SchizophreniaThe last 30 years have been marked by the emergence oftransformative technologies for the study of brain structure-function relations, and these have been deployed vigorouslyto help unravel the mysterious causes for, and treatmentsfor the schizophrenia syndrome. Despite the progress, theultimate goal—to identify a “smoking gun,” in the form ofa cognitive, a functional anatomical or a genetic signatureresponsible for the brain pathology underlying schizophre-nia—remains elusive. This collection of articles from globalleaders in neuropsychological research on schizophreniamakes poignant how much our thinking has changed overthe last three decades, but also that we still have morequestions than answers about the fundamental neurobio-logical underpinnings of schizophrenia.To put the progress in perspective, we may recall theconclusions of Heaton et al. (1978), following theirincisive review of neuropsychological studies of psychiatricdisorders:“The finding that chronic or process schizophrenicslook like organics on neuropsychological tests mightbe considered surprising … One fairly popularexplanation … is that … motivational deficienciesand thought disorders are responsible … the implica-tion is that these deficits are functional in nature. Thisexplanation cannot be ruled out on the basis ofcurrently available evidence, but it can be questioned”(page 156); and “[it is likely that] chronic schizo-phrenics will appear organic on neuropsychologicaltesting because a significant proportion of them areorganic” (page 157).These prescient (and diplomatic) statements signal whatwas then a prevalent dualistic perspective, the echoes ofwhich are now only faint. For example, one may note thatthe term “organic” was effectively scrubbed from theDSM-IV, contrasting to its conspicuous presence in theDSM-III. If the 21st century is one day seen as markingthe death of dualism in psychiatric taxonomies, this maybe considered a victory for neuropsychology, neuroimag-ing (which provided compelling evidence of structuralbrain anomalies (Johnstone et al. 1976)), and genetics(confirming heritability of ~80% for the schizophreniasyndrome). Whatever the driving forces, it is now com-monplace to seek biological explanations for both thecauses and treatments of schizophrenia, and this reflects asea change in thinking for which neuropsychology canclaim significant credit.The reviews in this issue offer snapshots from multipleperspectives embraced in 21st century research on theneuropsychology of schizophrenia. These papers show thatneuropsychology has become central to the study of boththe causes and treatments of schizophrenia.& Palmer, Dawes, and Heaton offer a broad historicalview, highlighting the role neuropsychological research