Cognitive Subtypes of Schizophrenia Characterized by Differential Brain Volumetric Reductions and Cognitive Decline.
OBJECTIVE
Cognitively distinct subgroups of schizophrenia have been defined based on premorbid and current IQ, but little is known about the neuroanatomical differences among these cognitive subgroups.


OBJECTIVE
To confirm previous findings related to IQ-based subgroups of patients with schizophrenia in an independent sample and extend those findings to determine the extent to which brain volumetric differences correspond to the IQ-based subgroups.


METHODS
A total of 183 participants were assessed at the outpatient settings of Neuroscience Research Australia and Lyell McEwin Hospital from September 22, 2009, to August 1, 2012. Patients were classified using cluster analysis on the basis of current and premorbid IQ differences. Regional magnetic resonance imaging (MRI) brain volumes were compared among the IQ-based subgroups using analysis of covariance with intracranial volume and age as covariates.


METHODS
Wechsler Adult Intelligence Scale, third edition, scores; Wechsler Test of Adult Reading scores; Positive and Negative Syndrome Scale scores; and MRI brain volumes.


RESULTS
Ninety-six outpatients (mean [SD] age, 35.7 [8.4] years; age range, 18-51 years; 59 men) with schizophrenia or schizoaffective disorder and 87 healthy controls (mean [SD] age, 31.9 [8.4] years; age range, 20-50 years; 46 men) were studied. Sixty-two patients and 67 healthy controls underwent structural MRI of the brain. Cluster analyses revealed 25 putatively preserved patients (26%), 33 moderately deteriorated patients (34%), 27 severely deteriorated patients (28%), and 11 compromised patients (12%). Negative symptom scores were significantly worse in the severely deteriorated group relative to the putatively preserved group (F2,82 = 13.8, P < .001, effect size [ES] = 1.40). Patient subgroups analyzed revealed significantly reduced inferior parietal volume relative to controls (F3,113 = 9.7, P < .001, ES = 0.85-1.24). The severely deteriorated group had significantly reduced total hippocampal (mean [SEM], 8309.6 [175.0] vs 9024.0 [145.5]; P = .01), lingual gyrus (mean [SEM], 11 996.0 [531.5] vs 13 838.1 [441.9]; P = .05), and superior temporal sulcus (mean [SEM], 4697.8 [192.0] vs 5446.0 [159.6]; P = .05) gray matter volumes relative to the putatively preserved group (ES = 0.91-1.10).


CONCLUSIONS
Using an independent sample, we obtained proportions in each IQ-based subgroup that were similar to our previous work. Inferior parietal volume reduction was characteristic of schizophrenia relative to controls, and the severely deteriorated IQ group had widespread volumetric reductions. Classifying cognitive heterogeneity in schizophrenia provides a platform to better characterize the neurobiological underpinnings of the illness and its treatment.
Neuroscience Research Australia, Randwick, New South Wales, Australia.
Danielle
D
Weinberg
Neuroscience Research Australia, Randwick, New South Wales, Australia2School of Psychiatry, University of New South Wales, Kensington, New South Wales, Australia3Schizophrenia Research Institute, Darlinghurst, New South Wales, Australia.
Rhoshel
R
Lenroot
Neuroscience Research Australia, Randwick, New South Wales, Australia.
Isabella
I
Jacomb
Neuroscience Research Australia, Randwick, New South Wales, Australia2School of Psychiatry, University of New South Wales, Kensington, New South Wales, Australia3Schizophrenia Research Institute, Darlinghurst, New South Wales, Australia.
Katherine
K
Allen
Neuroscience Research Australia, Randwick, New South Wales, Australia2School of Psychiatry, University of New South Wales, Kensington, New South Wales, Australia.
Jason
J
Bruggemann
Neuroscience Research Australia, Randwick, New South Wales, Australia2School of Psychiatry, University of New South Wales, Kensington, New South Wales, Australia.
Ruth
R
Wells
Discipline of Psychiatry, University of Adelaide, Adelaide, South Australia, Australia5School of Psychology, Flinders University, Adelaide, South Australia, Australia.
Ryan
R
Balzan
Discipline of Psychiatry, University of Adelaide, Adelaide, South Australia, Australia6Adult Mental Health Services, Northern Adelaide Local Health Network, Adelaide, South Australia, Australia.
Dennis
D
Liu
Discipline of Psychiatry, University of Adelaide, Adelaide, South Australia, Australia6Adult Mental Health Services, Northern Adelaide Local Health Network, Adelaide, South Australia, Australia.
Cherrie
C
Galletly
Neuroscience Research Australia, Randwick, New South Wales, Australia7School of Medicine, University of Queensland, Brisbane, Queensland, Australia.
Stanley V
SV
Catts
Neuroscience Research Australia, Randwick, New South Wales, Australia2School of Psychiatry, University of New South Wales, Kensington, New South Wales, Australia3Schizophrenia Research Institute, Darlinghurst, New South Wales, Australia.
Cynthia Shannon
CS
Weickert
Neuroscience Research Australia, Randwick, New South Wales, Australia2School of Psychiatry, University of New South Wales, Kensington, New South Wales, Australia3Schizophrenia Research Institute, Darlinghurst, New South Wales, Australia.
Thomas W
TW
Weickert
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000704:Analysis of Variance; D001284:Atrophy; D001921:Brain / Q000000981:diagnostic imaging* / Q000473:pathology; D003072:Cognition Disorders / Q000000981:diagnostic imaging* / Q000523:psychology*; D005260:Female; D006801:Humans; D007090:Image Interpretation, Computer-Assisted; D007360:Intelligence / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009929:Organ Size / Q000502:physiology; D011569:Psychiatric Status Rating Scales; D011618:Psychotic Disorders / Q000000981:diagnostic imaging* / Q000523:psychology*; D012559:Schizophrenia / Q000000981:diagnostic imaging*; D012565:Schizophrenic Psychology; D014888:Wechsler Scales; D055815:Young Adult