'Schizoaffective Disorder' Dead
or
Ming
Tsuang, MD,
T.
Alive? PhD
\s=b\ Schizoaffective disorder, traditionally classified under schizophrenia, recently tends to be subsumed under affective disorder. This article reports a study of 35 sib pairs, where each six was independently diagnosed as having schizophrenia (SC), affective disorder (AD), or schizoaffective disorder (SA). The observed numbers of same-diagnosis pairs (ADAD, SASA, SCSC) were compared with the numbers expected if the three disorders are genetically independent. The results showed a significant deficiency only in the observed number of SASA pairs, which suggests that schizophrenia and affective disorder are genetically distinct whereas schizoaffective disorder is not.
To test whether schizoaffective disorder is a variant of affective disorder or schizophrenia, the observed number of ADSA and SASC pairs were compared against the expected numbers. No significant differences were found, which suggests that schizoaffective disorder is genetically heterogeneous, with at least two subtypes, one a variant of affective disorder, the other a variant of schizophrenia. (Arch Gen Psychiatry 36:633-634, 1979)
disorder has
been classified there is a strong to subsume schizoaffective disorder under affective disorder.-" On the other hand, although the available data do not convincingly support the concept that schizoaffective disorder is independent from schizophrenia or affective disorder, families who include many members affected with mixtures of schizophrenic and affective features have been reported. These reports suggest that schizoaffective disorder may be a genetically independent
traditionally Schi z oaffecti v e schizophrenia.1 However, tendency recently under
entity."·1-
Since the treatment of schizoaffective disorder depends greatly on how one views the nature of schizoaffective disorder, more research should be carried out to investigate what schizoaffective disorder really is. The present article Accepted
for publication Feb 12, 1979. From the Department of Psychiatry, University of Iowa College of Medicine, Iowa City. Reprint requests to the Department of Psychiatry, University of Iowa College of Medicine, 500 Newton Rd, Iowa City, IA 52242 (Dr Tsuang).
used data on sib pairs to answer two questions: (1) Is schizoaffective disorder genetically independent? (2) Is schizoaffective disorder a variant of affective disorder or
schizophrenia? SUBJECTS AND METHODS Case histories of 71 pairs of sibs who were both hospitalized for mental disorders'3 were studied. The conditions of all of these patients were diagnosed without knowledge of their sib relation¬ ships by Eliot Slater, MD, formerly director of the MRC Psychiat¬ ric Genetics Research Unit, Maudsley Hospital, University of London. In 35 of these pairs, the mental disorders seen were schizophrenia or affective disorder in both sibs, or schizophrenia in one and affective disorder in the other. Case histories of these 70 patients were given to George Winokur, MD, head of the Depart¬ ment of Psychiatry, University of Iowa, Iowa City, for rediagnosis of their conditions into three groups: (1) schizophrenia (SC), (2) affective disorder (AD), or (3) schizoaffective disorder (SA). The criteria used for the diagnosis of schizophrenia and affective disorder were essentially those of Feighner et al." The criteria used for the diagnosis of schizoaffective disorder were that a patient has either: (1) both schizophrenic and affective features; or (2) an affective episode, but in another episode an admixture of, or only, schizophrenic symptoms.'r' After this diagnostic exercise, the 35 pairs of sibs were grouped for the present study according to the six possible pairings of the three diagnoses: 11 ADAD, eight ADSA, four SASA, two ADSC, five SASC, and five SCSC.
RESULTS Is Schizoaffective Disorder Genetically Distinct From or Affective Disorder?—Out of a total of 70 a patients, diagnosis of schizophrenia was given to 17, schizoaffective disorder to 21, and affective disorder to 32.
Schizophrenia
If these three disorders are genetically distinct, one would expect the number of sib pairs both carrying a diagnosis of schizophrenia (SCSC) to be half of the total number of patients with schizophrenia, or 8.5 (17/2) as given in the Table. The observed number of SCSC pairs was five, and
the difference between the observed number and the expected number was not significant (P < .3). Likewise, the expected number of pairs of ADAD was 16 (32/2) and
Downloaded From: http://archpsyc.jamanetwork.com/ by a University of Toronto Libraries User on 12/12/2016
Observed and Expected Numbers of Sib Pairs Sib Pairs' SCSC SASA ADAD ADSA SASC
No.
No.
Observed
Expected
5
8.5
1.44
or
Ming
Tsuang, MD,
T.
Alive? PhD
\s=b\ Schizoaffective disorder, traditionally classified under schizophrenia, recently tends to be subsumed under affective disorder. This article reports a study of 35 sib pairs, where each six was independently diagnosed as having schizophrenia (SC), affective disorder (AD), or schizoaffective disorder (SA). The observed numbers of same-diagnosis pairs (ADAD, SASA, SCSC) were compared with the numbers expected if the three disorders are genetically independent. The results showed a significant deficiency only in the observed number of SASA pairs, which suggests that schizophrenia and affective disorder are genetically distinct whereas schizoaffective disorder is not.
To test whether schizoaffective disorder is a variant of affective disorder or schizophrenia, the observed number of ADSA and SASC pairs were compared against the expected numbers. No significant differences were found, which suggests that schizoaffective disorder is genetically heterogeneous, with at least two subtypes, one a variant of affective disorder, the other a variant of schizophrenia. (Arch Gen Psychiatry 36:633-634, 1979)
disorder has
been classified there is a strong to subsume schizoaffective disorder under affective disorder.-" On the other hand, although the available data do not convincingly support the concept that schizoaffective disorder is independent from schizophrenia or affective disorder, families who include many members affected with mixtures of schizophrenic and affective features have been reported. These reports suggest that schizoaffective disorder may be a genetically independent
traditionally Schi z oaffecti v e schizophrenia.1 However, tendency recently under
entity."·1-
Since the treatment of schizoaffective disorder depends greatly on how one views the nature of schizoaffective disorder, more research should be carried out to investigate what schizoaffective disorder really is. The present article Accepted
for publication Feb 12, 1979. From the Department of Psychiatry, University of Iowa College of Medicine, Iowa City. Reprint requests to the Department of Psychiatry, University of Iowa College of Medicine, 500 Newton Rd, Iowa City, IA 52242 (Dr Tsuang).
used data on sib pairs to answer two questions: (1) Is schizoaffective disorder genetically independent? (2) Is schizoaffective disorder a variant of affective disorder or
schizophrenia? SUBJECTS AND METHODS Case histories of 71 pairs of sibs who were both hospitalized for mental disorders'3 were studied. The conditions of all of these patients were diagnosed without knowledge of their sib relation¬ ships by Eliot Slater, MD, formerly director of the MRC Psychiat¬ ric Genetics Research Unit, Maudsley Hospital, University of London. In 35 of these pairs, the mental disorders seen were schizophrenia or affective disorder in both sibs, or schizophrenia in one and affective disorder in the other. Case histories of these 70 patients were given to George Winokur, MD, head of the Depart¬ ment of Psychiatry, University of Iowa, Iowa City, for rediagnosis of their conditions into three groups: (1) schizophrenia (SC), (2) affective disorder (AD), or (3) schizoaffective disorder (SA). The criteria used for the diagnosis of schizophrenia and affective disorder were essentially those of Feighner et al." The criteria used for the diagnosis of schizoaffective disorder were that a patient has either: (1) both schizophrenic and affective features; or (2) an affective episode, but in another episode an admixture of, or only, schizophrenic symptoms.'r' After this diagnostic exercise, the 35 pairs of sibs were grouped for the present study according to the six possible pairings of the three diagnoses: 11 ADAD, eight ADSA, four SASA, two ADSC, five SASC, and five SCSC.
RESULTS Is Schizoaffective Disorder Genetically Distinct From or Affective Disorder?—Out of a total of 70 a patients, diagnosis of schizophrenia was given to 17, schizoaffective disorder to 21, and affective disorder to 32.
Schizophrenia
If these three disorders are genetically distinct, one would expect the number of sib pairs both carrying a diagnosis of schizophrenia (SCSC) to be half of the total number of patients with schizophrenia, or 8.5 (17/2) as given in the Table. The observed number of SCSC pairs was five, and
the difference between the observed number and the expected number was not significant (P < .3). Likewise, the expected number of pairs of ADAD was 16 (32/2) and
Downloaded From: http://archpsyc.jamanetwork.com/ by a University of Toronto Libraries User on 12/12/2016
Observed and Expected Numbers of Sib Pairs Sib Pairs' SCSC SASA ADAD ADSA SASC
No.
No.
Observed
Expected
5
8.5
1.44
