Differential EEG Patterns in Affective Disorder and Schizophrenia Richard
Abrams, MD,
Michael Alan
Taylor,
MD
\s=b\ We analyzed the EEGs of 27 schizophrenic patients and 132 patients with affective disorder who received diagnoses according to rigorous research criteria. The proportion of abnormal EEGs was twice as great among schizophrenics as among affectives, and when the groups were compared for localized cortical differences, schizophrenics had more temporal abnormalities and affectives more parieto/occipital abnormalities. There was also a trend toward different hemispheric ateralization for the two groups, with a reversal of the relative proportions of left- and right-sided abnormalities. These differences were unrelated to age, sex, severity of illness, or past or present drug administration. These findings are complementary to those of other workers, lend support to the validity of our diagnostic research criteria, and provide additional evidence for neurophysiological differences between schizophrenics and patients with
affective disorder. (Arch Gen Psychiatry 36:1355-1358,
1979)
the
40 years have reported in patients with the and their have been the subject major of several recent reviews.1 :i Although there is agreement that a significant proportion of psychotic patients have abnormal EEGs, the precise nature of such abnormalities and their diagnostic specificity remain to be determined. More recently, Flor-Henry1 has shown left temporal EEG differences between schizophrenics and normal subjects and bitemporal lobe (mainly right-sided) EEG differences between manic-depressives and normal sub¬ jects by the use of computer-analyzed records that were
past investigators Manyresting EEG abnormalities psychoses, findings over
obtained while subjects were performing various neuropsychological tasks. No comparisons were made between the two patient groups, nor were specific patterns of
abnormality reported. The present study of visually analyzed scalp-recorded resting EEGs further evaluates cerebral functioning in patients with schizophrenia and affective disorder who received diagnoses according to rigorously applied research criteria. Based on previous reports and on our own neuropsychological test data,1 we predicted that the schizophren¬ ics would show more EEG abnormalities and more left temporal lobe abnormalities than patients with affective disorder who, in turn, would show more right-sided EEG abnormalities. METHOD The present study was done on short-term treatment university
psychiatric inpatient unit that served a suburban-rural population in New York State. All consecutive admissions for the 22 months ending in May 1976 were included. Each patient was interviewed by one of us and by a psychiatric resident who was specifically trained in principles of phenomenology and data collection and
Accepted
for publication June 29, 1979. From the Department of Psychiatry and Behavioral Sciences, University of Health Sciences/The Chicago Medical School, North Chicago, Ill, Reprint requests to Department of Psychiatry and Behavioral Sciences, University of Health Sciences/The Chicago Medical School, North Chicago, IL 60064 (Dr Abrams).
who followed a semistructured outline to collect the necessary clinical and demographic data. At the time of discharge, a summary was prepared for each patient that included all informa¬ tion and that was meticulously reviewed to ensure the accuracy and completeness of the data. After all data collection was completed, "blind" research diag¬ noses were made by one of us (R.A.) on the basis of the chief complaint, history of present illness, and mental status portions of the research records without any knowledge of patient-identi¬ fying information or demographic, family-history, neuropsychological, EEG, or treatment-response data. Research diagnoses were made according to the following criteria, which we have developed and validated in a series of clinical, family, neuropsychological, and treatment-response studies over the past six
years.6"" The criteria for
required)
schizophrenia (items
follows: of a through
1
through
4
were
were as
1. At least
one
c:
(a) Formal thought disorder-driveling, tangentiality, neologisms, paraphasias, non sequiturs, private words, stock words, word salad (6) First-rank symptoms-at least one (c) Emotional blunting—a constricted, inappropriate, unrelated affect of decreased intensity, with indiffer¬ for loved ones, lack of emotional and a loss of social graces 2. Clear consciousness 3. No diagnosable affective disorder 4. No diagnosable coarse brain disease, no past hallucinogen¬ ence or unconcern
responsivity,
ic or psychostimulant drug abuse, and no medical condi¬ tion known to cause schizophrenic symptoms The criteria for mania (items 1 through 4 were required) were as
1. 2. 3.
follows:
Hyperactivity Rapid or pressured speech Euphoric, expansive, or irritable mood, with
a broad affect 4. No diagnosable coarse brain disease, no psychostimulant drug abuse in the past month, and no medical illness known to cause manic symptoms The criteria for endogenous depression (items 1 through 3 were required) were as follows: 1. Sad, dysphoric, or anxious mood 2. Three of a through /:
(a) Early morning waking (b) Diurnal mood swing that is worse in the morning (c) A weight loss of more than 2.3 kg in three weeks (d) Retardation or agitation (e) Suicidal thoughts or behavior (/) Feelings of guilt, hopelessness, or worthlessness 3. No diagnosable coarse brain disease, no use of steroids or reserpine in the past month, and no medical illness known to cause depressive symptoms Application of these research criteria to a sample of consecutive phychiatric admissions yields admission-prevalence figures for schizophrenic and affective disorders that are the reverse of those generally reported in this country in the past. Such a reversal occurs when any stringent diagnostic criteria are systematically
Downloaded From: http://archpsyc.jamanetwork.com/ by a New York University User on 06/20/2015
employed, and we have recently shown'-' that our criteria yield admission-prevalence figures for schizophrenia that are exactly in the range of those found with the Feighner et al" criteria and the research diagnostic criteria14 and similar to those proposed for DSM-III. Our research criteria are also conceptually similar to the Feighner et al':' criteria in that we exclude patients who have diagnosable affective disorder prior to making a research diagno¬ sis of schizophrenia, thus giving priority to a diagnosis of affective disorder. In a recent survey, Pope and Lipinsky" have drawn attention to the consequences of the wide-spread overdiagnosis of schizophrenia (and underdiagnosis of affective disorder), pointing out, as we have also done,'2 that such diagnostic practices have undoubtedly confounded many past investigations and may account for the failure of so many studies to find specific biological abnormalities in schizophrenic patients. We chose to use rigorous research criteria to select homogeneous diagnostic groups for study. While this choice may make our data somewhat more difficult to compare with those of older studies, we believe it increases the likelihood of demonstrating significant between-
group differences. The severity of illness on admission to the hospital and during the subsequent 48 hours was determined at a separate time from the research diagnosis by a "blind" rater (R.A.) who was given the chief complaint, history of present illness, mental status, and hospital course portions of the research records, from which all notations of diagnostically specific psychopathology were deleted. Thus, rather than being informed that a patient had "thought broadcasting" (a first-rank symptom for schizophrenia), he was merely told that the patient had "a hallucination" (a nonspecific symptom). Severity ratings were based on the number, extent, and duration of the various psychopathological features (eg, hallucina¬ tions, delusions, abnormal motor behavior) and were coded on a scale with half-step increments from 0 (not ill) to 4 (most severely ill). Thus, our severity ratings were based on the form rather than the content of the psychopathology.
EEG
Scalp-recorded resting EEGs were routinely obtained in all cooperative patients in the clinical EEG laboratory of the univer¬ sity psychiatric service (director, R.A.). In every instance, we attempted to obtain EEGs prior to the initiation of psychotropic drug therapy, but where this was not possible because of illness severity, records were obtained after drug therapy had achieved a degree of clinical improvement. After an oral dose of 20 mL of chloral hydrate, resting EEGs of sufficient length to provide approximately 15 minutes of artifact-free awake recording and five minutes of sleep recording were obtained. An eight-channel electroencephalograph was employed with the use of the Interna¬ tional 10-20 electrode system with two unipolar and four bipolar
montages as follows: I: FP„ FP2; T:„ T4; T„ T„; 0„ 0,; all to linked ears II: F7, F„; T.,, T4; T-„ T„; 0„ 0..; all to linked ears III: FP,-FT, FT-T:„ T3-T:„ T.,-0,; FP.-F,, F,-T„ T,-T„, T,-02 IV: FP.-F,, F.-C C.-P,, P3-0,; FP2-F„ F,-C„ C,-P„ P4-02 V: F7-F„ F,-F,, F2-F4, F4-Fs; T,-C„ C,-Cz, Cz-C4, C,-T, VI: T:,,-C„ C,-Cz, Cz-C4, C4-T4; T,-P3( P,-Pz, Pz-P„ - „ All recordings included two periods of eye opening and closing and
hyperventilation. All records were coded by number and read by a "blind" examiner (R.A.) who did not have access to the patient's name, age, sex, diagnosis, or types of drugs received, if any. Using the descriptive criteria of Gibbs and Gibbs,1" each record was rated for the presence of one or more of the following abnormalities: slowing, spikes or sharp waves, slow bursts, suppression, asymmetry, sharp-slow bursts, and abnormal fast activity. When present, such abnormalities were further charac¬ terized as to their predominant cortical location and lateralization two minutes of
(eg, left or right frontal, temporal, parietal, or occipital) using the criterion of amplitude for unipolar montages and phase reversal for bipolar ones. Slowing was only rated as present if it occurred in association with alpha or low-voltage fast activity. Records with no abnormalities were classified as normal, records with minimal or mild abnormalities were classified as borderline, and those with moderate to severe abnormalities were classified as abnormal. A global classification such as this, which is based on visual estimates of pattern severity, is less precise than one based on a rating scale or on actual measurements of the record. However, the purpose of the study was to compare two groups of patients for the presence, severity, and distribution of EEG abnormalities, and as all records were read blind there was no way the method of classifying them could have introduced a systematic bias between groups. Statistical Analysis of Data Differences between
means were
analyzed by independent
t
tests, correlations by the Pearson product-moment correlation coefficient r, and contingency tables by raw -' (or Fisher's exact
probability where appropriate). Yates's correction for discontinui¬ ty was not used because
a number of workers have shown it to be conservative." In the analysis of the relation between research diagnosis and EEG abnormality, we used a hierarchical multiple-regression technique in which the investiga¬ tor determined the order of entry of the independent variables.21 In this way, we were able to account for the variance contributed by age, sex, severity of illness, past neuroleptic drug treatment, and present effects of drug treatment (neuroleptics or lithium carbonate) before testing the correlation between diagnosis and EEG abnormality.
inappropriately
L"
RESULTS A total of 465 patients were admitted during the study of whom 160 satisfied our research criteria for affective disorder (120 were manic, 40 depressed) and 31 satisfied our research criteria for schizophrenia. Of these, 159 (83%) had readable EEGs: 132 with affective disorder (101 manies, 31 depressives) and 27 schizophrenics.
period,
EEG Patterns
Of the entire sample, 28% had abnormal EEGs. Table 1 gives the distribution of all of the EEG abnormalities across research diagnoses and shows an excess of abnor¬ malities in the schizophrenic group ( - 9.56, two-tailed .048). This difference remains significant when borderline records alone are analyzed ( 5.92, one-tailed .025) or when just the abnormal ones are analyzed ( - 5.67, one-tailed .028). Therefore, these two groups were combined into a single "abnormal" group for analysis. Because schizophrenics had more EEG abnormal¬ ities than depressives alone ( - 8.65, one-tailed .002) and manies alone ( - 4.55, one-tailed .016) and because manies and depressives did not differ from each other ( 2.5, not significant [NS]), these latter two groups were also combined. When the two diagnostic groups are then compared, 48% of the schizophrenics have abnormal EEGs compared with 24% of the affectives .005). ( 6.81, one-tailed The cortical distribution of EEG abnormalities (Figure) was different for the two diagnostic groups, with an excess of temporal lobe abnormalities in the schizophrenic group ( - 4.08, one-tailed < .025) and parietooccipital-occipital abnormalities in the affective disorder group (twotailed exact .01). In fact, no schizophrenic patient =
=
=
=
=
=
=
=
=
=
=
=
Downloaded From: http://archpsyc.jamanetwork.com/ by a New York University User on 06/20/2015
=
=
=
diagnostic groups were due to differences in present drug administration, or severity of illness. There was no significant difference between the
showed parietooccipital abnormalities. There were also suggestive trends between groups for the lateralization of the EEG abnormalities. The eight schizophrenics with lateralized records showed a left/right, (L/R) distribution of 5/3 compared with a reversed L/R distribution of 6/15 for the 21 affective disorder patients with lateralized EEG abnormalities (exact .11). The cortical distribution of these lateralized abnormalities also tended to be different for the two groups, with 4/8 (50%) in the schizophrenic group showing left temporal abnormali¬ ties compared with only 2/21 (10%) in the affective disor¬ der group (exact .09). Right temporal abnormalities were equally prevalent in the two groups, with 2/8 (25%) of the schizophrenics and 6/21 (29%) of the affectives showing such changes (NS), but there was a trend (exact .11) for affectives to show more right parietooccipital abnor¬ malities than schizophrenics (6/21 [29%] in the former and 0/8 in the latter group). There were no differences between groups for the type of EEG abnormality recorded. Slow-wave activity was the predominant abnormality (70% of abnormal records of schizophrenics, 68% of abnormal records of affectives), followed by asymmetry (23% of schizophrenics, 19% of affectives), slow bursts (8% of schizophrenics, 10% of affectives), spikes or sharp waves (8% of schizophrenics, 9% of affectives), and abnormal fast activity (0% of schizo¬ phrenics, 3% of affectives). No seizure activity was observed. We considered the possibility that the observed differ-
60
| I
I
=
=
NS). ratio was quite different for the two diagnostic with a female-male ratio of 94:38 for the affectives groups, compared with 11:16 for the schizophrenics ( - 9.3, twotailed .003). However, the overall proportion of males with abnormal EEGs (20%) did not differ from that of females (31%) ( 2 2.18, two-tailed .136, NS), and there was no significant correlation between sex of patient and EEG abnormality (r .066, NS). An equivalent proportion of patients in each group were receiving drug treatment at the time their EEG was recorded (56% of the schizophrenics vs 52% of the affec¬ tives). More schizophrenics received neuroleptics and more affectively ill patients received lithium, alone or combined with neuroleptics, but there was no difference in the proportion of abnormal EEGs in each drug group (24%, 26%, and 29%). We also considered the possibility that drugs administered at the time of the EEG might have induced lateralized EEG abnormalities, but there were inadequate numbers of patients with lateralized EEGs who also received drugs to enable us to test any relationship between these two variables. Schizophrenics had a significantly greater mean lifetime hospital neuroleptic drug exposure than patients with affective disorder (30.3 months vs 11.1 months, < .05) as estimated by summing the total months of all hospitaliza¬ tions during which neuroleptics were received. However, there was no correlation for the entire sample between mean lifetime neuroleptic exposure in the hospital and The
=
=
or
r?
Abrams, MD,
Michael Alan
Taylor,
MD
\s=b\ We analyzed the EEGs of 27 schizophrenic patients and 132 patients with affective disorder who received diagnoses according to rigorous research criteria. The proportion of abnormal EEGs was twice as great among schizophrenics as among affectives, and when the groups were compared for localized cortical differences, schizophrenics had more temporal abnormalities and affectives more parieto/occipital abnormalities. There was also a trend toward different hemispheric ateralization for the two groups, with a reversal of the relative proportions of left- and right-sided abnormalities. These differences were unrelated to age, sex, severity of illness, or past or present drug administration. These findings are complementary to those of other workers, lend support to the validity of our diagnostic research criteria, and provide additional evidence for neurophysiological differences between schizophrenics and patients with
affective disorder. (Arch Gen Psychiatry 36:1355-1358,
1979)
the
40 years have reported in patients with the and their have been the subject major of several recent reviews.1 :i Although there is agreement that a significant proportion of psychotic patients have abnormal EEGs, the precise nature of such abnormalities and their diagnostic specificity remain to be determined. More recently, Flor-Henry1 has shown left temporal EEG differences between schizophrenics and normal subjects and bitemporal lobe (mainly right-sided) EEG differences between manic-depressives and normal sub¬ jects by the use of computer-analyzed records that were
past investigators Manyresting EEG abnormalities psychoses, findings over
obtained while subjects were performing various neuropsychological tasks. No comparisons were made between the two patient groups, nor were specific patterns of
abnormality reported. The present study of visually analyzed scalp-recorded resting EEGs further evaluates cerebral functioning in patients with schizophrenia and affective disorder who received diagnoses according to rigorously applied research criteria. Based on previous reports and on our own neuropsychological test data,1 we predicted that the schizophren¬ ics would show more EEG abnormalities and more left temporal lobe abnormalities than patients with affective disorder who, in turn, would show more right-sided EEG abnormalities. METHOD The present study was done on short-term treatment university
psychiatric inpatient unit that served a suburban-rural population in New York State. All consecutive admissions for the 22 months ending in May 1976 were included. Each patient was interviewed by one of us and by a psychiatric resident who was specifically trained in principles of phenomenology and data collection and
Accepted
for publication June 29, 1979. From the Department of Psychiatry and Behavioral Sciences, University of Health Sciences/The Chicago Medical School, North Chicago, Ill, Reprint requests to Department of Psychiatry and Behavioral Sciences, University of Health Sciences/The Chicago Medical School, North Chicago, IL 60064 (Dr Abrams).
who followed a semistructured outline to collect the necessary clinical and demographic data. At the time of discharge, a summary was prepared for each patient that included all informa¬ tion and that was meticulously reviewed to ensure the accuracy and completeness of the data. After all data collection was completed, "blind" research diag¬ noses were made by one of us (R.A.) on the basis of the chief complaint, history of present illness, and mental status portions of the research records without any knowledge of patient-identi¬ fying information or demographic, family-history, neuropsychological, EEG, or treatment-response data. Research diagnoses were made according to the following criteria, which we have developed and validated in a series of clinical, family, neuropsychological, and treatment-response studies over the past six
years.6"" The criteria for
required)
schizophrenia (items
follows: of a through
1
through
4
were
were as
1. At least
one
c:
(a) Formal thought disorder-driveling, tangentiality, neologisms, paraphasias, non sequiturs, private words, stock words, word salad (6) First-rank symptoms-at least one (c) Emotional blunting—a constricted, inappropriate, unrelated affect of decreased intensity, with indiffer¬ for loved ones, lack of emotional and a loss of social graces 2. Clear consciousness 3. No diagnosable affective disorder 4. No diagnosable coarse brain disease, no past hallucinogen¬ ence or unconcern
responsivity,
ic or psychostimulant drug abuse, and no medical condi¬ tion known to cause schizophrenic symptoms The criteria for mania (items 1 through 4 were required) were as
1. 2. 3.
follows:
Hyperactivity Rapid or pressured speech Euphoric, expansive, or irritable mood, with
a broad affect 4. No diagnosable coarse brain disease, no psychostimulant drug abuse in the past month, and no medical illness known to cause manic symptoms The criteria for endogenous depression (items 1 through 3 were required) were as follows: 1. Sad, dysphoric, or anxious mood 2. Three of a through /:
(a) Early morning waking (b) Diurnal mood swing that is worse in the morning (c) A weight loss of more than 2.3 kg in three weeks (d) Retardation or agitation (e) Suicidal thoughts or behavior (/) Feelings of guilt, hopelessness, or worthlessness 3. No diagnosable coarse brain disease, no use of steroids or reserpine in the past month, and no medical illness known to cause depressive symptoms Application of these research criteria to a sample of consecutive phychiatric admissions yields admission-prevalence figures for schizophrenic and affective disorders that are the reverse of those generally reported in this country in the past. Such a reversal occurs when any stringent diagnostic criteria are systematically
Downloaded From: http://archpsyc.jamanetwork.com/ by a New York University User on 06/20/2015
employed, and we have recently shown'-' that our criteria yield admission-prevalence figures for schizophrenia that are exactly in the range of those found with the Feighner et al" criteria and the research diagnostic criteria14 and similar to those proposed for DSM-III. Our research criteria are also conceptually similar to the Feighner et al':' criteria in that we exclude patients who have diagnosable affective disorder prior to making a research diagno¬ sis of schizophrenia, thus giving priority to a diagnosis of affective disorder. In a recent survey, Pope and Lipinsky" have drawn attention to the consequences of the wide-spread overdiagnosis of schizophrenia (and underdiagnosis of affective disorder), pointing out, as we have also done,'2 that such diagnostic practices have undoubtedly confounded many past investigations and may account for the failure of so many studies to find specific biological abnormalities in schizophrenic patients. We chose to use rigorous research criteria to select homogeneous diagnostic groups for study. While this choice may make our data somewhat more difficult to compare with those of older studies, we believe it increases the likelihood of demonstrating significant between-
group differences. The severity of illness on admission to the hospital and during the subsequent 48 hours was determined at a separate time from the research diagnosis by a "blind" rater (R.A.) who was given the chief complaint, history of present illness, mental status, and hospital course portions of the research records, from which all notations of diagnostically specific psychopathology were deleted. Thus, rather than being informed that a patient had "thought broadcasting" (a first-rank symptom for schizophrenia), he was merely told that the patient had "a hallucination" (a nonspecific symptom). Severity ratings were based on the number, extent, and duration of the various psychopathological features (eg, hallucina¬ tions, delusions, abnormal motor behavior) and were coded on a scale with half-step increments from 0 (not ill) to 4 (most severely ill). Thus, our severity ratings were based on the form rather than the content of the psychopathology.
EEG
Scalp-recorded resting EEGs were routinely obtained in all cooperative patients in the clinical EEG laboratory of the univer¬ sity psychiatric service (director, R.A.). In every instance, we attempted to obtain EEGs prior to the initiation of psychotropic drug therapy, but where this was not possible because of illness severity, records were obtained after drug therapy had achieved a degree of clinical improvement. After an oral dose of 20 mL of chloral hydrate, resting EEGs of sufficient length to provide approximately 15 minutes of artifact-free awake recording and five minutes of sleep recording were obtained. An eight-channel electroencephalograph was employed with the use of the Interna¬ tional 10-20 electrode system with two unipolar and four bipolar
montages as follows: I: FP„ FP2; T:„ T4; T„ T„; 0„ 0,; all to linked ears II: F7, F„; T.,, T4; T-„ T„; 0„ 0..; all to linked ears III: FP,-FT, FT-T:„ T3-T:„ T.,-0,; FP.-F,, F,-T„ T,-T„, T,-02 IV: FP.-F,, F.-C C.-P,, P3-0,; FP2-F„ F,-C„ C,-P„ P4-02 V: F7-F„ F,-F,, F2-F4, F4-Fs; T,-C„ C,-Cz, Cz-C4, C,-T, VI: T:,,-C„ C,-Cz, Cz-C4, C4-T4; T,-P3( P,-Pz, Pz-P„ - „ All recordings included two periods of eye opening and closing and
hyperventilation. All records were coded by number and read by a "blind" examiner (R.A.) who did not have access to the patient's name, age, sex, diagnosis, or types of drugs received, if any. Using the descriptive criteria of Gibbs and Gibbs,1" each record was rated for the presence of one or more of the following abnormalities: slowing, spikes or sharp waves, slow bursts, suppression, asymmetry, sharp-slow bursts, and abnormal fast activity. When present, such abnormalities were further charac¬ terized as to their predominant cortical location and lateralization two minutes of
(eg, left or right frontal, temporal, parietal, or occipital) using the criterion of amplitude for unipolar montages and phase reversal for bipolar ones. Slowing was only rated as present if it occurred in association with alpha or low-voltage fast activity. Records with no abnormalities were classified as normal, records with minimal or mild abnormalities were classified as borderline, and those with moderate to severe abnormalities were classified as abnormal. A global classification such as this, which is based on visual estimates of pattern severity, is less precise than one based on a rating scale or on actual measurements of the record. However, the purpose of the study was to compare two groups of patients for the presence, severity, and distribution of EEG abnormalities, and as all records were read blind there was no way the method of classifying them could have introduced a systematic bias between groups. Statistical Analysis of Data Differences between
means were
analyzed by independent
t
tests, correlations by the Pearson product-moment correlation coefficient r, and contingency tables by raw -' (or Fisher's exact
probability where appropriate). Yates's correction for discontinui¬ ty was not used because
a number of workers have shown it to be conservative." In the analysis of the relation between research diagnosis and EEG abnormality, we used a hierarchical multiple-regression technique in which the investiga¬ tor determined the order of entry of the independent variables.21 In this way, we were able to account for the variance contributed by age, sex, severity of illness, past neuroleptic drug treatment, and present effects of drug treatment (neuroleptics or lithium carbonate) before testing the correlation between diagnosis and EEG abnormality.
inappropriately
L"
RESULTS A total of 465 patients were admitted during the study of whom 160 satisfied our research criteria for affective disorder (120 were manic, 40 depressed) and 31 satisfied our research criteria for schizophrenia. Of these, 159 (83%) had readable EEGs: 132 with affective disorder (101 manies, 31 depressives) and 27 schizophrenics.
period,
EEG Patterns
Of the entire sample, 28% had abnormal EEGs. Table 1 gives the distribution of all of the EEG abnormalities across research diagnoses and shows an excess of abnor¬ malities in the schizophrenic group ( - 9.56, two-tailed .048). This difference remains significant when borderline records alone are analyzed ( 5.92, one-tailed .025) or when just the abnormal ones are analyzed ( - 5.67, one-tailed .028). Therefore, these two groups were combined into a single "abnormal" group for analysis. Because schizophrenics had more EEG abnormal¬ ities than depressives alone ( - 8.65, one-tailed .002) and manies alone ( - 4.55, one-tailed .016) and because manies and depressives did not differ from each other ( 2.5, not significant [NS]), these latter two groups were also combined. When the two diagnostic groups are then compared, 48% of the schizophrenics have abnormal EEGs compared with 24% of the affectives .005). ( 6.81, one-tailed The cortical distribution of EEG abnormalities (Figure) was different for the two diagnostic groups, with an excess of temporal lobe abnormalities in the schizophrenic group ( - 4.08, one-tailed < .025) and parietooccipital-occipital abnormalities in the affective disorder group (twotailed exact .01). In fact, no schizophrenic patient =
=
=
=
=
=
=
=
=
=
=
=
Downloaded From: http://archpsyc.jamanetwork.com/ by a New York University User on 06/20/2015
=
=
=
diagnostic groups were due to differences in present drug administration, or severity of illness. There was no significant difference between the
showed parietooccipital abnormalities. There were also suggestive trends between groups for the lateralization of the EEG abnormalities. The eight schizophrenics with lateralized records showed a left/right, (L/R) distribution of 5/3 compared with a reversed L/R distribution of 6/15 for the 21 affective disorder patients with lateralized EEG abnormalities (exact .11). The cortical distribution of these lateralized abnormalities also tended to be different for the two groups, with 4/8 (50%) in the schizophrenic group showing left temporal abnormali¬ ties compared with only 2/21 (10%) in the affective disor¬ der group (exact .09). Right temporal abnormalities were equally prevalent in the two groups, with 2/8 (25%) of the schizophrenics and 6/21 (29%) of the affectives showing such changes (NS), but there was a trend (exact .11) for affectives to show more right parietooccipital abnor¬ malities than schizophrenics (6/21 [29%] in the former and 0/8 in the latter group). There were no differences between groups for the type of EEG abnormality recorded. Slow-wave activity was the predominant abnormality (70% of abnormal records of schizophrenics, 68% of abnormal records of affectives), followed by asymmetry (23% of schizophrenics, 19% of affectives), slow bursts (8% of schizophrenics, 10% of affectives), spikes or sharp waves (8% of schizophrenics, 9% of affectives), and abnormal fast activity (0% of schizo¬ phrenics, 3% of affectives). No seizure activity was observed. We considered the possibility that the observed differ-
60
| I
I
=
=
NS). ratio was quite different for the two diagnostic with a female-male ratio of 94:38 for the affectives groups, compared with 11:16 for the schizophrenics ( - 9.3, twotailed .003). However, the overall proportion of males with abnormal EEGs (20%) did not differ from that of females (31%) ( 2 2.18, two-tailed .136, NS), and there was no significant correlation between sex of patient and EEG abnormality (r .066, NS). An equivalent proportion of patients in each group were receiving drug treatment at the time their EEG was recorded (56% of the schizophrenics vs 52% of the affec¬ tives). More schizophrenics received neuroleptics and more affectively ill patients received lithium, alone or combined with neuroleptics, but there was no difference in the proportion of abnormal EEGs in each drug group (24%, 26%, and 29%). We also considered the possibility that drugs administered at the time of the EEG might have induced lateralized EEG abnormalities, but there were inadequate numbers of patients with lateralized EEGs who also received drugs to enable us to test any relationship between these two variables. Schizophrenics had a significantly greater mean lifetime hospital neuroleptic drug exposure than patients with affective disorder (30.3 months vs 11.1 months, < .05) as estimated by summing the total months of all hospitaliza¬ tions during which neuroleptics were received. However, there was no correlation for the entire sample between mean lifetime neuroleptic exposure in the hospital and The
=
=
or
r?
