정신분열증의 증상 유형과 항정신병약물 투여가 대뇌비대칭성에 미치는 영향

Abstract

[한글]

오늘날 대표적인 정신분열증의 분류 방법 중 하나는 정신분열증을 양성증상군과 음성중상군으로 분류하는 것이다. 그러나 이러한 분류에 있어 가장 중요한 생물학적 근거로 제시된 뇌실의 변화 차이, 즉 양성증상군에서는 뇌실 크기의 변화가 없으나 음성증상군에서

는 뇌실의 크기가 증가한다는 것이 최근 연구들에서 부정되므로써, 정신분열증 분류에 있어 새로운 생물학적 기준을 찾는 연구들이 이루어지고 있다. 그러한 연구들에서 제기되고 있는 중요한 질문 중 하나가 정신분열증과 대뇌비대칭성과의 관련성이다. 그동안 정신분열증은 좌반구의 기능장애와 관련된 질환으로 알려져 왔다. 그러나 최근의 연구들은 그와 상반되는 결과들을 보고하기도 하여 아직 명확하게 규명되지 못하고 있는 실정이다. 이와 같이 정신분열증의 대뇌비대칭성에 대한 연구 결과들이 일관성 없이 나타나는 이유는, 그 실험들이 정신분열증의 증상 유형을 고려하지 않고 이루어져서 나타난 것이라 볼 수 있다.

본 연구에서는 정신분열증 증상을 양성증상과 음성증상으로 분류하여 그 각각에서의 대뇌비대칭성을 비교하고, 항정신병약물이 정신분열증 각 증상군의 대뇌비대칭성에 기치는 영향을 비교하였다.

본 연구는 정상군과 정신분열증 비투약군, 정신분열증 투약군 각각 29명을 대상으로 하였다. 정신분열증의 증상과 유형을 평가하는 도구로서 PANSS(Positive and Negative Syndrome Scale for Schizophrenia)를 이용하였다. 투약군에게 투여된 항정신병약물은 현재 대표적인 정신분열증 치료제로 사용되고 있는 haloperidol 이었다. 대뇌비대칭성의 측정은 반시야(visual hemifield)를 이용한 순간노출기법(tachistoscopic method)을 이용하였다. 이때 측정한 변수는 정답률과 반응시간이었다. 그에 따라 정답률의 편측비와 반응시간의 편측비도 구하였다.

통계처리는 각 실험군에 있어 정답률, 반응시간, 정답률 편측비, 반응시간 편측비 각각에 대하여 집단 조건, 시야 조건, 글자종류 조건, 글자수 조건을 ANOVA 통계처리 하였고 정신분열증 환자군(비투약군, 투약군)에 있어 PANSS를 통하여 측정한 5개의 하위척도 점수와 실험을 통해 측정된 정답률의 편측비, 반응시간의 편측비의 상관관계를 Pearson's correlation test로 검증하였다. 또한 PANSS의 30개 증상 각각의 점수와 정답률, 반응시간, 정답률 편측비, 반응시간의 편측비와의 상관관계를 Pearson's correlation test로 검증하였다.

본 연구는 다음과 같은 결론을 얻었다.

1. 정신분열증 환자는 정답률 및 반응시간에' 있어 좌, 우반구 기능 모두가 정상인에 비하여 감소하였으며, 특히 정답률에 있어서는 우반구에서 유의하게 감소한 반면, 반응시간의 감소에 있어서는 좌우반구의 차이가 없었다.

2. 정신분열증 비투약군의 증상을 PANSS 하위척도에 의하여 평가하였을 때, 양성척도 점수와 대뇌비대칭성(편측비) 간에는 상관관계가 있었던 반면에, 음성척도 점수와는 상관관계가 없었다. 또한 증상점수와 편측비간에 상관관계가 있는 증상들은 대부분 양성증상들 이었으며, 음성증상들 중에는 상관관계가 있는 증상이 거의 없었다.

3. 항정신병약물 투여는 정신분열증 환자에 있어 전체적으로 인지과제 수행능력, 특히 반응속도를 증가시키는 경향이 있었고, 대뇌비대칭성(편측비)에 대하여는 다소 정상화 시켰으나 유의하지는 않았다. 그러나 항정신병약물은 대뇌비대칭성(편측비) 정도와 양성척

도, 일반척도 및 총척도 점수와의 상관관계를 유의하게 증가시켰으며, 반면에 음성척도와의 상관관계에는 아무런 영향을 끼치지 않았다. 또한 비투약군에 비하여 투약군에서는 정답률 및 반응시간의 편측비와 유의한 상관관계가 있는 점수의 양성증상과 일반증상 항목수가 뚜렷하게 증가한 반면에 음성증상에서는 투약에 의한 차이가 나타나지 않았다.

이상의 결과를 종합하여 볼 때 본 실험은 첫째, 정신분열증이 단순히 좌반구장애에 의한다는 기존 가설은 재검토 되어야하며, 대뇌비대칭성에 있어 정답률과 반응시간은 각기 다른 대뇌 기전에 의하여 수행됨을 시사한다. 둘째, 정신분열증의 양성중상과 음성증상은 대뇌비대칭성에 있어 서로 다른 기전을 가지고 있다고 보여지는바 즉 대뇌비대칭성과 관계되는 것은 양성증상들이고 음성증상들은 대뇌비대칭성과 관계가 없음을 시사한다. 세째, 항정신병약물은 정신분열증의 대뇌비대칭성을 정상화하는 경향이 있으나 유의하지는 않았다. 그러나 대뇌비대칭성은 양성증상과 관련이 있고 음성증상과는 관련이 없다는 것이 약물투여로 인하여 더 강하게 시사되었다. 이모든 결과는 정신분열증의 양성증상과 음성증상이 각기 다른 신경 생리적 기전을 가지고 있을 가능성을 시사한다.

Effect of the clinical subtypes of schizophrenia and Antipsrchotics on Brain

Asymmetricity

Woo Taek Jeon

Department of Medical Science The Graduate School, Yonsei University

(Directed by Professor Sung Kil Min)

Schizophrenia is classified into the Positive syndrome and the negative syndrome

according to the representative symptom pattern. However, this classification was

criticized by recent studies because the different size of the brain ventricles of

each syndrome which were regarded as the most important biological basis of this

classification were not observed consistently. On the other hand, many studies had

reported that schizophrenia was related to the dysfunction of the left hemisphere.

However some studies have reported contradictory results. It is supposed that the

reason for the different study results of the relationship between schizophrenia

and brain asymmetry is that previous studies did not consider the classification of

positive and negative subtypes of schizophrenia. The purpose of this study is to

investigate the brain asymmetricity in relation to positive and negative syndromes

of schizophrenia and the effect of antipsychotics upon this brain asymmetricity

pattern.

The subjects of this study were 29 normal control subjects, 29 schizophrenia

non-medicated patients and 29 schizophrenia medicated patients. PANSS(Positive and

Negative Syndrome Scale for Schizophrenia ) was used for symptom evaluation. In

method, the visual hemifield method with tachistoscopic technique was used for

recognition of Hangul and Chinese words and the subjects were instructed to read

the words as fast as possible. The correct response rate, the response time and the

laterality score(ratio of [left-right/left+right]) of the correct response rate and

response time were measured.

The results are as follows;

1. In schizophrenia, the correct response rate decreased and the response time

was delayed in comparison with the normal controls. In schizophrenia, only the

right hemisphere had a statistically significant decrease in the correct response

rate, while in the response time, there was no significant difference between the

left and right hemisphere.

2. In the schizophrenia non-medicated group, the positive symptom score highly

correlated with the brain asyrnmetricity(laterality score), but the negative

symptom score did not show such a correlation. Also, the symptom items which had a

statistically significant correlation with the laterality score were almost all

positive symptom items and rarely negative symptom items.

3. Antipsychotics medication to schizophrenic patients generally decreased the

ability of cognitive task performance and delayed the reaction time. And

antipsychotics decreased the laterality score in schizophrenia patients, but it was

not statistically significant. Antipsychotics increased the correlation of

laterality score with the positive symptom score, the general psychopathology

symptom score and the total score of PANSS but not with the negative symptom score.

In comparison with the non-medicated schizophrenia group, the medicated

schizophrenia group had more positive symptom items and general psychopathology

symptom items which had significant correlations with the laterality score of the

correct response rate and the laterality score of the reacpion time, but had no

negative symptom items.

These results suggest that the hypothesis that schizophrenia is related with the

dysfunction of the left hemisphere should be reexamined, and that the correct

response rate and the response time have a different mechanisms in the brain

information process also, that the positive symptoms have a correlation with brain

asymmetricity but negative symptoms do not, and that the antipsychotics have the

tendency to normalize the brain asymmetricity in schizophrenia; and finally that

the positive symptoms and the negative symptoms of schizophrenia have different

neurophysiological mechanisms.

[영문]

Schizophrenia is classified into the Positive syndrome and the negative syndrome according to the representative symptom pattern. However, this classification was criticized by recent studies because the different size of the brain ventricles of

each syndrome which were regarded as the most important biological basis of this classification were not observed consistently. On the other hand, many studies had reported that schizophrenia was related to the dysfunction of the left hemisphere.

However some studies have reported contradictory results. It is supposed that the reason for the different study results of the relationship between schizophrenia and brain asymmetry is that previous studies did not consider the classification of positive and negative subtypes of schizophrenia. The purpose of this study is to investigate the brain asymmetricity in relation to positive and negative syndromes of schizophrenia and the effect of antipsychotics upon this brain asymmetricity pattern.

The subjects of this study were 29 normal control subjects, 29 schizophrenia non-medicated patients and 29 schizophrenia medicated patients. PANSS(Positive and Negative Syndrome Scale for Schizophrenia ) was used for symptom evaluation. In method, the visual hemifield method with tachistoscopic technique was used for recognition of Hangul and Chinese words and the subjects were instructed to read the words as fast as possible. The correct response rate, the response time and the laterality score(ratio of [left-right/left+right]) of the correct response rate and response time were measured.

The results are as follows;

1. In schizophrenia, the correct response rate decreased and the response time was delayed in comparison with the normal controls. In schizophrenia, only the right hemisphere had a statistically significant decrease in the correct response

rate, while in the response time, there was no significant difference between the left and right hemisphere.

2. In the schizophrenia non-medicated group, the positive symptom score highly correlated with the brain asyrnmetricity(laterality score), but the negative

symptom score did not show such a correlation. Also, the symptom items which had a statistically significant correlation with the laterality score were almost all positive symptom items and rarely negative symptom items.

3. Antipsychotics medication to schizophrenic patients generally decreased the ability of cognitive task performance and delayed the reaction time. And antipsychotics decreased the laterality score in schizophrenia patients, but it was not statistically significant. Antipsychotics increased the correlation of laterality score with the positive symptom score, the general psychopathology symptom score and the total score of PANSS but not with the negative symptom score.

In comparison with the non-medicated schizophrenia group, the medicated schizophrenia group had more positive symptom items and general psychopathology symptom items which had significant correlations with the laterality score of the correct response rate and the laterality score of the reacpion time, but had no

negative symptom items.

These results suggest that the hypothesis that schizophrenia is related with the dysfunction of the left hemisphere should be reexamined, and that the correct response rate and the response time have a different mechanisms in the brain information process also, that the positive symptoms have a correlation with brain

asymmetricity but negative symptoms do not, and that the antipsychotics have the tendency to normalize the brain asymmetricity in schizophrenia; and finally that the positive symptoms and the negative symptoms of schizophrenia have different neurophysiological mechanisms.