• bipolar disorder;
  • community psychiatry;
  • disaster psychiatry;
  • mania;
  • radioactive hazard release


  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References


The Fukushima disaster was caused by an earthquake that occurred on 11 March 2011. Following the serious damage caused by the earthquake and the subsequent tsunami, radioactive contamination occurred because of the meltdown accident at the Fukushima nuclear power plant. We investigated what mental disorders were likely to become exacerbated under these conditions.


We surveyed psychiatric outpatients at Fukushima Medical University Hospital for 1 month (31 days) from the day of the earthquake (March–April 2011).


The survey revealed that bipolar I disorder was most likely to become exacerbated under the conditions and that the exacerbation exhibited was more likely to involve manic switches than depression.


On the basis of the results of our study, particular care must be taken to follow up bipolar I disorder patients after a natural disaster. Our results also suggested the possible origin of bipolar I disorder.

The Fukushima disaster was caused by an earthquake that occurred on 11 March 2011. The high-magnitude earthquake followed by tsunami damaged the Fukushima I nuclear power plant, also known as the Fukushima Dai-ichi nuclear power plant, causing a meltdown accident and radioactive contamination. The exacerbation of mental disorders after natural disasters has been studied previously,[1] including studies on earthquakes,[2, 3] hurricanes,[4-6] and tsunamis.[7] Radioactive contamination due to nuclear accidents or atomic bombs, which occurred as separate events from natural disasters, have been conducted after historical events, such as the Chernobyl,[8-12] Three Mile Island,[13] Hiroshima, and Nagasaki disasters.[14] However, the Fukushima disaster was a complex and unique case, because it was a combination of a natural disaster and radioactive contamination. Therefore, the effects of such conditions on mental disorders are unknown.

In an event of radioactive contamination, people are generally unaware or uncertain about the situation and the extent of disaster, because the condition is not easily comprehensive, and people do not know how to handle such a situation. In addition, after exposure, the duration during which health problems manifest is unknown.[15] It is a mission of historical significance to report on how mental disorders are affected by a stressful situation, characterized by the fear of invisible radioactive contamination along with tremendous stress due to the knowledge of loss of lifelines during a natural disaster. Fukushima Medical University Hospital is located 60 km from the Fukushima I nuclear power plant, where the meltdown accident occurred; this hospital is affiliated to the only university in Fukushima Prefecture with a Faculty of Medicine. We previously compiled a report at our clinic on the kind of mental disorders that were most likely to occur due to Fukushima disaster (Matsumoto et al. in submission), in which several severe acute stress disorders were apparent.

In this study, we conducted a general survey of patients who were suffering from some mental disorders and attending psychiatric follow-up appointments. We investigated which mental disorders tended to become exacerbated in a situation like the Fukushima disaster and identified points of caution that will require consideration when treating psychiatric outpatients during future complex disasters.


  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References


We surveyed psychiatric outpatients at Fukushima Medical University Hospital for 1 month (31 days) from the day of the earthquake, that is, from 14.46 hours 11 March to 14.46 hours 11 April 2011. This study was approved by the Ethics Committee of Fukushima Medical University and complied according to the Declaration of Helsinki. The subjects of our study were psychiatric outpatients who were attending follow-up examination by three psychiatrists with 10, 9, and 4 years of clinical experience, respectively. We excluded the following patients: those who first visited our department after the earthquake disaster, those who had been attending a different hospital, and those who were experiencing symptoms for the first time. We also excluded patients who had been hospitalized during the earthquake on 11 March, but were discharged after the earthquake disaster and visited the hospital for an examination before 11 April. Thus, we only investigated patients who were regularly attending examinations as an outpatient.

As mentioned above, during the study period after 11 March, 1613 patients visited the Fukushima Medical University Hospital Department of Psychiatry as outpatients. We excluded the second and subsequent visits of patients who attended multiple examinations, and patients who visited our department for the first time after 11 March. Patients who were hospitalized on 11 March but discharged within 1 month after which they returned for an examination were also excluded. We also excluded 13 patients who did not require consultation with a doctor on their visit (counseling with a psychologist without medical examination, a test or examination, or participation in day care). As a result, the actual number of subjects was 1286 regular outpatients. We examined the medical records of 1273 patients who consented to investigation.


We divided the patients in our investigation into different diagnosis groups according to ICD-10.[16] We divided the patients into 10 mental disorders groups: F0–F9 and G. For example, group F0 included dementia patients, group F2 included schizophrenia patients, group F9 included attention-deficit hyperactivity disorder patients, and group G included patients with diseases of the nervous system, such as epilepsy and narcolepsy, restless legs syndrome, migraine, and Parkinson's syndrome. Disorders that could be classified according to ICD-10 as either F or G, for example, Alzheimer's disease, were classified as belonging to group F. Patients diagnosed with multiple disorders were classified according to their principal disorder. Patients attending follow-up examinations for their principal disorder at other departments were classified according to the diagnosis of the symptoms; this necessitated their visit to our department. Only group F3 (mood disorders) was divided into bipolar disorder and other mood disorders because of the vast differences in the pathology of depression in a mood disorder and a bipolar disorder despite both being classified as F3. These differences were due to considerable differences in the blood and post-mortem brain microarray analysis,[17] the necessity of medication, such as mood stabilizers, and the variation in the response to antidepressants.[18] We also divided bipolar disorder into type I and type II, in accordance with the DSM-IV.[19] We confirmed patients’ diagnoses with their medical records, and verified whether their doctor had evaluated them to be those showing improvement, no change, or exacerbation.

Statistical analysis

Statistical analysis involved verifying whether a significant difference existed between the groups using the Kruskal–Wallis test, and confirmed the significant differences using the Steel–Dwass procedure for multiple comparison. We set the significance level at P < 0.05 (two-tailed test). These statistics were performed by the Ekuseru-Toukei 2010 (Social Survey Research Information, Tokyo, Japan).


  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References

Table 1 shows a detailed breakdown of the 1273 subjects in this study.

Table 1. Summary of the regular outpatients who visited our hospital during the 1-month period after the Fukushima disaster
ICD codeDiseasePrincipal disorderTotalAge (years)SexImprovement or no changeExacerbationExacerbation rate
  1. Out of 1273 subjects, only 13 showed improvements, 1145 showed no change, and 115 exhibited an exacerbation in their condition.

  2. ADHD, attention-deficit hyperactivity disorder; F, female; M, male.

GDiseases of the nervous systemEpilepsy12341.6 ± 17.963 F, 60 M11940.0325
F7Mental retardationMental retardation2229.9 ± 15.010 F, 12 M2110.0455
F9Behavioral and emotional disorders with onset usually occurring in childhood and adolescenceADHD6521.8 ± 12.312 F, 53 M6230.0462
F0Organic, including symptomatic, mental disordersDementia12772.8 ± 14.775 F, 52 M12070.0551
F5Behavioral syndromes associated with physiological disturbances and physical factorsEating disorder1724.8 ± 10.814 F, 3 M1610.0588
F3Mood disorders, exclude bipolar disorderUnipolar depression21852.0 ± 16.8124 F, 94 M204140.0642
F2Schizophrenia, schizotypal and delusional disordersSchizophrenia22644.3 ± 14.4113 F, 113 M211150.0664
F1Mental and behavioral disorders due to psychoactive substance useAlcoholism1957.6 ± 17.13 F, 16 M1820.1000
F8Disorders of psychological developmentAutism, Asperger's syndrome6824.6 ± 12.123 F, 45 M6080.1177
F4Neurotic, stress-related and somatoform disordersAnxiety disorder, somatoform disorder29947.1 ± 19.5190 F, 109 M257410.1376
F6Disorders of adult personality and behaviorPersonality disorder2542.5 ± 16.718 F, 7 M2140.1600
F3Bipolar II disorderBipolar II disorder2544.1 ± 12.214 F, 11 M2050.2000
F3Bipolar I disorderBipolar I disorder3951.9 ± 18.718 F, 21 M29100.2564
   127346.5 ± 20.4677 F, 596 M11581150.0903

Figure 1 shows that the exacerbation rate was significantly higher in the group with bipolar I disorder than group G, group F0, group F3 excluding bipolar disorder, and group F2. The rate was marginally significantly higher in the group of bipolar I disorder than group F9. The rate was significantly higher in the group with bipolar II disorder than group G and was also significantly higher in group F4 than group G.


Figure 1. Exacerbation rates by diagnostic groups in regular outpatients who visited the Fukushima Medical University Hospital Department of Psychiatry during the 1-month period after the Fukushima disaster. The exacerbation rate was significantly higher in the group of bipolar I disorder patients than in group G, group F0, group F3 excluding bipolar disorder, and group F2. The rate was marginally significantly higher in the group of bipolar I disorder patients than in group F9. The rate was significantly higher in the group of bipolar II disorder patients than in group G and was also significantly higher in group F4 than in group G. Error bars show interval estimations.

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Table 2 indicates that exacerbation in bipolar I disorder led to depression in three of 10 patients, while seven patients switched to a manic state.

Table 2. Exacerbation of bipolar disorder
 ImprovementNo changeDepressive switchManic switchTotal
  1. Of total 39 bipolar I disorder patients, 7 of the 10 whose symptoms had exacerbated exhibited a manic switch. In contrast, out of the 25 bipolar II disorder patients, only 2 of 5 patients whose symptoms became exacerbated entered a hypomanic state, while 3 became exacerbated and entered a depressive state.

Bipolar I disorder1283739
Bipolar II disorder0203225


  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References

Rather than focusing on new mental disorders as a result of the disaster, this study, as already mentioned in the Introduction section, aimed to investigate which mental disorders became exacerbated in patients who were diagnosed with disorder and attending return follow-up examinations. Therefore, our results revealed little change in the condition of most patients. This result is consistent with the data gathered during the week following the earthquake by Saito.[20] Because a treatment for mental disorder requires months to years to stabilize, it is rare for changes in symptoms to manifest within a month. In other words, regular psychiatric outpatients should normally not exhibit any changes within a month-long investigation period. Hence, in psychiatry, a patient's stable condition over days or weeks is not indicative of a successful treatment. Many patients in the study were observed to be upset by this unprecedented event. Manic switches in bipolar I disorder were particularly salient in clinical experience during the Fukushima disaster.[21] Thus, it was necessary to investigate which mental disorders are likely to become exacerbated under the influence of a complex disaster with radioactive contamination.

Our study confirmed that bipolar I disorder was the most likely mental disorder to become exacerbated. This was consistent with our empirical understanding of the Fukushima disaster. In addition, bipolar II disorder also appeared likely to become exacerbated. Considering the exacerbation symptoms, exacerbation of bipolar I disorder was more likely to involve manic switches, and bipolar II disorder patients were more likely to experience depression. The research results from an investigation of bipolar disorder patients whose condition deteriorated after a hurricane indicated that instability in the original condition of the disease often led to a relapse.[4] Manic switches in bipolar I disorder generate extreme stress on the families, surrounding local community, and the medical staff involved in treating the patients. This condition due to a disaster can easily lead to indirect damage, and therefore, requires particular attention. In hospitals that have insufficient resources, patients with intense manic switches require more staff attention compared to patients hospitalized due to other reasons; this causes a relative lack of care for the latter. Therefore, it is important to ensure that the symptoms of patients with bipolar I disorder do not exacerbate into a manic state during a disaster.

Catastrophes generally expose people to a great amount of stress.[22, 23] The ICD-10 Classification of Mental and Behavioural Disorders: Clinical Descriptions and Diagnostic Guidelines state that reactions to severe stress may include acute stress reactions, where psychiatric symptoms occur within minutes, and post-traumatic stress disorder, which occurs after an incubation period of a few weeks or months after a strong traumatic experience. Mental disorders that occur within 1 month after the stress change can also include adjustment disorder. We wrote a report regarding the above stress reactions during the 3 weeks after the Fukushima disaster targeting new outpatients (Matsumoto et al. in submission). This report suggests that acute stress reactions and reactions to severe stress were related to the onset of mental disorders.

Although the above-mentioned report investigated new manifestations of mental disorders, the purpose of the present study was to examine the development of mental disorders that had been diagnosed before the complex disaster. The most characteristic feature of the Fukushima disaster, which is unlike any previous disasters and which is unprecedented throughout the world, is that it combines the direct psychological shock of a natural disaster with the stress of persistent anxiety of sustained exposure to radioactive contamination.[15] Therefore, it is not surprising that the exacerbation rate of F4, which includes stress-related disorders, was also high in this study.

Next, we discussed why the exacerbation rate of bipolar disorder was higher than that of stress-related disorders in group F4. Several theories can explain the origin of mental disorders.[24-26] The point here is why, despite having social disadvantages, are these factors not eliminated? The possible reason could be that the characteristics that cause these disorders are important in the struggle for existence.[24-26] In a situation such as the Fukushima disaster, the nature of the social circumstances causes people to revert to a primitive state, because of the extreme scarcity of resources and the competition to access it. In bipolar I disorder patients, when they encounter a critical situation in which their very existence is threatened, the mechanism which causes them to switch to a higher activity level of manic mode in an attempt to overcome the crisis probably functions. Thus, exacerbation of bipolar disorder differs qualitatively from the pure exacerbation symptoms of F4, and hence, it should not be considered from the same perspective. In bipolar disorder, a manic switch that occurs when the patient is under extreme stress, such as during a disaster, may not necessarily be deterioration in symptoms but a probable defense mechanism called ‘manic defense’. However, it remains to be elucidated why other psychiatric disorders without bipolar disorder tended not to develop ‘manic defense’ and a manic switch. It is suggested that some unexplained mechanisms specific to bipolar disorders might be implicated in manic switch, which may additionally lead to one of the potential causes of this disease itself. The exacerbation rate in group G was possibly the lowest, because this group included organic diseases, which are not easily influenced by psychological stress. The F0 group primarily included dementia patients. The insufficient cognitive function seen in dementia patients could indicate that they are not able to feel stress, because it is difficult for them to perceive the actual situation surrounding them. However, since patients with dementia had variations of diagnosis and a degree of cognitive dysfunction, then this issue may not be so simple.

Although we have discussed the overall changes in symptoms of all mental disorders, we believe that for each disease, individual evaluation criteria should be used because the implications and extent of exacerbation vary according to the type of disease. We have not been able to accurately present the extent of exacerbation in this study because we have compiled items with differing implications. The present study also has other methodological limitations. The follow-up examinations were conducted by three non-blinded psychiatrists, so there may have been some bias. However, despite this limitation, our study is an important evaluation of the effect of disasters on mental disorders. Furthermore, because we used the ICD classification system, our results can be further divided according to more detailed diagnoses. The results of our study should be interpreted on the basis of the above-mentioned points.


  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References

This report is a reflection of our clinical activities during the first month of the Fukushima disaster, which could have been written by any of our colleagues. Thus, we wish to express our sincere thanks to all our colleagues, whose devotion, professionalism, and dedication were essential in the battlefield-like conditions in the outpatient department, but are not listed as authors of this manuscript. In statistical analysis in this paper we are thankful for the help of Professor Tatsuya Okada, Department of Mathematics and Statistics, School of Medicine, Fukushima Medical University. The authors declare that they have no conflict of interest.


  1. Top of page
  2. Abstract
  3. Methods
  4. Results
  5. Discussion
  6. Acknowledgments
  7. References
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