Neurasthenia: cross-cultural and conceptual issues in relation to chronic fatigue syndrome.

The purpose of this study was to examine several conceptual and cross-cultural issues in neurasthenia, particularly in terms of their relationship to chronic fatigue syndrome. A review of this relationship led to the conclusion that these conditions are much more alike in Western countries than in countries such as China, where neurasthenia could almost be regarded as a "culture-bound syndrome." This may be a consequence of factors such as the heterogeneous nature of neurasthenia and different diagnostic practices in different countries, despite the ICD-10 definition of neurasthenia, intended for worldwide use. Likewise, there is no consensus on what the "core" characteristics of neurasthenia are, because its clinical presentation and key features in different countries are very different. Despite the finding of relatively low comorbidity rates between neurasthenia and other mental disorders, clinical experience suggests that features of neurasthenia frequently overlap with those of depression, chronic anxiety, and somatoform disorders. There is no convincing evidence that in cases of overlap or comorbidity, other diagnoses should automatically have "primacy" over neurasthenia nor should the diagnosis of neurasthenia thereby be excluded. Although some aspects of its validity have improved recently, especially its descriptive validity, the overall validity of the diagnosis of neurasthenia is still not satisfactory. Suggestions for further research, aimed at improving the diagnostic validity of neurasthenia, are offered in this paper.