Letters to the Editor
The Symptoms of Atypical Depression
Dear Editor:
Studies of the diagnostic criteria of atypical depression have recently increased. In one such study, Parker and others sampled individuals with major depressive disorder (MDD) (1) and, after finding weak correlations and associations among only some atypical symptoms, reported weak support for DSM-IV-TR atypical features criteria (2). (According to these criteria, an individual must present a bipolar or MDD major depressive episode or dysthymic disorder, always including mood reactivity plus at least 2 of the following: increased weight or appetite, hypersomnia, significant energy loss, and long-standing sensitivity to interpersonal rejection, but no melancholic or catatonic features.) In another study, Posternak and Zimmerman found no correlations among atypical symptoms in subjects who mainly suffered from MDD (3). An important limitation of these studies is that conclusions are based only on subjects with MDD, while in the DSM-IV-TR, atypical features can occur in individuals with either depressive or bipolar disorders (BDs). Atypical depression may be different in BD, compared with MDD. Studies by Benazzi (4) and Angst and others (5) found atypical features to be much more common in BD II than in MDD, which accords with the official DSM-IV-TR statement (p 421). In the Benazzi study of consecutively presenting outpatients, atypical features were present in 53.5% of subjects with BD II (n = 241) and in 23.7% of subjects with MDD (n = 164) (z = 5.9, P = 0.0000) (4). These 2 studies have an important difference from the Parker and others (1) and Posternak and Zimmerman (3) studies: they include mixed samples (that is, BD II plus MDD). Benazzi found significant associations among atypical symptoms (4). However, while most atypical symptoms were significantly associated in Benazzi’s BD II sample, only a few were significantly associated in his MDD sample. This suggests that atypical depression may differ in depressive and bipolar disorders (6). Angst and others also found significant associations among atypical symptoms (5), but in the Angst and others study, atypical depression was not studied separately in the BD II and MDD sample (which were combined in the analyses). Parker and others (1), Posternak and Zimmerman (3), and Angst and others (5) concluded that mood reactivity should not have the priority it has in DSM-IV-TR (according to which it must always be present). Benazzi (4) came to the same conclusion, but only for the MDD sample. In the BD II sample, mood reactivity was significantly associated with atypical symptoms, and depression patients with mood reactivity had significantly more atypical symptoms than did depression patients without mood reactivity. These findings support the inclusion of mood reactivity among the atypical features in BD II but not in MDD. Consequently, atypical depression should probably be studied independently in MDD and in BDs. Parker and others stated that hypothesizing a different response to antidepressants to support the diagnostic validity of atypical features (currently its main validator) is an unusual approach (1). Family history is a more important diagnostic validator (6,7). It has been shown that atypical features are strongly associated with a positive family history of BD (8)—a finding further supporting the distinction between atypical depression in MDD and in BD. Further studies are required to find a new definition of atypical depression, beyond that offered in the DSM-IV-TR.
References
1. Parker G, Roy K, Mitchell P, Wilhelm K, Malhi G, Hadzi-Pavlovic D. Atypical depression: a reappraisal. Am J Psychiatry 2002;159:1470–9.
2. American Psychiatric Association. Diagnostic and statistical manual of mental disorders. 4th ed. Text revision. Washington (DC): American Psychiatric Association; 2000.
3. Posternak MA, Zimmerman M. Partial validation of the atypical features subtype of major depressive disorder. Arch Gen Psychiatry 2002;59:70–6.
4. Benazzi F. Should mood reactivity be included in the DSM-IV atypical features specifier? Eur Arch Psychiatry Clin Neurosci 2002;252:135–40.
5. Angst J, Gamma A, Sellaro R, Zhang H, Merikangas K. Towards validation of atypical depression in the community: results of the Zurich cohort study. J Affect Disord 2002;72:125–38.
6. Akiskal HS. Classification, diagnosis and boundaries of bipolar disorders: a review. In: Maj M, Akiskal HS, Lopez-Ibor JJ, Sartorius N, editors. Bipolar disorder. Chichester (UK): John Wiley and Sons; 2002. p 1–52.
7. Robins E, Guze SB. Establishment of diagnostic validity in psychiatric illness: its application to schizophrenia. Am J Psychiatry 1970;126: 983–7.
8. Benazzi F. Atypical depression and its relation to bipolar spectrum. In: Marneros A, Goodwin FK, editors. Mixed states. Cambridge (UK): Cambridge University Press. Forthcoming.
Franco Benazzi, MD
Forli, Italy
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