The potential role of scales in discriminating unipolar and bipolar depression

O papel potencial de escalas para discriminar depressão unipolar da bipolar

DEAR EDITOR,

We would like to congratulate the authors of the paper entitled “Predicting response to treatment and discriminating bipolar and depression symptoms using Hamilton Depression Rating Scale”¹. The article raises several interesting questions involving the use of scales for the measurement of depressive symptoms among unipolar and bipolar patients. Specifically, we were particularly interested in the possibility of a potential role the Hamilton Depression Rating Scale (HAM-D) and the Montgomery-Asberg Depression Rating Scale (MADRS) could have in differentiating unipolar and bipolar depression.

There are, however, some conceptual issues worth emphasizing. First, both the MADRS and the HAM-D were not originally designed to improve diagnostic accuracy but, as the authors themselves emphasize, to measure changes in depressive symptoms overtime among patients already diagnosed with mood disorders, hence their widespread use in clinical trials^2,3. Therefore, hypothesizing that they could have some usefulness in distinguishing unipolar from bipolar depression should be seen with reservations. In fact, it seems the authors goal was actually to assess whether or not the HAM-D and/or the MADRS could identify different patterns of progression/change in mood among unipolar versus bipolar patients, instead of sorting out unipolar versus bipolar patients. Second, despite some previous conflicting results in that regard^4,5, we wonder if the authors considered performing a factorial analysis (or other type of statistical approach) aiming at assessing the possible role of specific clusters of symptoms (maybe utilizing the scale results at baseline) in discriminating bipolar from unipolar depression.

Nevertheless, the above-mentioned points do not decrease the merit of this study. As the concept of bipolar spectrum has been expanded, the borders between unipolar and bipolar depression have become progressively more blurred, and there is an urgent need for instruments aiming at helping in the differential diagnosis between unipolar and bipolar depression, specially among patients with no previous formal diagnosis of bipolar disorder.

REFERENCES

• ¹
  Carneiro AM, Cavalcanti A, Carvalho LF, Moreno RA. Predicting response to treatment and discriminating bipolar and depression symptoms using Hamilton Depression Rating Scale. J Bras Psiquiatr. 2017;66(3):125-30.
• ²
  Montgomery SA, Smeyatsky N, de Ruiter M, Montgomery DB. Profiles of antidepressant activity with the Montgomery-Asberg Depression Rating Scale. Acta Psychiatr Scand Suppl. 1985;320:38-42.
• ³
  Worboys M. The Hamilton Rating Scale for Depression: The making of a “gold standard” and the unmaking of a chronic illness, 1960-1980. Chronic Illn. 2013;9(3):202-19.
• ⁴
  Benazzi F. The Montgomery Asberg Depression Rating Scale in bipolar II and unipolar out-patients: a 405-patient case study. Psychiatry Clin Neurosci. 1999;53(3):429-31.
• ⁵
  Perlis RH, Brown E, Baker RW, Nierenberg AA. Clinical features of bipolar depression versus major depressive disorder in large multicenter trials. Am J Psychiatry. 2006;163(2):225-31.

Publication Dates

• Publication in this collection
  Oct-Dec 2018

History

• Received
  4 July 2018
• Accepted
  5 Aug 2018