Brief report MRI exploration of pineal volume in bipolar disorder Samuel Sarrazin a , Bruno Etain a, b, c , François-Eric Vederine a, b , Marc-Antoine d'Albis a, b , Nora Hamdani a, b , Claire Daban a, b , Marine Delavest d , Jean-Pierre Lépine c, d , Marion Leboyer a, b, c , Jean-François Mangin e , Cyril Poupon e , Josselin Houenou a, b, c, e, ⁎ a AP-HP, University Paris-East, Department of Psychiatry, Henri Mondor-Albert Chenevier Hospitals, Créteil, F-94010, France b INSERM, U955 Unit, IMRB, Department of Medical Genetics, Psychiatry Genetics, Créteil, F-94010, France c FondaMental Foundation, Créteil, F-94010, France d AP-HP, Department of Psychiatry, Lariboisiere Fernand Widal Hospital, INSERM U 705 CNRS UMR 8206, Paris Diderot University, Paris, France e Neurospin, CEA Saclay, LNAO, Gif-Sur-Yvette, France article info abstract Article history: Received 31 March 2011 Received in revised form 31 May 2011 Accepted 1 June 2011 Available online 22 June 2011 Background: Circadian rhythm instability and abnormalities of melatonin secretion are considered as trait markers of bipolar disorder. Melatonin is secreted by the pineal gland. We investigated pineal volume in patients with bipolar disorder, and expected to observe smaller than normal pineal glands in cases of bipolar disorder. Methods: The primary outcome was the total pineal volume measured for each pineal gland with T1 MRI sequence. Twenty patients with bipolar I and II disorder and twenty controls were recruited. Pineal glands with large cysts (type 3) were excluded. Results: After exclusion of individuals with type 3 cysts, 32 subjects were analyzed for total pineal volume (16 patients with bipolar disorder and 16 controls). Total pineal volume did not differ significantly between patients (total pineal volume = 115+/-54.3 mm 3 ) and controls (total pineal volume = 110+/-40.5 mm 3 ). Conclusions: Contrary to our hypothesis, no difference in total pineal volume between patients with bipolar disorder and healthy subjects was observed. These results indicate that the putative dysfunction of the pineal gland in bipolar disorder could be not directly related to an abnormal volume of the pineal gland. © 2011 Elsevier B.V. All rights reserved. Keywords: Bipolar disorder MRI Pineal gland Melatonin Circadian rhythm 1. Introduction Bipolar disorder (BD) is a complex psychiatric disorder of unknown aetiology. There is growing interest in an altered rhythmicity of several physiological functions in euthymic patients with BD (Dallaspezia and Benedetti, 2009). In particular, circadian rhythm instability is one of the best candidate brain function trait markers in BD. Insomnia, fragmentation of the sleep/wake rhythm, night-to-night sleep variability, longer sleep onset latency, and higher REM density have all been reported in euthymic patients with BD (Harvey, 2008). Abnormalities of melatonin secretion, and in particular hypersensitivity to light (nocturnal bright light suppression of melatonin), have been proposed as a heritable trait marker of BD (Hallam et al., 2006). The decrease in nocturnal plasma melatonin concentrations in response to light in euthymic drug-free patients is double than in healthy controls (Nathan et al., 1999). During euthymic phases, both lower than normal melatonin concentrations, and later time of peak of secretion during night, have been described in patients with bipolar I disorder (Nurnberger et al., 2000). Overnight reduced serum melatonin concentration is independent of the state of illness, suggesting that decreased serum melatonin is a trait marker of BD (Kennedy et al., 1996). Finally the efficacy of mood Journal of Affective Disorders 135 (2011) 377–379 ⁎ Corresponding author at: INSERM, U955, IMRB, Department of Medical Genetics, Psychiatry Genetics, Creteil, France. Tel.: +33 1 49 81 30 51; fax: + 33 1 49 81 30 59. E-mail address: josselin.houenou@inserm.fr (J. Houenou). 0165-0327/$ – see front matter © 2011 Elsevier B.V. All rights reserved. doi:10.1016/j.jad.2011.06.001 Contents lists available at ScienceDirect Journal of Affective Disorders journal homepage: www.elsevier.com/locate/jad