To the Editor: In their article published in the February 2009 issue of the Journal, Bruce I. Turetsky, M.D., and Paul J. Moberg, Ph.D., noted an odor-specific detection deficit in schizophrenia that may implicate abnormal intracellular cAMP signaling (1). The patients were able to normally detect citralva, a strong stimulator of adenyl cyclase, but not lyral, a weak stimulator. Drs. Turetsky and Moberg failed to note prior work that conflicts with the conclusions drawn from their results.
Impaired odor detection of other substances, including iso-amyl acetate (2), dimethyl disulfide (3), and geraniol (4), has been demonstrated in schizophrenia. Individuals with schizophrenia have an impaired ability to detect geraniol, which is a strong adenyl cyclase stimulator similar to citralva. Citralva placed fourth and lyral placed 42nd in the ranking of adenyl cyclase response in tests of 44 odorants, and geraniol was the tenth most potent stimulator (5). In a study of odorant-stimulated electro-olfactogram response, citralva ranked fifth out of 36 odorants, lyral was ranked 21st, and geraniol was ranked eighth (6). Geraniol clearly resembles citralva in its ability to stimulate adenyl cyclase but differs in that geraniol cannot be detected normally by schizophrenia patients.
It seems that odor detection deficits in schizophrenia may have a more complex explanation than the specific signal transduction mechanism cited.
1.Turetsky BI, Moberg PJ: An odor-specific threshold deficit implicates abnormal cellular cyclic AMP signaling in schizophrenia. Am J Psychiatry 2009; 166:226–2332.Sirota P, Ben-David I, Luca-Haimovici K, Zohar J, Gross-Isseroff R: Neuroleptics, olfactory sensitivity and schizophrenia. Biol Psychiatry 1995; 37:6643.Rupp CI, Fleischhacker WW, Kemmler G, Oberbauer H, Scholtz AW, Wanko C, Hinterbauer H: Various bilateral olfactory deficits in male patients with schizophrenia. Schizophr Bull 2005; 31:155–1654.Serby M, Larson P, Kalkstein D: Olfactory sense in psychoses. Biol Psychiatry 1990; 28:8305.Sklar PB, Anholt RR, Snyder SH: The odorant-sensitive adenylate cyclase of olfactory receptor cells. J Biol Chem 1986; 261:15538–155436.Lowe G, Nakamura T, Gold GH: Adenylate cyclase mediates olfactory transduction for a wide variety of odorants. Proc Natl Acad Sci USA 1989; 86:5641–5645
The author reports no competing interests.
This letter (doi: 10.1176/appi.ajp.2009.09020268) was accepted for publication in March 2009.