a1 Department of Psychiatry, Roy J. and Lucille A. Carver College of Medicine, University of Iowa Hospitals and Clinics, Iowa City, IA, USA
a2 Department of Psychiatry and Human Behavior, The Warren Alpert Medical School of Brown University, Providence, RI, USA
a3 Department of Psychiatry, Columbia University College of Physicians and Surgeons, New York, NY, USA
a4 Department of Psychiatry, University of California, San Diego, CA, USA
Background The authors used results from a 20-year, high-intensity follow-up to measure the influence of ageing, and of age at onset, on the long-term persistence of symptoms in major depressive disorder (MDD).
Method Subjects who completed a 20-year series of semi-annual and then annual assessments with a stable diagnosis of MDD or schizo-affective disorder other than mainly schizophrenic (n=220) were divided according to their ages at intake into youngest (18–29 years), middle (30–44 years) and oldest (>45 years) groups. Depressive morbidity was quantified as the proportion of weeks spent in major depressive or schizo-affective episodes. General linear models then tested for effects of time and time×group interactions on these measures. Regression analyses compared the influence of age of onset and of current age.
Results Analyses revealed no significant time or group×time effects on the proportions of weeks in major depressive episodes in any of the three age groups. Earlier ages of onset were associated with greater symptom persistence, particularly in the youngest group. The proportions of weeks ill showed intra-individual stability over time that was most evident in the oldest group.
Conclusions These results indicate that the persistence of depressive symptoms in MDD does not change as individuals move from their third to their fifth decade, from their fourth to their sixth decade, or from their sixth to their eighth decade. An early age of onset, rather than youth per se, is associated with greater morbidity over two decades.
(Received September 19 2008)
(Revised January 06 2009)
(Accepted January 11 2009)
(Online publication March 19 2009)
c1 Address for correspondence: W. Coryell, M.D., Roy J. and Lucille A. Carver College of Medicine, University of Iowa Hospitals and Clinics, 200 Hawkins Drive, Iowa City, Iowa 52242, USA. (Email: firstname.lastname@example.org)