Somatic and psychiatric comorbidity in the general elderly population: Results from the ZARADEMP Project Antonio Lobo-Escolar a,b,c , Pedro Saz a,c,d , Guillermo Marcos c,d,e,f , Miguel Ángel Quintanilla c,f , Antonio Campayo c,d,f , Antonio Lobo a,c,d,f, ⁎ the ZARADEMP Workgroup 1 a Department of Psychiatry, Universidad de Zaragoza, Zaragoza, Spain b Traumatology Service, Hospital Universitario Miguel Servet, Zaragoza, Spain c Instituto Aragonés de Ciencias de la Salud (I+CS), Zaragoza, Spain d Centro de Investigación Biomédica en Red de Salud Mental (CIBERSAM), Ministry of Health, Madrid, Spain e Department of Preventive Medicine, Universidad de Zaragoza, Zaragoza, Spain f Hospital Clínico Universitario, Zaragoza, Spain Received 1 June 2007; received in revised form 18 February 2008; accepted 10 March 2008 Abstract Objective: In a representative sample of the elderly popu- lation in a southern European city, we tested the hypothesis that there is an association between general somatic and general psychiatric morbidity. Methods: A stratified random sample of 4803 individuals aged ≥55 years was selected for the baseline study in the ZARADEMP Project. The elderly were assessed with standardized Spanish versions of instruments, including the Geriatric Mental State (GMS)–AGECAT. Psychiatric cases were diagnosed according to GMS–AGECAT criteria, and somatic morbidity was documented with the EURODEM Risk Factors Questionnaire. Results: General comorbidity clustered in 19.9% of the elderly when hypertension was removed from the somatic conditions category, with 33.5% of the sample remaining free from both somatic and psychiatric illnesses. General comorbid- ity was associated with age, female gender, and limited education, but did not increase systematically with age. The frequency of psychiatric illness was higher among the somatic cases than among noncases, and the frequency of somatic morbidity among the psychiatric cases was higher than among noncases. This association between somatic and psychiatric morbidity remained statistically significant after controlling for age, gender, and education [odds ratio (OR)=1.61; confidence interval (CI)=1.38–1.88]. Most somatic categories were asso- ciated with psychiatric illness, but after adjusting for demo- graphic variables and individual somatic illnesses, the association remained statistically significant only for cerebro- vascular accidents (CVAs) (OR=1.47; CI=1.09–1.98) and thyroid disease (OR=1.67; CI=1.10–2.54). Conclusion: This is the first study to document that there is a positive and statistically significant association between general somatic morbidity and general psychiatric morbidity in the (predomi- nantly) elderly population. CVAs and thyroid disease may have more weight in this association. © 2008 Elsevier Inc. All rights reserved. Keywords: Comorbidity (somatic and psychiatric); Community survey; Elderly; Prevalence; ZARADEMP Project Introduction Pioneer studies by authors such as Eastwood and Trevelyan [1] have found that psychiatric and somatic illnesses tend to “cluster” in a limited group of individuals in the general population. The first author speculated about vulnerability to illness, and research in this area was Journal of Psychosomatic Research 65 (2008) 347 – 355 ⁎ Corresponding author. Servicio de Psiquiatría, Hospital Clínico Universitario, Planta 3, Avda. San Juan Bosco, 15, 50009 Zaragoza, Spain. Tel.: +34 976 55 11 67; fax: +34 976 76 17 12. E-mail address: alobo@unizar.es (A. Lobo). 1 The following members of the ZARADEMP Workgroup are also authors of this article: C. de la Cámara, J.L. Día, A. Martín, J.A. Montañés, B. Quetglas, T. Ventura, and M. Zapata. 0022-3999/08/$ – see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.jpsychores.2008.03.002