Dimitry Davydow, M.D., M.P.H., an associate professor of psychiatry and behavioral sciences at the University of Washington School of Medicine, and colleagues analyzed data on more than 2.4 million Danish citizens, 50 years or older, who were free of dementia from January 1, 2007, through December 31, 2013, to estimate the risk of all-cause dementia associated with DM, depression, or both. Within this population, 477,133 (19.4 percent) had been diagnosed with depression, 223,174 (9.1 percent) with DM, and 95,691 (3.9 percent) with both.
The researchers found that over the course of the study, 59,663 participants (2.4 percent) developed dementia, and of these, 6,466 (10.8 percent) had DM, 15,729 (26.4 percent) had depression, and 4,022 (6.7 percent) had both. Compared with people without depression or DM, the authors reported that DM alone was associated a 20 percent greater risk of dementia, depression alone was associated with an 83 percent greater risk, and comorbid depression and DM were associated with a 117 percent greater risk, after adjusting for such factors as age, sex, and marital status. For those under 65 years with depression and DM, the risk for dementia appeared to be even greater.
"Given that depression in patients with DM is associated with poor self-care, nonadherence to treatment regimens, and adverse psychobiological changes, this younger group with comorbid depression and DM may be vulnerable to developing dementia later in life," the authors wrote. "From a public health perspective, developing screening and interventions to improve the quality of treatment of depression and DM in this subgroup of patients could be important in reducing the risk for dementia.”
For more on the association between diabetes and mental disorders, see the Psychiatric News article “Link Seen Between Mental Disorders, Diabetes in New Study.”