16 06 2015
Diabetes (DM) affects up to 14% of Western population. 25% of women and 16% of men will have depression during their life time. Depression and diabetes often co occur . The link between DM and depression is bidirectional. It is also known that both disorders contribute to an increased risk for vascular complications.
A Danish study ( by researchers from Seattle and Copenhagen) using national cohort of 2.4 million people has done just this.All living Danish citizens 50 years or older who were free of dementia at January 2007 were followed up until December, 2013 .Danish psychiatric central register identified individuals with a diagnosis of depression or who have been prescribed with antidepressants. National diabetes register identified those diagnosed with DM .
19 % had a diagnosis of depression. 9 % received a diagnosis of DM, and 4% had comorbid depression and DM.The mean age at the initial diagnosis of DM was 63 years. Mean age at the initial diagnosis of depression was 59 years. 2.4% developed dementia, of this, 26% had depression alone,11% had DM alone, and 7% had comorbid depression and DM.
Depression alone, contributed 83% greater risk of dementia. DM alone was associated with a 20% greater risk for all-cause dementia. Depression and DM the risk was higher: a 117% greater risk. This combined effect is more pronounced in younger people. The combined effect of these two illness exposures on all-cause dementia risk was larger than the sum of the 2 individual diseases.
One limitation is the lack of information on possible confounders such as health-risk behaviors ( smoking, obesity, and sedentary lifestyle) .These can well be mediators of the association.
Comments: Depression alone is associated with the highest relative risk for all-cause dementia. Individuals with depression and DM need to consider engaging in neuro protective activities. Physical activity is increasingly well established as an effective strategy. It have anti-inflammatory effects and it promotes neurovascular health.
Summary of the article:
Katon W, Pedersen HS, Ribe AR, Fenger-Grøn M, Davydow D, Waldorff FB, Vestergaard M.
JAMA Psychiatry. 2015 Jun 1;72(6):612-9