Diabetic Retinopathy Appears Linked to Depression

Laird Harrison

June 02, 2020

People with diabetic retinopathy experience depression at higher rates than the general population, but the rate decreases at the most severe stage of the disease, an analysis of a large database shows.

Although the study did not establish cause and effect, it alerts clinicians to explore the ways that the emotional wellness of a patient might be intertwined with eye disease, said Daniel Olson, MD, from the University of North Carolina in Chapel Hill.

"I believe in treating the whole patient, not just the eyeball," he told Medscape Medical News.

Olson became interested in the mental health of patients with diabetic retinopathy when he noticed their reactions during conversations about the course of the disease. "You see the anxiety and sadness building up in these patients," he said.

Previous studies have established an association between the eye disease and depression and anxiety. But the number of patients in these studies was not large enough to look at the association between mental health and some key subgroups.

To fill this gap, Olson and his colleagues analyzed a database of 95,575 people 18 years and older with eye exams on record at the Carolina Data Warehouse, a repository of all patients seen in the University of North Carolina system.

The team identified all patients with diagnoses of diabetic retinopathy, anxiety, depression, or some combination of these diseases, between July 2008 and July 2018 using International Classification of Diseases (ICD) codes. In the study cohort, 57.1% of the patients were women, 23.5% had diabetes mellitus, and 4.5% had diabetic retinopathy.

Of those without diabetic retinopathy, 18.7% had anxiety and 20.4% had depression, which is consistent with rates in the general population, Olson reported during his virtual presentation at the Association for Research in Vision and Ophthalmology 2020 Annual Meeting.

Among those who had a diagnosis of diabetic retinopathy, 21.5% had anxiety and 33.0% had depression. The rate of depression was significantly higher in those with diabetic retinopathy than in the general population, but the difference in the rate of anxiety was not significant.

This study is retrospective and does not provide a causal link between diabetic retinopathy and depression or anxiety, Olson acknowledged. It's possible that people become depressed when they are diagnosed with an eye disease, or conversely that depressed people don't take good care of their health, so their diabetes worsens, which leads to diabetic retinopathy.

To see if disease severity is associated with these mood disorders, the researchers looked at disease subsets: mild, moderate, and severe nonproliferative diabetic retinopathy, and proliferative diabetic retinopathy.

The risk for depression was 98% higher in patients with severe nonproliferative disease than in those without diabetic retinopathy. However, risk for depression was just 41% higher in patients who had progressed to proliferative disease.

Table. Depression and Diabetic Retinopathy Stages
Subset of Diabetic Retinopathy Odd Ratio for Depression Confidence Interval
Mild nonproliferative 1.840 1.585–2.136
Moderate nonproliferative 1.452 1.128–1.870
Severe nonproliferative 1.984 1.281–3.074
Proliferative 1.410 1.249–1.591

A similar trend emerged for anxiety; the risk was significantly elevated only in patients with mild diabetic retinopathy.

Olson offered two possible explanations for the decline in depression and anxiety seen in patients in the most advanced stage of their disease.

First, patients might struggle to improve their exercise and diet without seeing results in the early stages of the disease. Then, once they advance to the proliferative stage and begin receiving treatment, they might realize that the treatments are not as bad as they feared. "They can calm down and not be as anxious or depressed," he said.

Second, patients with poor access to healthcare might not get treatment for diabetic retinopathy until it becomes proliferative and starts to affect their vision. Even if they are depressed, they might not see a primary care doctor, so their depression would not be documented in the database.

But such possibilities are speculative because the study does not show causation, cautioned Rahul Khurana, MD, assistant clinical professor of ophthalmology at the University of California, San Francisco.

"It's an interesting question to explore, but I'm not sure how we put it in the clinic," Khurana told Medscape Medical News.

For now, the work has already influenced Olson's interactions with his patients. He works closely with his patients' primary care physicians, and he listens more carefully.

"Rather than rattling off a list of things to do, which can be overwhelming to patients, I talk to patients about real ways they control the disease, and listen to their concerns so I can put them at ease about the course of the illness," he explained.

The study also showed that younger patients are more likely to experience anxiety than older patients, and men are more likely to experience depression than women.

"One reason for this may be that men are more visual creatures and the prospect of losing vision weighs more heavily on them," Olson said.

He said he would like to take the research further, following patients treated for both diabetic retinopathy and depression to see if depression treatment affects their retinopathy.

He has also found a similar association between mental health and age-related macular degeneration, and is exploring whether the number of injections a patient receives has any effect on mental health.

Association for Research in Vision and Ophthalmology (ARVO) 2020 Annual Meeting.

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