Depression and dementia have long been linked, but a recent study shows that treating depression in a timely manner can reduce the risk of developing dementia in certain groups of patients.
More than 55 million people in the world suffer from dementia, which is a neurocognitive disorder that mainly affects older adults. There is no effective treatment for dementia, but finding ways to minimize or prevent the disease would reduce its burden.
The study was led by Jin-Tai Yu, MD, PhD, at Huashan Hospital and Shanghai Medical College of Fudan University, and Wei Cheng, PhD, at the Institute of Science and Technology for Brain-Inspired Intelligence of Fudan University in Shanghai, China. It appears in Biology and Psychiatry, published by Elsevier.
Professor Yu and Prof. Cheng used the data from the UK Biobank. This is a cohort with over 500,000 participants. The study involved more than 350,000 people, including 46.280 depressed participants. During the study, 725 depressed patients developed Alzheimer’s disease.
The results of previous studies that examined whether depression treatments such as psychotherapy and pharmacotherapy could reduce the risk of dementia were mixed, leaving the issue unresolved. Professor Yu said that older individuals seem to have different depression patterns with time. There is a possibility that intra-individual variations in symptoms could confer a different risk of developing dementia, as well as heterogeneity of effectiveness in depression treatment with regard to dementia prevention.
Researchers then classified participants into four different courses of depression to address this heterogeneity: an increasing course in which mild symptoms gradually increase; a decreasing course that begins with moderate or high-severity symptoms but decreases over time; a chronically high course characterized by persistent severe depressive symptoms; and a chronically low course characterized by mild or moderate symptoms.
The study confirm what was expect: depression increased the risk of developing dementia by 51% when compared with non-depressed participants. The degree of dementia risk was dependent on the severity of the depression. Those with chronically high or low depression, as well as those with an increasing course, were at greater risk. Participants with a decreasing course, however, did not face a higher risk.
Researchers were most interested in whether anxiety treatment could lower the risk of dementia. Researchers separated participants into depression courses and found that those who had chronically low or increasing depression experienced a lower dementia risk with treatment. However, those with chronically high levels of depression did not benefit from treatment.
He states that “in this instance, symptomatic depressive disorder increases dementia risk by 51 percent, while treatment was associate with an important reduction in this risk.”
“This shows that those suffering from late-life amxiety need to be treat promptly for depression,” said Professor Cheng. The treatment of depression in late life may not only reduce affective symptoms but also delay the onset of dementia.
Professor Cheng said that the new findings also shed light on earlier work. The discrepancy in previous studies could explained by the differences between depression courses.