Depression: Early Symptom of Parkinson's?

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It has long been known that people with Parkinson's often suffer from depression. But they are not necessarily the result of the serious illness - the persistent depression can apparently also be a harbinger of the illness.

Shaky stiff muscles, freezing movements and rigid facial expressions - Parkinson's is a great burden for those affected. It is not yet clear why some people get it. The extent to which depression plays a role in this context was examined by Peter Nordström and his colleagues from Umeå University in Sweden.

Depression symptom or risk factor

To do this, the team analyzed the data of all Swedish citizens aged 50 and over. The diagnosis of depression was made in just under 140,700. To check whether these patients develop Parkinson's more frequently than those who are not depressed, the researchers compared three mentally healthy citizens of the same age and sex to each.

In fact, the researchers found a link between depression and later-onset Parkinson's disease. Around one percent of the formerly depressed subjects fell ill with Parkinson's. In the three times larger control group, however, Parkinson's only occurred half as often. "So depression could be a very early symptom of Parkinson's," reports Helena Gustafsson, co-author of the study. It is also possible that the mental illness increases the risk of Parkinson's.

Common Genetic Root?

It is conceivable that depression and Parkinson's often occur in combination because they have a common genetic root. But the researchers were able to show that this is apparently not the case using a study of siblings: If one fell ill with depression, the other was not more likely to develop Parkinson's - and vice versa. "If the diseases were independent of each other and were caused solely by the same genetic constellation, that would have to be exactly the case," says study leader Nordström. So there must be a direct connection between the occurrence of depression and Parkinson's disease.

The scientists were also able to rule out that other factors such as brain injuries or alcohol abuse, which can be associated with depression, are responsible for Parkinson's: the connection between depression and Parkinson's remained after they had excluded the relevant parameters.

The risk increases with the severity of the depression

Parkinson's disease is particularly common in people who have previously suffered from particularly severe depression. For example, patients who had to be treated as an inpatient due to their mental problems were 3.5 times more likely to develop Parkinson's than those for whom outpatient therapy was sufficient.

The time lag to the previous depressive history also proved to be decisive for the Parkinson's risk: In the year after the low mood, those affected developed Parkinson's around three times more often than those who were mentally stable. 15 to 25 years after the depression, the risk dropped significantly - but it was still twice as high as in the mentally healthy.

Cell death in the brain

Over 250,000 people in Germany suffer from Parkinson's. The cause is the progressive death of dopamine-producing cells in the brain and the resulting lack of dopamine. Most people are between 50 and 60 years old at the time of diagnosis - only about ten percent of those affected are younger than 40. Modern drugs often enable a largely symptom-free life for years - but the disease has not yet been curable.

Sources:

Gustafsson H. et al .: Depression and subsequent risk of Parkinson disease. Neurology. doi: 10.1212 / WNL.0000000000001684

Umeå University press release from May 21, 215

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