Scientists pinpoint brain’s ‘early warning sign’ of Parkinson’s or dementia

Researchers have pinpointed one of the brain’s “early warning signs” of dementia and Parkinson’s disease. According to the findings, this symptom can appear eight years before diagnosis.

A new study, published in General Psychiatry, found that depression often appears before a diagnosis of Parkinson’s disease (PD) and Lewy body dementia (LBD) and continues to remain elevated for several years afterwards. As part of the research, a team analysed a study involving 17,711 people diagnosed with PD or LBD between 2007 and 2019. 

These patients were compared with people of similar age and sex who had been diagnosed with other chronic conditions, including rheumatoid arthritis, chronic kidney disease, and osteoporosis.

As reported by Science Daily, the findings revealed a distinct pattern: depression manifested more frequently and earlier in individuals who subsequently developed Parkinson’s disease or Lewy body dementia compared to those with other chronic illnesses. 

In the years preceding diagnosis, the risk of depression increased progressively, reaching its highest point in the three years before diagnosis. Even following diagnosis, patients with Parkinson’s disease or Lewy body dementia continued to experience elevated rates of depression compared to the control groups.

Crucially, this pattern could not be entirely attributed to the emotional strain of managing a chronic illness. Other long-term conditions that similarly involve disability did not demonstrate the same pronounced elevation in depression risk.

This indicates that depression may be connected to early neurodegenerative changes in the brain, rather than being solely a psychological response to deteriorating health. The results were particularly notable for Lewy body dementia, where depression rates exceeded those in Parkinson’s disease, both prior to and following diagnosis.

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Researchers observed that variations in disease progression and brain chemistry may account for this pattern. 

First author Christopher Rohde said: « Following a diagnosis of PD or LBD, the persistent higher incidence of depression highlights the need for heightened clinical awareness and systematic screening for depressive symptoms in these patients. Thus, our main conclusion-that PD/LBD are associated with a marked excess depression risk preceding and following diagnosis when compared with other chronic conditions-remains valid. »

However, the authors clarified that this doesn’t suggest everyone experiencing depression will go on to develop Parkinson’s disease or dementia. Rather, they advocate for increased awareness and more rigorous monitoring when depression emerges for the first time in elderly people.

Dementia and depression

Health bodies have also previously linked dementia and depression. The Alzheimer’s Society says: “Depression is a common problem for people with dementia.  

“It is often diagnosed when a person is in the early stage of the condition, but it can develop at any time. Some people may become depressed as a reaction to negative events or not having positive experiences to look forward to. 

“Other people may become depressed because of damage to parts of the brain involved in mood.” And Alzheimer’s Research UK adds: “The relationship between depression and dementia risk is complex because depression can also be an early symptom of dementia. 

“It’s important to remember that not everybody with depression will develop dementia, and not everybody with dementia will experience depression.” If you or someone you know is experiencing symptoms of dementia, you should speak to a GP.