Late-onset depression may foreshadow Parkinson’s diagnosis
Study also links depression to Lewy body dementia
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- Late-onset depression may be an early sign of Parkinson's or Lewy body dementia.
- Depression rates are significantly higher years before diagnosis.
- Clinicians should screen for depression and monitor late-onset depression.
Depression that starts later in life could be an early clinical manifestation of Parkinson’s disease and the related condition dementia with Lewy bodies (DLB), according to a study, which found that people who were diagnosed with either of these conditions had significantly higher rates of incident depression than patients with other chronic diseases.
This increased risk was detectable as many as eight years before a formal diagnosis and persisted for several years afterward, suggesting that late-life depression may serve as an early warning sign of underlying neurodegenerative changes.
“Following a diagnosis of [Parkinson’s] or [DLB], the persistent higher incidence of depression highlights the need for heightened clinical awareness and systematic screening for depressive symptoms in these patients,” the researchers wrote.
The study, “Depression preceding and following the diagnosis of Parkinson’s disease and Lewy body dementia,” was published in General Psychiatry.
Retrospective study maps depression rates
A hallmark feature of Parkinson’s and DLB is the formation of toxic protein clumps in brain cells, called Lewy bodies, which are thought to contribute to neuronal dysfunction and death. However, in Parkinson’s, motor symptoms typically precede cognitive symptoms, whereas in DLB, cognitive problems appear first.
Depression affects up to 40% of these patients and is thought to be associated with the progressive neurological changes that occur in these conditions. “However, studies examining the rate of incident depression in the period preceding and following the diagnosis of [Parkinson’s] and [DLB] are lacking,” the researchers wrote.
To learn more, researchers conducted a retrospective study of data from people diagnosed with Parkinson’s or DLB from 2007 to 2019, as recorded in Danish national health registers. They identified a total of 17,711 patients, 14,636 with Parkinson’s and 3,075 with DLB, with 60.1% being men and a median age of 75.
Researchers compared these patients with age- and sex-matched people diagnosed with other long-term conditions affecting the joints (rheumatoid arthritis), kidneys (chronic kidney disease), and bones (osteoporosis).
In the 10 years before diagnosis, 13.1% of those with Parkinson’s and 16.9% of those with DLB developed depression during a median follow-up of 6.7 years. For a similar follow-up period, depression was diagnosed in up to 7.8% of those with other chronic conditions.
The risk of new onset depression was consistently higher in Parkinson’s and DLB patients, from seven to eight years before diagnosis to five years after diagnosis, and peaking in the three years before diagnosis. From three years before to three years after diagnosis, the rates of depression were significantly higher in DBL patients than in those with Parkinson’s.
The researchers wrote that by comparing the rates of depression in Parkinson’s and DLB patients to those in people with other chronic conditions, the results “support that depression … is a key manifestation of these diseases and is likely to be related to the underlying neurodegenerative processes,” rather than a psychological reaction to worsening health.
They noted these results do not mean that everyone with depression will develop Parkinson’s or DLB, but recommend closer monitoring when depression appears for the first time in older people.
