Reacción a "Untreated sleep apnoea is associated with an increased risk of Parkinson's disease, according to data from US war veterans"

Sleep apnoea or obstructive sleep apnoea (OSA) is a condition caused by the relaxation of the muscles of the tongue and pharynx during sleep, which ends up obstructing the airways. The mechanical obstruction results in respiratory arrest (apnoea) lasting several tens of seconds (most commonly between 10 and 40 seconds), leading to a decrease in blood oxygen and an increase in carbon dioxide (CO₂). This occurs up to 30 times per hour in severe cases and, in addition to fragmenting sleep, increases the risk of high blood pressure and heart disease and the incidence of cognitive disorders. This condition can be improved if patients sleep with a mask that delivers positive pressure air to the mouth and nose to overcome the obstruction. This treatment is called CPAP, Continuous Positive Air Pressure. Many patients adapt well to the mask, but others cannot tolerate it and stop using it. Naturally, adherence to treatment is essential for its beneficial effect.      

The study is an epidemiological study (descriptive without going into mechanisms) on the relationship between the incidence of Parkinson's disease (PD) in patients with OSA in a large population (more than 11 million) of US military veterans over the age of 40 (about 10% are women). The patients were studied between 1999 and 2022, with an average follow-up of five years. The study had two main objectives: i) To determine whether the incidence of PD is higher in patients suffering from OSA; ii) To see whether CPAP treatment reduces the incidence of PD. There were previous data on the relationship between OSA and PD, but with fewer patients and inconclusive results. The pathogenesis of the association between OSA and PD is unknown, but hypoxaemia (lack of oxygen in the blood), excess CO₂, together with the inflammatory and cardiovascular alterations caused by OSA, can damage nerve cells and facilitate the onset of PD.   

The study's answer is clearly positive in both cases. The risk of developing PD is clearly higher in patients with OSA, and this risk is even more evident in women. The use of CPAP prevents the onset of PD in patients with OSA, especially if it is applied in the early stages of PD. In other words, the study clearly shows an association suggested by previous studies but not proven. From now on, OSA will have to be treated seriously if the risk of PD (and other neurological disorders) is to be reduced.  

I believe that a very important limitation (which the authors point out) is that there is no objective record of patient adherence to CPAP treatment. I believe that the data are applicable to other populations, but this will naturally have to be demonstrated.   

There are several previous studies associating OSA and PD, but the data were inconclusive. I believe that the current study is technically well done (patient classification, data management and statistical analysis), the number of patients is very high, and the analysis has taken into account possible confounding factors (obesity and cardiovascular or psychiatric comorbidities, among others).   

As for the influence of sleep disorders on our health, sleep is a factor in overall health and must be taken care of at all ages.