Dose gaps depend on several factors – partly how long a particular medicine remains active in the body and brain, and partly how much the disease has affected the nerve cells in the brain. Dopamine is stored in the nerve endings in the brain and L-dopa medication replenishes these stores, but this capacity decreases as a result of the disease process. By combining different types of medication, increasing the number of doses and the strength of each dose, it is possible to compensate for and counteract the gradual worsening of symptoms. The dosage of medication is not the same in the early years as it is after around 5–10 years, or after 25 years; it usually increases over time.
If, despite adjustments to medication and various combinations of medicines, it is not possible to achieve good function, it may be appropriate to consider so-called advanced treatments.
One way of assessing whether the time is right and appropriate for potential advanced treatment is to apply the 5–2–1 method. This involves taking anti-Parkinson’s medication on at least 5 occasions, and despite this, experiencing at least 2 hours of ‘off’ symptoms (symptoms between doses), as well as further signs of disease progression, such as hyperkinesia, for at least 1 hour per day.
It is then recommended that the patient be referred to the regional centres for advanced treatments for an assessment of whether they meet the criteria for potential advanced treatment.