just happened to have these handy:
LEVODOPA STATS
Young Onset and Levodopa Side Effects
Quinn N, Movement Disorders, Vol 2, No 2, pp. 73-91, 1987 showed the following regarding young onset (under 40) and l-dopa :
20% chance of dyskinesias within one month on l-dopa
55% chance within one year
74% chance within four years (at 2 year mark, 50% of dyskinesias classified as “often causing functional disability”)
100% chance within six years
and
10% chance of on/off fluctuations within one month on l-dopa
38% chance within one year
50% chance within 2-3 years
96% chance within 6 years
Wagner ML, Complications of disease and therapy: a comparison of younger and older patients with Parkinson's disease. Ann Clin Lab Sci. 1996 Sep-Oct;26(5):389-95:
“165 patient records were divided according to patient age into two groups ("younger," 41 to 64, and "elderly," > or = 65 years) and reviewed for the incidence of dyskinesias, fluctuations, freezing, psychosis, … Younger patients had a greater incidence of chorea (75.8 percent vs 49.5 percent), dystonia (82.3 percent vs 49.0 percent), fluctuations (90.1 percent vs 68.1 percent)…
[unfortunately, this abstract does not provide the length of time participants had been on l-dopa]
Shrag A. Young-onset Parkinson's disease revisited--clinical features, natural history, and mortality. Mov Disord. 1998 Nov;13(6):885-94:
“After a disease duration of 10 years or less, only 5% of patients were experiencing falls and 30% freezing, but all patients had developed L-dopa-related fluctuations and dyskinesias.”
Any Age Onset and Levodopa Side Effects
Friedman A. Levodopa-induced dyskinesia: clinical observations, Journal of Neurology, 1985;232(1):29-31:
“Levodopa-induced dyskinesia was observed in 92 patients (64%)…The age at onset of the disease of patients with dyskinesia was significantly different from the age at onset of those without dyskinesia, the means being 54.8 and 68.9 years respectively…The influence of the duration of levodopa treatment on the manifestation of dyskinesia could not be confirmed because this side-effect usually appeared during the first year of treatment.”
[again, unfortunately, no timeframe in the abstract]
Chase, TN. Drugs 1998;55 Suppl 1:1-9
Most common are the motor response complications that appear within a few years of treatment initiation and ultimately affect most parkinsonian patients. These progressively disabling complications include response fluctuations and abnormal involuntary movements.
Kumar N, Movement Disorders, Vol 20, No 3, pp 342-366, 2005 found that within 5 years, onset at age:
40-49 - 40% chance of developing dyskinesias
50-59 - 53% chance
60-69 - 26% chance
70-79 - 16% chance
80-89 - 14% chance
In the 2004 article entitled “Levodopa in the Treatment of PD: Current Controversies,” a team of researchers led by Warren Olanow states that motor fluctuations occur in approximately 50 - 80% of PD patients who have received l-dopa for more than 5 to 10 years, which is a bit ambiguous.
In May 2005, Olanow made a presentation as part of a Continuing Medical Education event called “Spotlight on Parkinson’s” in which he was considerably less ambiguous, saying “motor complications affect approximately 80% of patients treated with levodopa for > 5 years” and “develop in approximately 100% of young-onset PD patients.”’
Dr. Kapil Sethi cites a 1997 study by John Nutt published in the Annals of Neurology (for which i could not figure out how to gain access) in his presentation at the same Continuing Medical Education event saying that “a majority of patients develop motor fluctuations even during the first year of therapy,” and, from the DATATOP trial, “wearing-off has been reported in 50% of patient within two years of L-dopa therapy.”
At each juncture, it is as if these side effects have only recently emerged:
1977
with respect to long-term levodopa therapy, two problems "...have emerged as frequent and serious, an insidious and progressive loss of benefit and the appearance of progessively more severe fluctuations in disability....Discovery of the exact causes for loss of benefit may provide a rational basis for new therapy."
1989
"Management of Parkinson's disease has in recent years become more difficult than in the early years of levodopa therapy, due to the loss of benefit and the many late problems, especially fluctuations in disability. New therapeutic strategies are therefore needed in the treatment of patients."
2005
"...motor complications of chronic levodopa therapy have emerged as a major limitation of this otherwise effective therapy"
Almost 40 years ago they “have emerged.”
That is Warren Olanow calling levodopa "otherwise effective.” I guess he must be referring to the 50% of patients who get a whole two years and possibly slightly more of "otherwise effective"ness," but not much, because by the 5 year mark, maximum 20% will still be experiencing "otherwise effective"ness and for some reason, 5 years is as far out as he goes (not very reassuring for us 42 year-olds.)