A recent study by researchers from NIMHANS has found an earlier onset of Parkinson’s disease (PD) in Indians compared to people living with this movement disorder in other countries.
This difference extends to almost a decade, revealed the study that has been published in ‘Parkinsonism and Related Disorders’ last week.
NIMHANS is observing movement disorders awareness week from November 23.
Pramod Kumar Pal, Professor, Department of Neurology at NIMHANS, who is the corresponding author of the study, told The Hindu that a manual chart review was carried out for 2,035 patients, including 550 women, with PD who had been evaluated at the Neurology OPD and Movement Disorder Clinic at NIMHANS.
“An exploration of recent studies providing the average age at onset (AAO) of PD revealed that our cohort had an earlier onset of illness in comparison to most other countries. While the mean AAO in our cohort was observed to be 51.03 ± 11.32 years (with an average age at evaluation of 55.50 ± 10.87 years, and duration of illness of 4.46 ± 4.11 years.), we have also evaluated patients aged around 45 for PD,” he said.
Other countries
“This difference extends to almost a decade when compared to studies from Europe (mean AAO: 60.07 years) and North America (mean AAO: 58.2). Interestingly, our cohort had a much lower AAO even in comparison to other Asian countries (mean AAO: 58.85). The only country with an AAO significantly lower than India was Colombia (mean AAO: 46.26). Another interesting observation from this exploration is the earlier AAO noted in the lower latitudes,” Dr. Pal said.
PD was always considered to be a disease of the elderly with a five to ten-fold increase beyond the sixth decade, an AAO of approximately 60 years, and age itself considered to be a risk factor.
However, this simple concept of PD being a geriatric illness has been challenged over the past few decades by several studies that have consistently demonstrated an early onset of PD with definitive variability, especially when different geographical regions are compared, the doctor said.
Younger AAO in women
A comparison of male and female patients revealed that female patients had a younger AAO. Additionally, although tremors were the most prevalent symptom at onset in both genders, rigidity was significantly more prevalent in women, the study found.
While a majority had onset of symptoms on the right side (55.92%) and tremors were the most prevalent symptom at onset, family history of tremors or Parkinsonism was reported by 6.19%.
“A comparison of patients with early and late AAO revealed that a higher prevalence was observed in late onset PD. A higher prevalence of rigidity was observed in early onset PD. No differences were observed either with regard to family history or stage of progression when compared between gender or early and late onset PD,” the study pointed out.
Implications
Dr. Pal explained that the implications of an earlier onset are multi-fold and extend beyond possible phenotypic variability.
“In the present study, patients with early onset PD did not report a higher prevalence of family history. However, this may be influenced by recall bias, or lack of awareness about the presence of such symptoms in family members,” he said.
“In addition, other possible factors such as variability in environmental exposures and dietary factors also need to be evaluated. In countries with younger populations such as India, this observation of an earlier AAO has significant implications on overall prevalence of the disease and the impact on overall quality of life, caregiver, social and economic burden,” he added.
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