Age as the Primary Risk Factor
Paget's disease of bone is overwhelmingly a condition of the aging skeleton. The single most important risk factor for developing this disorder is advancing age, with the incidence rate doubling every decade after a person reaches 50. Though it is very uncommon to be diagnosed with the classic form before age 40, studies show that by age 60, up to three percent of the population may be affected.
This pattern reflects the natural decline and changes that occur in bone metabolism over a person's lifespan. While the exact trigger for the disease remains unknown, it is thought that a combination of genetic predisposition and environmental factors culminates in the abnormal bone remodeling process that becomes more likely with advanced age.
Factors Influencing Risk Beyond Age
While age is the most significant factor, several other elements can influence an individual's susceptibility to Paget's disease. These can work in tandem with age to increase or decrease the likelihood of developing the condition.
Genetics and Family History
Family history plays a notable role in increasing risk. If you have a close relative, such as a parent or sibling, with Paget's disease, your risk is significantly higher—estimated to be up to ten times greater than the general population. Some studies have identified specific genetic mutations, particularly in the SQSTM1 gene, that are linked to the disease. These genetic links suggest that while the disease manifests later in life, the underlying susceptibility can be inherited.
Geography and Ethnicity
The prevalence of Paget's disease is not uniform across the globe, suggesting environmental factors also play a part. The disease is historically more common in certain populations of Northern European descent, including England, Scotland, central Europe, and countries settled by European immigrants, such as Australia and the United States. Conversely, it is quite rare in Scandinavian countries and in Asia. It is also important to note that the overall prevalence and severity of Paget's disease have been observed to decline over recent decades, a trend that may be related to changes in nutrition, lifestyle, or environmental exposures.
Proposed Environmental Triggers
In addition to the genetic and geographic factors, researchers have long speculated about potential environmental triggers. Some theories include certain viral infections that may lay dormant for years before triggering the disease in genetically predisposed individuals later in life. However, these environmental links are not yet fully understood and remain an area of ongoing research.
Understanding the Classic vs. Early-Onset Forms
For most people, Paget's disease is a late-onset condition, but it's important to distinguish this from the much rarer juvenile or early-onset forms. The table below compares the key characteristics of these two variants.
| Feature | Classic (Late-Onset) Paget's Disease | Early-Onset Paget's Disease |
|---|---|---|
| Typical Onset Age | Middle age and later (typically over 50) | Teens or twenties |
| Inheritance Pattern | Can be familial (15-40%) or sporadic | Typically inherited in an autosomal dominant pattern |
| Affected Bones | Most commonly pelvis, spine, skull, and long leg bones | More likely to affect the axial skeleton (skull, spine, ribs) and small bones of the hands |
| Prevalence | Fairly common in older adults in specific regions | Extremely rare; reported in only a few families worldwide |
| Associated Genes | SQSTM1 gene mutations frequently associated | Specifically linked to mutations in the TNFRSF11A gene |
| Early Symptoms | Often asymptomatic, diagnosed incidentally; pain, deformity | Hearing loss can be a prominent symptom early in life |
The Role of Bone Remodeling in Paget's Disease
To grasp why age is a critical factor, it's helpful to understand the basic process of bone remodeling and how Paget's disease disrupts it. The following steps show the normal process compared to the one in Paget's:
- In healthy bone, osteoclasts (cells that resorb or break down old bone) and osteoblasts (cells that form new bone) work in a balanced, coordinated manner.
- In Paget's disease, osteoclasts become abnormally large and overactive, leading to excessive and rapid bone resorption.
- This increased resorption triggers a compensatory increase in osteoblast activity, causing the formation of new bone.
- However, this new bone is created in a disorganized, haphazard manner, forming structurally unsound, brittle, and enlarged bone. This is different from the dense, strong bone seen in osteoporosis. Learn more about bone health from the Mayo Clinic.
- Over time, this rapid and disorganized turnover leads to the bone deformities, pain, and fractures characteristic of the disease. The process accelerates with age, which is why it becomes more prevalent later in life.
Diagnosis and Management at Different Ages
For older adults, Paget's disease is often discovered during routine blood tests (which may show elevated alkaline phosphatase) or incidental x-rays. In contrast, early-onset cases may be more actively investigated due to more severe or symptomatic presentations at a younger age. Treatment, which typically involves bisphosphonates to help normalize bone turnover, is tailored to the individual's specific case regardless of age, though earlier diagnosis can help manage symptoms and prevent complications over a longer period.
Conclusion
While the classic form of Paget's disease is most commonly diagnosed in individuals over 50, the question of what age can you get Paget's disease has a more nuanced answer. The age of onset can vary, with rare cases appearing decades earlier. Age is a primary risk factor, but it's one piece of a larger puzzle that includes genetics, ethnicity, and environmental influences. Early identification, regardless of age, is crucial for effective management and preventing long-term complications.
