Physical Trauma and Family History of Neurodegenerative Diseases in Amyotrophic Lateral Sclerosis: A Population-Based Case-Control Study

Abstract

This population-based case-control study was conducted in three counties in western Washington state (USA) between 1990 and 1994 to assess the association between amyotrophic lateral sclerosis (ALS) and several hypothesized risk factors, including a family history of neurodegenerative diseases, physical trauma (fractures, electrical shocks, and surgeries), rural residence, travel, and medical history. One hundred seventy-four cases with ALS, newly diagnosed by neurologists, were identified through several case-finding methods. Two controls (n = 348), who were matched to each case by gender and age (±5 years), were identified through random digit telephone dialing or Medicare lists. Exposure data were collected through structured in-person interviews. A greater proportion of cases (2.3%) than controls (0.9%) reported a first-degree relative with ALS, resulting in an odds ratio of 3.1 (95% CI, 0.6–15.7). For a positive family history of ALS among second-degree relatives, the odds ratio was 4.0 (95% CI, 1.0–16.6). Overall, reports of first- or second-degree relatives with ALS yielded a significantly elevated odds ratio of 3.3 (95% CI, 1.1–9.9). No association was found with a family history of Alzheimer’s disease or Parkinson’s disease, or with a family history of the neurodegenerative diseases as a group. No significant associations were demonstrated for any of the other factors analyzed, including a history of fractures, electrical shocks, or surgeries, a history of residence in rural areas, a history of travel to areas in the western Pacific where ALS is endemic, and a medical history of polio, polio immunization, or tetanus immunization.

Environmental and Occupational Risk Factors for Amyotrophic Lateral Sclerosis: A Case-Control Study

“…The relationship between exposure to pesticides, agricultural occupations and residing in a rural area and risk of ALS has been inconsistent as only about half of the epidemiologic studies, including two meta-analyses, have found an association [14,20,21,22,23,24,25]. However, this finding has not been replicated by some studies [26,27,28,29]. The association of occupational electromagnetic field exposure with ALS has also been investigated, with most published reports indicating a positive relationship [30].…”

Case Series Investigation of Amyotrophic Lateral Sclerosis (ALS) Among Former Kelly Air Force Base Workers

“…It is generally accepted that between 5-10% of ALS cases are familial (and not sporadic) in origin; 18,21 in line with this, 4.3% of our case series had a blood relative with ALS. Similarly, in Cruz et al, 22 5.2% of patients had a blood relative with ALS; their cases were significantly more likely to have blood relatives with ALS than were controls.…”

“…However, in their study of physical trauma and family history of neurological disease, Cruz et al 22 found that 4.6% and 2.3% of their cases' firstdegree relatives had Alzheimer's and Parkinson's disease, respectively; their cases were no different from controls. The percentages of our cases reporting family members with these neurological diseases were somewhat higher, with 8.6% reporting a first-degree relative with Alzheimer's disease and 4.3% reporting a first-degree relative with Parkinson's disease.…”

“…Savitz et al 51 found increasing ALS risk with increasing duration of employment among electrical utility workers. Cruz et al 22 found that 2.3% of their cases had suffered a shock resulting in unconsciousness, while 7.5% of their cases were burned. Their cases were similar to controls.…”

“…Cruz et al 22 calculated the prevalence of polio in their Washington State series at 3.4%. It is difficult to compare our figure with Cruz et al's, though, as their cases were diagnosed over a four-year period in the early 1990s, while our cases were diagnosed over a 30+-year time frame beginning in the 1960s.…”