Early infections linked to Parkinson's and Alzheimer's risk

Early and midlife infections treated in outpatient or inpatient hospital settings upped the risk of a subsequent Alzheimer's or Parkinson's disease diagnosis, a case-control study in Sweden showed.

A hospital-treated infection 5 or more years before diagnosis was associated with a 16% higher risk of Alzheimer's (95% CI 1.15-1.18, P<0.001) and a 4% higher risk of Parkinson's (95% CI 1.02-1.06, P<0.001), according to Jiangwei Sun, PhD, of Karolinska Institute in Stockholm, and colleagues.

Multiple hospital-treated infections before age 40 doubled the risk of a subsequent Alzheimer's diagnosis (OR 2.62, 95% CI 2.52-2.72, P<0.001) and raised the risk of a Parkinson's diagnosis by about 40% (OR 1.41, 95% CI 1.29-1.53, P<0.001), the researchers reported in .

The associations were due primarily to Alzheimer's and Parkinson's diagnosed before age 60 (OR 1.93, 95% CI 1.89-1.98 for Alzheimer's, P<0.001; OR 1.29, 95% CI 1.22-1.36 for Parkinson's, P<0.001). No associations emerged for people diagnosed at age 60 or older.

Similar risks were seen for bacterial, viral, and other infections and for different sites of infection, including gastrointestinal and genitourinary infections.