Vascular factors in suspected normal pressure hydrocephalus

We examined clinical and imaging findings of suspected idiopathic normal pressure hydrocephalus (iNPH) in relation to vascular risk factors and white matter lesions (WMLs), using a nested case-control design in a representative, population-based sample.From a population-based sample, 1,235 persons aged 70 years or older were examined with CT of the brain between 1986 and 2000. We identified 55 persons with hydrocephalic ventricular enlargement, i.e., radiologic findings consistent with iNPH. Among these, 26 had clinical signs that fulfilled international guideline criteria for probable iNPH. These cases were labeled suspected iNPH. Each case was matched to 5 controls from the same sample, based on age, sex, and study cohort. Data on risk factors were obtained from clinical examinations and the Swedish Hospital Discharge Register. History of hypertension, diabetes mellitus (DM), smoking, overweight, history of coronary artery disease, stroke/TIA, and WMLs on CT were examined. Risk factors associated with iNPH with a p value <0.1 in χ2 tests were included in conditional logistic regression models.In the regression analyses, suspected iNPH was related to moderate to severe WMLs (odds ratio [OR] 5.2; 95% confidence interval [CI]: 1.5-17.6), while hydrocephalic ventricular enlargement was related to hypertension (OR 2.7; 95% CI: 1.1-6.8), moderate to severe WMLs (OR 6.5; 95% CI: 2.1-20.3), and DM (OR 4.3; 95% CI: 1.1-16.3).Hypertension, WMLs, and DM were related to clinical and imaging features of iNPH, suggesting that vascular mechanisms are involved in the pathophysiology. These findings might have implications for understanding disease mechanisms in iNPH and possibly prevention.