Cerebrovascular reactivity in depressed patients without vascular risk factors

Background: Cerebrovascular reactivity (CVR) seems to be gaining importance as a prognostic factor for stroke risk. CVR reflects the compensatory dilatory capacity of cerebral arterioles to a dilatory stimulus; this mechanism plays an important role in maintaining a constant cerebral blood flow. Evaluating factors that influence CVR will help prevention or early detection of cerebrovascular disease (CVD). Objectives: To measure the CVR in vascular-risk free depressed individuals so as to evaluate the effect depression has on CVR and hence its role as a stroke risk factor. Methods: Using acetazolamid (ACZ) stimulation, CVR was assessed with a transcranial Doppler ultrasound in 25 non-smoking depressed patients (mean age: 48.48±14.40) and in 25 healthy non-smoking controls (mean age: 46.76±13.69) by calculating the difference between the maximal mean blood flow velocity at baseline and the maximal mean blood flow velocity after ACZ stimulation. Results: Basal cerebral blood flow in patients was 50.6cm/s (SD: 11.6) versus controls 52.80cm/s (SD: 12.70), whereas after stimulation maximal blood flow velocity was 72.64cm/s (SD: 15.75) in patients versus 80.20cm/s (SD: 18.43) in controls. In an analysis of covariance we found that cerebrovascular reactivity was significantly reduced in the vascular-risk free depressed sample. Age had a significant influence whereas gender did not. Conclusions: Major Depression appears to decrease cerebrovascular reactivity, supporting the idea that depressed patients have an increased risk of suffering from stroke. The mechanisms leading to this phenomenon and its subtle subgroup differences should be further investigated.