Evaluation of cerebral blood flow by single-photon emission computed tomography in young Asian Indians with hypertension

Olmesartan, an angiotensin II receptor blocker, restores cerebral hypoperfusion in elderly patients with hypertension

We evaluated the effects of olmesartan, an angiotensin II receptor blocker (ARB), on cerebral blood flow (CBF) in elderly and hypertensive subjects. Ten subjects with first- or second-degree essential hypertension (mean age, 70.5 years) underwent brain single-photon emission tomography (SPECT) scanning with (99m)Tc-ethyl cysteinate dimer before and after a 24-week course of olmesartan. Mean systolic blood pressure (SBP) was 156.2+/-9.9 mm Hg, and mean diastolic blood pressure (DBP) was 89.1+/-5.5mm Hg. No subject had any abnormalities on neurologic examination or previous history of stroke or cardiovascular disease. Before olmesartan administration, the hypertensive subjects had approximately 15% less whole brain CBF compared with age-matched normotensive controls. Regional CBF was decreased by 11%-20% in the frontal, parietal, temporal, and posterior lobes. Olmesartan treatment significantly decreased SBP to 130.4+/-4.2mm Hg (P < .001) and DBP to 78.2+/-7.0mm Hg (P < .001). After 24 weeks of olmesartan treatment, CBF of whole brain and regional CBF of the frontal, parietal, and temporal lobe were similar to those of control subjects. Our brain SPECT data indicate that olmesartan restores brain hypoperfusion in elderly and hypertensive patients without organic damage. This ARB may have a favorable potential for cerebrovascular circulation, in addition to a blood pressure-lowering effect.

Beyond mild cognitive impairment: vascular cognitive impairment, no dementia (VCIND)

Identifying the causes of dementia is important in the search for effective preventative and treatment strategies. The concept of mild cognitive impairment (MCI), as prodromal dementia, has been useful but remains controversial since in population-based studies it appears to be a limited predictor of progression to dementia. Recognising the relative contribution of neurodegenerative and vascular causes, as well as their interrelationship, may enhance predictive accuracy. The concept of vascular cognitive impairment (VCI) has been introduced to describe the spectrum of cognitive change related to vascular causes from early cognitive decline to dementia. A recent review of this concept highlighted the need for diagnostic criteria that encompass the full range of the VCI construct. However, very little is known regarding the mildest stage of VCI, generally termed 'vascular cognitive impairment, no dementia' (VCIND). Whether mild cognitive change in the context of neurodegenerative pathologies is distinct from that in the context of cerebrovascular diseases is not known. This is key to the definition of VCIND and whether it is possible to identify this state. Distinguishing between vascular (that is, VCIND) and non-vascular (that is, MCI) cognitive disorders and determining how well each might predict dementia may not be possible due to the overlap in pathologies observed in the older population. Here, we review the concept of VCIND in an effort to identify recent developments and areas of controversy in nosology and the application of VCIND for screening individuals at increased risk of dementia secondary to vascular disease and its risk factors.

Vascular health risks and fMRI activation during a memory task in older adults

Vascular problems increase Alzheimer's disease (AD) risk, but the nature of this relationship remains unclear. Older adults having genetic risk for AD show regionally increased functional magnetic resonance imaging (fMRI) activity during memory, possibly representing compensation for a genetically induced neural deficit. We investigated whether vascular health risks, which similarly could lead to neuropsychological deficits, also showed increased fMRI activity during a memory task performed by 30 cognitively intact, primarily normotensive older adults (mean age=61). Vascular risk measures included systolic blood pressure (sBP), body mass index (BMI), and total cholesterol. Higher sBP and BMI (but not total cholesterol) were significantly correlated with increased activation in posterior cingulate cortex and frontal, temporal, and parietal regions. In posterior cingulate and parietal cortices, these relationships were evident even within sBP and BMI ranges considered normal, and were independent of hippocampal volume. Our results are similar to those in prior AD risk research, and suggest that fMRI reveals an abnormal response to cognitive processes in cognitively intact older adults with increased vascular risk.