Functional neuroimaging in neurology and psychiatry

Hypertensive Retinopathy and the Risk of Stroke Among Hypertensive Adults in China

Purpose

This study aimed to investigate the association between hypertensive retinopathy and the risk of first stroke, examine possible effect modifiers in hypertensive patients, and test the appropriateness of the Keith-Wagener-Barker (KWB) classification for predicting stroke risk.

Methods

In total, 9793 hypertensive participants (3727 males and 6066 females) without stroke history from the China Stroke Primary Prevention Trial were included in this study. The primary outcome was first stroke.

Results

Over a median follow-up of 4.4 years, 592 participants experienced their first stroke (509 ischemic, 77 hemorrhagic, and six unclassifiable strokes). In total, 5590 participants were diagnosed with grade 1 retinopathy (57.08%), 1466 with grade 2 retinopathy (14.97%), 231 with grade 3 retinopathy (2.36%), and three with grade 4 retinopathy (0.03%). Grades 1 and 2 were merged and classified as mild retinopathy, and grades 3 and 4 were merged and classified as severe retinopathy. There was a significant positive association between hypertensive retinopathy and the risk of first stroke and first ischemic stroke, and no effect modifiers were found. The hazard ratios (HRs) for first stroke were as follows: mild versus no retinopathy, 1.26 (95% confidence interval [CI], 1.01-1.58, P = 0.040), and severe versus no retinopathy, 2.40 (95% CI, 1.49-3.84, P < 0.001). The HRs for ischemic stroke were as follows: severe versus no retinopathy, 2.35 (95% CI, 1.41-3.90, P = 0.001), and nonsignificantly increased HRs for mild versus no retinopathy, 1.26 (95% CI, 0.99-1.60, P = 0.057).

Conclusions

There was a significant positive association between hypertensive retinopathy and the risk of first stroke in patients with hypertension, indicating that hypertensive retinopathy may be a predictor of the risk of stroke. A simplified two-grade classification system based on the KWB classification is recommended for predicting stroke risk.

Acute and subacute changes in neural activation during the recovery from sport-related concussion

To study the natural recovery from sports concussion, 12 concussed high school football athletes and 12 matched uninjured teammates were evaluated with symptom rating scales, tests of postural balance and cognition, and an event-related fMRI study during performance of a load-dependent working memory task at 13 h and 7 weeks following injury. Injured athletes showed the expected postconcussive symptoms and cognitive decline with decreased reaction time (RT) and increased RT variability on a working memory task during the acute period and an apparent full recovery 7 weeks later. Brain activation patterns showed decreased activation of right hemisphere attentional networks in injured athletes relative to controls during the acute period with a reversed pattern of activation (injured > controls) in the same networks at 7 weeks following injury. These changes coincided with a decrease in self-reported postconcussive symptoms and improved cognitive test performance in the injured athletes. Results from this exploratory study suggest that decreased activation of right hemisphere attentional networks mediate the cognitive changes and postconcussion symptoms observed during the acute period following concussion. Conversely, improvement in cognitive functioning and postconcussive symptoms during the subacute period may be mediated by compensatory increases in activation of this same attentional network.

Retinal vascular image analysis as a potential screening tool for cerebrovascular disease: a rationale based on homology between cerebral and retinal microvasculatures

The retinal and cerebral microvasculatures share many morphological and physiological properties. Assessment of the cerebral microvasculature requires highly specialized and expensive techniques. The potential for using non-invasive clinical assessment of the retinal microvasculature as a marker of the state of the cerebrovasculature offers clear advantages, owing to the ease with which the retinal vasculature can be directly visualized in vivo and photographed due to its essential two-dimensional nature. The use of retinal digital image analysis is becoming increasingly common, and offers new techniques to analyse different aspects of retinal vascular topography, including retinal vascular widths, geometrical attributes at vessel bifurcations and vessel tracking. Being predominantly automated and objective, these techniques offer an exciting opportunity to study the potential to identify retinal microvascular abnormalities as markers of cerebrovascular pathology. In this review, we describe the anatomical and physiological homology between the retinal and cerebral microvasculatures. We review the evidence that retinal microvascular changes occur in cerebrovascular disease and review current retinal image analysis tools that may allow us to use different aspects of the retinal microvasculature as potential markers for the state of the cerebral microvasculature.