Cerebral vasomotor reactivity and dementia after ischemic stroke

Dementia Risk Following Ischemic Stroke: A Systematic Review and Meta-Analysis of Factors Collected at Time of Stroke Diagnosis

BACKGROUND

The majority of stroke cases are ischemic in origin and ischemic stroke survivors represent a high-risk population for progression to dementia.

OBJECTIVE

To determine incidence rates and predictors of dementia after ischemic stroke.

METHODS

A systematic review and meta-analysis compliant with Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA).

RESULTS

5,843 studies were screened for title and abstract. 292 eligible studies were screened for full text. A total of 22 studies met the inclusion criteria and were included, representing 55,929 ischemic stroke survivors. Cumulative incidence of dementia after stroke was 20% at 5 years, 30% at 15 years, and 48% at 25 years of follow-up. Dementia incidence rates were 1.5 times higher among patients with recurrent ischemic stroke compared to patients with first-time stroke. Predictors of dementia after ischemic stroke included female gender (OR 1.2, 95% CI (1.1, 1.4)), hypertension (1.4, (1.1, 2.0)), diabetes mellitus (1.6, (1.3, 2.1)), atrial fibrillation (1.9, (1.2, 3.0)), previous stroke (2.0, (1.6, 2.6)), presence of stroke lesion in dominant hemisphere (2.4, (1.3, 4.5)), brain stem or cerebellum (OR 0.5, (0.3, 0.9)) or frontal lobe (3.7, (1.2, 12.0)), presence of aphasia (OR 7.9, (2.4, 26.0)), dysphasia (5.8, (3.0, 11.3)), gait impairment (1.7, (1.1, 2.7)), presence of white matter hyperintensities (3.2, (2.0, 5.3)), and medial temporal lobe atrophy (3.9, (1.9, 8.3)).

CONCLUSION

Factors routinely collected for stroke patients are a useful resource for monitoring dementia progression in this population. In the present meta-analysis, cardiovascular factors, stroke location, stroke-related disability and chronic brain changes were predictors of dementia after ischemic stroke.

Cerebral Autoregulation in Ischemic Stroke: From Pathophysiology to Clinical Concepts

Ischemic stroke (IS) is one of the most impacting diseases in the world. In the last decades, new therapies have been introduced to improve outcomes after IS, most of them aiming for recanalization of the occluded vessel. However, despite this advance, there are still a large number of patients that remain disabled. One interesting possible therapeutic approach would be interventions guided by cerebral hemodynamic parameters such as dynamic cerebral autoregulation (dCA). Supportive hemodynamic therapies aiming to optimize perfusion in the ischemic area could protect the brain and may even extend the therapeutic window for reperfusion therapies. However, the knowledge of how to implement these therapies in the complex pathophysiology of brain ischemia is challenging and still not fully understood. This comprehensive review will focus on the state of the art in this promising area with emphasis on the following aspects: (1) pathophysiology of CA in the ischemic process; (2) methodology used to evaluate CA in IS; (3) CA studies in IS patients; (4) potential non-reperfusion therapies for IS patients based on the CA concept; and (5) the impact of common IS-associated comorbidities and phenotype on CA status. The review also points to the gaps existing in the current research to be further explored in future trials.

Ultrasound and dynamic functional imaging in vascular cognitive impairment and Alzheimer's disease

BACKGROUND

The vascular contributions to neurodegeneration and neuroinflammation may be assessed by magnetic resonance imaging (MRI) and ultrasonography (US). This review summarises the methodology for these widely available, safe and relatively low cost tools and analyses recent work highlighting their potential utility as biomarkers for differentiating subtypes of cognitive impairment and dementia, tracking disease progression and evaluating response to treatment in various neurocognitive disorders.

METHODS

At the 9th International Congress on Vascular Dementia (Ljubljana, Slovenia, October 2015) a writing group of experts was formed to review the evidence on the utility of US and arterial spin labelling (ASL) as neurophysiological markers of normal ageing, vascular cognitive impairment (VCI) and Alzheimer's disease (AD). Original articles, systematic literature reviews, guidelines and expert opinions published until September 2016 were critically analysed to summarise existing evidence, indicate gaps in current knowledge and, when appropriate, suggest standards of use for the most widely used US and ASL applications.

RESULTS

Cerebral hypoperfusion has been linked to cognitive decline either as a risk or an aggravating factor. Hypoperfusion as a consequence of microangiopathy, macroangiopathy or cardiac dysfunction can promote or accelerate neurodegeneration, blood-brain barrier disruption and neuroinflammation. US can evaluate the cerebrovascular tree for pathological structure and functional changes contributing to cerebral hypoperfusion. Microvascular pathology and hypoperfusion at the level of capillaries and small arterioles can also be assessed by ASL, an MRI signal. Despite increasing evidence supporting the utility of these methods in detection of microvascular pathology, cerebral hypoperfusion, neurovascular unit dysfunction and, most importantly, disease progression, incomplete standardisation and missing validated cut-off values limit their use in daily routine.

CONCLUSIONS

US and ASL are promising tools with excellent temporal resolution, which will have a significant impact on our understanding of the vascular contributions to VCI and AD and may also be relevant for assessing future prevention and therapeutic strategies for these conditions. Our work provides recommendations regarding the use of non-invasive imaging techniques to investigate the functional consequences of vascular burden in dementia.

Neuroregeneration and dementia: new treatment options

In the last years, physiological aging became a general concept that includes all the changes that occur in organism with old age. It is obvious now, that in developing and developed countries, new health problems concerning older population appear. One of these major concerns is probably dementia. Sooner or later, all forms of dementia lead to learning deficit, memory loss, low attention span, impairment of speech and poor problem solving skills. Normal ageing is a physiological process that also involves a lot of neurological disorders with the same type of symptoms and effects that many researchers are trying to minimize in demented patients. In this review we try to highlight some of the newest aspects of therapeutic strategies that can improve natural neuroregeneration.

Cerebrovascular function in aging and dementia: a systematic review of transcranial Doppler studies

Background/Aim

The contribution of cerebrovascular dysfunction to the manifestation of dementia and cognitive decline in late life is gaining increased attention. We aimed to systematically review evidence for associations between dementia or aging and cerebrovascular function as measured using transcranial Doppler (TCD) examination.

Methods

A total of 1,172 articles were retrieved from PsychInfo and PubMed searches, and 34 relevant articles were identified using a variety of TCD methods.

Results

The pulsatility index (vessel resistance), spontaneous emboli and cerebrovascular reactivity to hyper-/hypocapnia appeared good discriminators of dementia. Aging was associated with a slowing in blood flow velocity.

Conclusion

TCD ultrasonography is inexpensive, portable and well tolerated by aged and demented subjects. The technique stands to make a valuable contribution to the knowledge regarding the underlying functional biology of age-related cognitive change and dementia.