One-year Follow-up of Neuropsychology, MRI, rCBF and Glucose Metabolism (rMRGlu) in Cerebral Microangiopathy

Neuroimaging in Vascular Cognitive Impairment and Dementia: A Systematic Review

Cerebrovascular diseases are well established causes of cognitive impairment. Different etiologic entities, such as vascular dementia (VaD), vascular cognitive impairment, subcortical (ischemic) VaD, and vascular cognitive disorder, are included in the umbrella definition of vascular cognitive impairment and dementia (VCID). Because of the variability of VCID clinical presentation, there is no agreement on criteria defining the neuropathological threshold of this disorder. In fact, VCID is characterized by cerebral hemodynamic alteration which ranges from decreased cerebral blood flow to small vessels disease and involves a multifactorial process that leads to demyelination and gliosis, including blood-brain barrier disruption, hypoxia, and hypoperfusion, oxidative stress, neuroinflammation and alteration on neurovascular unit coupling, cerebral microbleeds, or superficial siderosis. Numerous criteria for the definition of VaD have been described: the National Institute of Neurological Disorders and Stroke Association Internationale pour Recherche'-et-l'Enseignement en Neurosciences criteria, the State of California Alzheimer's Disease Diagnostic and Treatment Centers criteria, DSM-V criteria, the Diagnostic Criteria for Vascular Cognitive Disorders (a VASCOG Statement), and Vascular Impairment of Cognition Classification Consensus Study. Neuroimaging is fundamental for definition and diagnosis of VCID and should be used to assess the extent, location, and type of vascular lesions. MRI is the most sensible technique, especially if used according to standardized protocols, even if CT plays an important role in several conditions. Functional neuroimaging, in particular functional MRI and PET, may facilitate differential diagnosis among different forms of dementia. This systematic review aims to explore the state of the art and future perspective of non-invasive diagnostics of VCID.

Cerebral small vessel disease: how does it progress?

Small vessel disease (SVD), or microangiopathy, of the cerebral white and central grey matter is an important subtype of vascular dementia (VD). SVD-dementia is characterised by a "dysexecutive" type of cognitive impairment, neurological deficits including imbalance and voiding dysfunction, and emotional disturbances. SVD is also frequent among clinically healthy subjects and patients with mild cognitive impairment. It is easily visualised by imaging techniques, but difficult to distinguish from mixed SVD/Alzheimer Disease. SVD has an inherent tendency to progress, but data on its natural course are sparse, and there are almost no drug trials dedicated to it. This article reviews the evidence on the speed and predictors of progression of SVD in regard to cognitive deficits, functional decline and white matter lesions, as derived from epidemiological, clinical and imaging studies and the placebo branches of VD drug trials. Based on the available data, we make suggestions for future research and outcome measures.

Cognitive impairment is related to cerebral lactate in patients with carotid artery occlusion and ipsilateral transient ischemic attacks

BACKGROUND AND PURPOSE

Patients with carotid artery occlusion (CAO) and ipsilateral transient ischemic attack (TIA) can have lasting cognitive impairment, despite the recovery of focal neurological deficits. We sought to assess whether cognitive impairment in these patients is associated with hemodynamic compromise and/or impaired cerebral metabolism.

METHODS

In 39 consecutive patients with a TIA associated with an angiographically proven occlusion of the carotid artery, we examined (1) cognitive functioning, (2) cerebrovascular reserve capacity of the middle cerebral artery ipsilateral to the CAO as measured by transcranial Doppler ultrasound, and (3) metabolic ratios as measured by 1H-MR spectroscopy in the centrum semiovale ipsilateral to the symptomatic CAO. Findings were compared with those in healthy control subjects.

RESULTS

As a group, patients were cognitively impaired. Mean CO2 reactivity and the mean ratio of N-acetyl aspartate to creatine were decreased. In approximately one third of patients, lactate was present in noninfarcted regions. The presence of lactate proved to be a stronger correlate of cognitive impairment than MRI-detected lesions (beta=0.41 versus beta=0.15). Cognitive impairment did not correlate with CO2 reactivity or the ratio of N-acetyl aspartate to creatine.

CONCLUSIONS

This exploratory study in patients with CAO and ipsilateral TIA showed that 1H-MR spectroscopy-detected lactate in noninfarcted regions is a better indicator of cognitive impairment than MRI-detected lesions. Cognitive impairment did not correlate with CO2 reactivity.