**5. Neuroimaging of mild cognitive impairment**

Early radiological studies in MCI were focused on the assessment of the entorhinal cortex (ERC) and hippocampus. Volume of the ERC and the hippocampus in MCI patients tends to be smaller and is either intermediate between normal controls and patients with AD, or similar to AD. Some studies demonstrated higher sensitivity of the entorhinal cortex compared with hippocampal volume. The annualized rate of the hippocampal and entorhinal cortex atrophy has been shown to be more prominent in the MCI patients relative to normal controls [5, 34].

Apart from medial temporal lobe atrophy, decrease in gray matter volume was reported in the lateral temporal, parietal, and frontal lobes, amygdala, fusiform gyrus, cingulate, parietal and occipital lobes and insula. Several studies have documented that the whole brain volume loss rate is associated with objective cognitive decline over time.

Apostolova et al. followed a cohort of MCI subjects clinically and neuropsychologically for 3 years. They found that smaller hippocampal volumes predict conversion of MCI to AD and patients with MCI who convert to AD have greater atrophy in the CA1 and subiculum regions of the hippocampus [35].

Several studies reported significant alterations on diffusion weighted MR imaging (DWI) measures in the hippocampus, thalamus, posterior cingulum (PC) and several regions in posterior white matter in MCI patients. Kantarci et al. found that on the follow up, elevated hippocampal diffusivity predicts MCI progression to AD better than hippocampal volumetry [5, 36].

Study by Delano-Wood et al. showed that diminished white matter integrity of PC was strongly predictive of MCI status. Additionally, patients with amnestic MCI demonstrated lower PC white matter integrity relative to those with non-amnestic MCI [5, 34].

Compared with conventional medicine alone, Ginkgo biloba in combination with conventional medicine was superior in improving Mini-Mental State Examination (MMSE) scores for patients with Alzheimer's disease and mild cognitive impairment. When compared with placebo or conventional medicine in individual trials, Ginkgo biloba demonstrated similar

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http://dx.doi.org/10.5772/intechopen.75509

The Ginkgo Evaluation of Memory (GEM Study) study was a randomized, double-blind placebo-controlled multicenter trial, which was held in 2000–2008 years in the United States. Out of 3069 participants of the clinical trial, most of them (n=2587) didn't have cognitive dysfunction, and 15.7% (n=482) were diagnosed with mild cognitive impairment on the basis of Peterson's criteria. After completion of the 6 -year observation period no significant effect of

There is an evidence, that inflammation plays an important role in the pathophysiology of Alzheimer's disease. Several epidemiological studies showed negative association between usage of anti-inflammatory nonsteroidal medications and development of Alzheimer's disease. For example, the Canadian Study of Health and Aging involving 5276 cognitively normal subjects demonstrated that there is an association between NSAID use and a lower

One large multicenter study on the efficacy of the COX-II inhibitor in preventing dementia has been conducted. In the trial participated 1457 subjects with mild cognitive impairment, half of them were taking Rofecoxib, approximately for 4 years. Trial revealed significantly

A randomized, double-blind, placebo-controlled trial of Triflusal in patients with amnestic mild cognitive impairment reported no significant effect of Triflusal treatment on cognition,

Centrally acting angiotensin-converting enzyme inhibitors (CACE-Is) have demonstrated positive effect on cognitive function in a study including 361 patients with AD, vascular dementia, or mixed dementias, regardless of blood pressure levels at the time of their hypertension diagnosis. Piridebil is an antagonist of dopamine receptors. Based on experimental trials it increases acetylcholine release in hippocampus and frontal cortex. Piribedil improved cognition over 3 months

The role of B vitamins was studied in few clinical trials. However, the data does not yet provide adequate evidence of an effect of vitamins B on general cognitive function, executive function and attention in people with MCI. Similarly, B vitamins are unable to stabilize or

Twelve-week treatment with dietary supplementation containing an oily emulsion of docosahexaenoic acid (DHA)-phospholipids demonstrated considerable improvement in cognitive function in 25 elderly patients with MCI in a randomized controlled study. Studies support the effectiveness of omega 3 fatty acids such as docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) on cognitive function, depressive symptoms and general functioning in

Ginkgo biloba on the incidence of dementia could be demonstrated [40].

incidence of AD and cognitive impairment no dementia (CIND) [38].

high frequency of Alzheimer's disease in the group that used Rofecoxib [38].

although it was associated with a reduced risk of conversion to AD [38].

in individuals with MMSE of 21–25, in one small placebo controlled study.

persons with MCI [41].

slow decline in cognition, function, behavior, and global change of AD patients.

but inconsistent findings. Adverse events were mild.

FDG-PET ([18F]-2-fluoro-2-deoxy-D-glucose-positron emission tomography) studies have found substantial reduction in brain activity in some cortical regions (HC limbic system, medial thalamus, and posterior cingulate). These findings are consistent with structural MRI findings [5, 37].

SPECT studies have reported reduced cerebral blood flow (CBF) in the parietal cortex, posterior cingulated cortex and precuneus in persons with MCI. Longitudinal SPECT studies showed that the presence of AD-like hypoperfusion in the posterior posterior cingulate cortex of patients in MCI was predictive of conversion to AD [37].

Accumulation of amyloid-β (Aβ) fibrils in the form of amyloid plaques is a neuropathological hallmark of dementia caused by AD. Amyloid deposition appears an early event in AD, possibly occurring up to 20 years before clinical symptoms. Amyloid imaging has become one of the central biomarkers of AD and predictor of cognitive decline. There is evidence that a positive amyloid PET scan result in patients with MCI will help in predicting conversion to AD. Amyloid-PET may help to differentiate between different etiologies of cognitive dysfunction and in the future it may help to appropriately select patients for anti-amyloid therapy [5].
