Resting-State Networks in Alzheimer's Disease and Parkinson's Disease

Abstract

While there is good evidence for altered resting-state networks, particularly the default mode network (DMN), in both Alzheimer's disease (AD) and amnestic mild cognitive impairment preceding AD, there are rather conflicting data on changes in the DMN in Parkinson's disease (PD) and PD with cognitive impairment. This paper will focus on DMN study results, particularly in PD, as assessed by functional MRI.

Non-invasive brain stimulation of the right inferior frontal gyrus may improve attention in early Alzheimer's disease: A pilot study

“…Moreover, the same area (48,21,3) revealed decreased connectivity with the posterior cingulate/precuneus (i.e. the major node of the default mode network) in patients with PD with dementia as compared with healthy age-matched controls [43,44]. In non-demented PD patients, rTMS of the IFG increased the speed of cognitive processing in both the congruent and incongruent conditions of the Stroop test [46].…”

“…[16,25,27,32]). Based on our previous functional magnetic resonance imaging (fMRI) and rTMS results in patients with degenerative brain diseases, we chose two cortical areas to study: the right inferior frontal gyrus (IFG) in order to modulate attention and cognitive speed [4,43,44,46] and the right superior temporal gyrus (STG) in order to manipulate visual processing, visual memory encoding, and recognition [7,27] in AD population. These brain areas are easily accessible by rTMS when the coil is navigated by a frameless stereotaxy.…”

Applications of Resting State Functional MR Imaging to Neuropsychiatric Diseases

“…Because accessory symptoms, such as cognitive disturbances including dementia or visual hallucinations can occur in some, but not all PD patients it is important to note which studies have carefully classified PD patients by the presence or absence of such symptoms, as their presence may be associated with additional RS abnormalities. Several investigations specifically looked for resting state alterations associated with symptoms such as specific cognitive disturbance 106 , dementia 107 , and visual hallucinations 108,109 . One interesting observation is that FC between the DMN and the central executive network appears to be disrupted in PD 104 , perhaps in association with the above-mentioned cognitive symptoms.…”

Irrelevant stimulus processing in ADHD: catecholamine dynamics and attentional networks

“…There are reports of DMN dysfunction in Alzheimer’s and Parkinson’s diseases, although in the latter there are some conflicting data (Rektorova, 2013). However, Delaveau et al (2010) found that Parkinson’s patients fail to deactivate posterior midline or lateral components of the DMN during a facial emotion recognition task .…”