The neuritic plaque in Alzheimer's disease: perivascular degeneration of neuronal processes.

Cerebrovascular pathology is common in aging and Alzheimer's disease (AD). The microvasculature is particularly vulnerable, with capillary-level microhemorrhages coinciding with amyloid beta deposits in senile plaques. In the current analysis, we assessed the relationship between cerebral microvessels and the neuritic component of the plaque in cortical and hippocampal 50- to 200-µm sections from 11 AD, 3 Down syndrome, and 7 nondemented cases in neuritic disease stages 0-VI. We report that 77%-97% of neuritic plaques are perivascular, independently of disease stage or dementia diagnosis. Within neuritic plaques, dystrophic hyperphosphorylated tau-positive neurites appear as clusters of punctate, bulbous, and thread-like structures focused around capillaries and colocalize with iron deposits characteristic of microhemorrhage. Microvessels within the neuritic plaque are narrowed by 1.0 ± 1.0 µm-4.4 ± 2.0 µm, a difference of 16%-65% compared to blood vessel segments with diameters 7.9 ± 2.0-6.4 ± 0.8 µm (p < 0.01) outside the plaque domain. The reduced capacity of microvessels within plaques, frequently below patency, likely compromises normal microlocal cerebrovascular perfusion. These data link the neuritic and amyloid beta components of the plaque directly to microvascular degeneration. Strategies focused on cerebrovascular antecedents to neuritic dystrophy in AD have immediate potential for prevention, detection, and therapeutic intervention.

PACAP and VIP expression in the periaqueductal grey of the rat following sciatic nerve constriction injury.

Nerve injuries often result in neuropathic pain with co-morbid changes in social behaviours, motivation, sleep-wake cycles and neuroendocrine function. In an animal model of neuropathic injury (CCI) similar co-morbid changes are evoked in a subpopulation (~30%) of injured rats. In addition to anatomical evidence of altered neuronal and glial function, the periaqueductal grey (PAG) of these rats shows evidence of cell death. These changes in the PAG may play a role in the disruption of the normal emotional coping responses triggered by nerve injury. Cell death can occur via a number of mechanisms, including the disruption of neuroprotective mechanisms. Pituitary adenylate cyclase activating polypeptide (PACAP) and vasoactive intestinal peptide (VIP) are two endogenous neuropeptides whose activities are tightly regulated by two receptors subtypes, namely the PAC1 and VPAC receptors. These peptides and their receptors exert robust neuroprotective roles. In these studies, we hypothesized that rats expressing disabilities following CCI showed altered expression of PACAP and VIP in the PAG. Rats were categorized as having either Pain alone, Transient or Persistent disability, based on changes in social behaviours pre- and post-CCI. Social interaction behavioural tested (BT), sham-injured and naïve untested rats were also included. For measurements of mRNA and protein expression we utilised micro-dissected PAGs blocks taken from each group. At the mRNA level, VIP was downregulated and PAC1 was upregulated in BT animals, whilst VPAC1 mRNA was specifically increased in the Pain alone group. Interestingly, protein levels of both PACAP and VIP were remarkably increased in the Persistent Disability group. Taken together, sciatic nerve CCI that triggers neuropathic pain and persistent disability results in abnormally increased VIP and PACAP expression in the PAG. Our data also suggest that these effects are likely to be governed by post-transcriptional mechanisms.

Impact of cognitive function on communication in patients with primary or secondary brain tumours.

Communication support tools (CST) improve patient outcomes in oncology including: knowledge, satisfaction, self-management, and adherence to planned treatment. Little is known about communication support tools use in patients with primary or secondary brain tumours. We aimed to explore cognitive function and communication support tool use in this population. This prospective survey involved patients, caregivers and health professionals. Questionnaires were completed after initial brain radiotherapy consultation and 1-2 weeks later. Patients completed the Montreal Cognitive Assessment (MoCA). Descriptive statistics are reported. Fifty-three patients participated, median age 62 years, ECOG status 0-2 (90 %), with 75 % having secondary brain metastasis. 21/53 (40 %) patients reported needing help reading medical information. Only 28 % patients had normal cognition (MoCA score ≥ 26/30). Initially, 82 % of patients and 87 % of caregivers reported the consultation was 'extremely/quite clear, and 69 % of their health professionals thought consultation 'extremely/quite clear' to patient. At follow-up, fewer patients (75 %) reported health professionals' explanation as 'extremely/quite clear'. Although patients recalled discussed illness and treatment details, 82 % recalled treatment-related side effects and management thereof by 46 %. CST use was reported by 22 % patients, 19 % caregivers, and 27 %health professionals. When used, tools improved understanding according to 92 % patients, 100 % caregivers, and 91 % health professionals. The majority of patients have some level of cognitive impairment. Information discussed appears clear to most patients, but this is not sustained, and recall of treatment toxicity management is poor. Few CSTs are used in consultations, but when used, are reported as helpful by all.