Neuron loss in key cholinergic and aminergic nuclei in Alzheimer disease: a meta-analysis.
ABSTRACT Cell counts in the cholinergic nucleus basalis (NB), noradrenergic locus coeruleus (LC), dopaminergic substantia nigra (SN), and the serotonergic dorsal raphe nucleus (DRN) were assessed from primary-level reports in patients with Alzheimer disease (AD) and in controls. Sixty-seven studies that covered about 20 years were included in the meta-analysis. Effect sizes were computed as a standardized mean difference (d) in cell counts between AD and controls. Effect sizes were largest in magnitude for the NB (mean d=2.48, 33 studies, N=585), and the LC (d=2.28, 24 studies, N=545), then the DRN (d=1.79, 11 studies, N=234), and were smallest for the SN (d=0.61, 14 studies, N=440). In general, the overall effect size estimates for the four cell areas were reliable. Using effect size magnitude in the SN as a referent, cell loss was about three times greater in the DRN and four times greater in the NB and LC. Symptomatic drug treatment for AD might be beneficially directed toward ameliorating multiple neurotransmitter deficiencies, particularly cholinergic and noradrenergic.
Article: β-Adrenergic Receptors and G Protein-Coupled Receptor Kinase-2 in Alzheimer's Disease: A New Paradigm for Prognosis and Therapy?[show abstract] [hide abstract]
ABSTRACT: Alzheimer's disease (AD) is a devastating form of dementia that imposes a severe burden on health systems and society. Although several aspects of AD pathogenesis have been elucidated over the last few decades, many questions still need to be addressed. In fact, currently available medications only provide symptomatic improvement in patients with AD without affecting disease progression. The β-adrenergic receptor (β-AR) system can be considered a possible target that deserves further exploration in AD. The central noradrenergic system undergoes substantial changes in the course of AD and β-ARs have been implicated not only in amyloid formation in AD brain but also in amyloid-induced neurotoxicity. Moreover, clinical evidence suggests a protective role of β-AR blockers on AD onset. In addition to that, post-receptor components of β-AR signaling seem to have a role in AD pathogenesis. In particular, the G protein coupled receptor kinase 2, responsible for β-AR desensitization and downregulation, mediates amyloid-induced β-AR dysfunction in neurons, and its levels in circulating lymphocytes of AD patients are increased and inversely correlated with patient's cognitive status. Therefore, there is an urgent need to gain further insight on the role of the adrenergic system components in AD pathogenesis in order to translate preclinical and clinical knowledge to more efficacious prognostic and therapeutic strategies.Journal of Alzheimer's disease: JAD 12/2012; · 3.74 Impact Factor
Article: The Association of Neuropsychiatric Symptoms in MCI With Incident Dementia and Alzheimer Disease.[show abstract] [hide abstract]
ABSTRACT: OBJECTIVES:: Individuals with mild cognitive impairment (MCI) are at high risk of developing dementia and/or Alzheimer disease (AD). Among persons with MCI, depression and anxiety have been associated with an increased risk of incident dementia. We examined whether neuropsychiatric symptoms in MCI increased the risk of incident dementia (all-cause) and incident AD. DESIGN:: Longitudinal cohort study followed annually (median: 1.58 years). SETTING:: National Alzheimer's Coordinating Center database combining clinical data from 29 Alzheimer's Disease Centers. PARTICIPANTS:: A total of 1,821 participants with MCI. MEASUREMENTS:: 1) Progression to dementia (all-cause) or AD, 2) Neuropsychiatric Inventory Questionnaire (NPI-Q), 3) Geriatric Depression Scale (GDS), 4) Clinical Dementia Rating Global Score and Sum of Boxes, and 5) Mini-Mental State Examination(MMSE). The association of covariates with risk of incident dementia or AD was evaluated with hazard ratios (HR) determined by Cox proportional-hazards models adjusted for age, ethnicity, Clinical Dementia Rating Global Score and Sum of Boxes, and MMSE. RESULTS:: A total of 527 participants (28.9%) progressed to dementia and 454 (24.9%) to AD. Baseline GDS > 0 was associated with an increased risk of incident dementia (HR: 1.47, 95% CI: 1.17-1.84) and AD (HR: 1.45, 95% CI: 1.14-1.83). Baseline NPI > 0 was associated with an increased risk of incident dementia (HR: 1.37, 95% CI: 1.12-1.66) and AD (HR: 1.35, 95% CI: 1.09-1.66). CONCLUSIONS:: Neuropsychiatric symptoms in MCI are associated with significantly an increased risk of incident dementia and AD. Neuropsychiatric symptoms may be among the earliest symptoms of preclinical stages of AD and targeting them therapeutically might delay transition to dementia.The American journal of geriatric psychiatry: official journal of the American Association for Geriatric Psychiatry 04/2012; · 3.35 Impact Factor
Article: Locus coeruleus damage and noradrenaline reductions in multiple sclerosis and experimental autoimmune encephalomyelitis.[show abstract] [hide abstract]
ABSTRACT: The endogenous neurotransmitter noradrenaline exerts anti-inflammatory and neuroprotective effects in vitro and in vivo. Several studies report that noradrenaline levels are altered in the central nervous system of patients with multiple sclerosis and rodents with experimental autoimmune encephalomyelitis, which could contribute to pathology. Since the major source of noradrenaline are neurons in the locus coeruleus, we hypothesized that alterations in noradrenaline levels are a consequence of stress or damage to locus coeruleus neurons. In C57BL/6 mice immunized with myelin oligodendrocyte glycoprotein peptide 35-55 to develop chronic disease, cortical and spinal cord levels of noradrenaline were significantly reduced versus control mice. Immunohistochemical staining revealed increased astrocyte activation in the ventral portion of the locus coeruleus in immunized mice. The immunized mice showed neuronal damage in the locus coeruleus detected by a reduction of average cell size of tyrosine hydroxylase stained neurons. Analysis of the locus coeruleus of multiple sclerosis and control brains showed a significant increase in astrocyte activation, a reduction in noradrenaline levels, and neuronal stress indicated by hypertrophy of tyrosine hydroxylase stained cell bodies. However, the magnitude of these changes was not correlated with extent of demyelination or of cellular infiltrates. Together these findings demonstrate the presence of inflammation and neuronal stress in multiple sclerosis as well as in experimental autoimmune encephalomyelitis. Since reduced noradrenaline levels could be permissive for increased inflammation and neuronal damage, these results suggest that methods to raise noradrenaline levels or increase locus coeruleus function may be of benefit in treating multiple sclerosis.Brain 02/2011; 134(Pt 3):665-77. · 9.46 Impact Factor