Experimental laboratory models as tools for understanding modifiable dementia risk.

Experimental laboratory research has an important role to play in dementia prevention. Mechanisms underlying modifiable risk factors for dementia are promising targets for dementia prevention but are difficult to investigate in human populations due to technological constraints and confounds. Therefore, controlled laboratory experiments in models such as transgenic rodents, invertebrates and in vitro cultured cells are increasingly used to investigate dementia risk factors and test strategies which target them to prevent dementia. This review provides an overview of experimental research into 15 established and putative modifiable dementia risk factors: less early-life education, hearing loss, depression, social isolation, life stress, hypertension, obesity, diabetes, physical inactivity, heavy alcohol use, smoking, air pollution, anesthetic exposure, traumatic brain injury, and disordered sleep. It explores how experimental models have been, and can be, used to address questions about modifiable dementia risk and prevention that cannot readily be addressed in human studies. HIGHLIGHTS: Modifiable dementia risk factors are promising targets for dementia prevention. Interrogation of mechanisms underlying dementia risk is difficult in human populations. Studies using diverse experimental models are revealing modifiable dementia risk mechanisms. We review experimental research into 15 modifiable dementia risk factors. Laboratory science can contribute uniquely to dementia prevention.

Early Life Stress Alters Expression of Glucocorticoid Stress Response Genes and Trophic Factor Transcripts in the Rodent Basal Ganglia.

Early life stress shapes the developing brain and increases risk for psychotic disorders. Yet, it is not fully understood how early life stress impacts brain regions in dopaminergic pathways whose dysfunction can contribute to psychosis. Therefore, we investigated gene expression following early life stress in adult brain regions containing dopamine neuron cell bodies (substantia nigra, ventral tegmental area (VTA)) and terminals (dorsal/ventral striatum). Sprague-Dawley rats (14F, 10M) were separated from their mothers from postnatal days (PND) 2-14 for 3 h/day to induce stress, while control rats (12F, 10M) were separated for 15 min/day over the same period. In adulthood (PND98), brain regions were dissected, RNA was isolated and five glucocorticoid signalling-related and six brain-derived neurotrophic factor (Bdnf) mRNAs were assayed by qPCR in four brain regions. In the VTA, levels of glucocorticoid signalling-related transcripts differed in maternally separated rodents compared to controls, with the Fkbp5 transcript significantly lower and Ptges3 transcript significantly higher in stressed offspring. In the VTA and substantia nigra, maternally separated rodents had significantly higher Bdnf IIA and III mRNA levels than controls. By contrast, in the ventral striatum, maternally separated rodents had significantly lower expression of Bdnf I, IIA, IIC, IV and VI transcripts. Sex differences in Nr3c1, Bag1 and Fkbp5 expression in the VTA and substantia nigra were also detected. Our results suggest that early life stress has long-lasting impacts on brain regions involved in dopamine neurotransmission, changing the trophic environment and potentially altering responsiveness to subsequent stressful events in a sex-specific pattern.

Dysregulations of Synaptic Vesicle Trafficking in Schizophrenia.

Schizophrenia is a serious psychiatric illness which is experienced by about 1 % of individuals worldwide and has a debilitating impact on perception, cognition, and social function. Over the years, several models/hypotheses have been developed which link schizophrenia to dysregulations of the dopamine, glutamate, and serotonin receptor pathways. An important segment of these pathways that have been extensively studied for the pathophysiology of schizophrenia is the presynaptic neurotransmitter release mechanism. This set of molecular events is an evolutionarily well-conserved process that involves vesicle recruitment, docking, membrane fusion, and recycling, leading to efficient neurotransmitter delivery at the synapse. Accumulated evidence indicate dysregulation of this mechanism impacting postsynaptic signal transduction via different neurotransmitters in key brain regions implicated in schizophrenia. In recent years, after ground-breaking work that elucidated the operations of this mechanism, research efforts have focused on the alterations in the messenger RNA (mRNA) and protein expression of presynaptic neurotransmitter release molecules in schizophrenia and other neuropsychiatric conditions. In this review article, we present recent evidence from schizophrenia human postmortem studies that key proteins involved in the presynaptic release mechanism are dysregulated in the disorder. We also discuss the potential impact of dysfunctional presynaptic neurotransmitter release on the various neurotransmitter systems implicated in schizophrenia.

Glucocorticoid receptor mRNA and protein isoform alterations in the orbitofrontal cortex in schizophrenia and bipolar disorder.

BACKGROUND: The orbitofrontal cortex (OFC) may play a role in the pathogenesis of psychiatric illnesses such as bipolar disorder and schizophrenia, in which hypothalamic-pituitary-adrenal (HPA) axis abnormalities are observed and stress has been implicated. A critical component of the HPA axis which mediates cellular stress responses in the OFC, and has been implicated in psychiatric illness, is the glucocorticoid receptor (GR). METHODS: In the lateral OFC, we employed quantitative real-time PCR and western blotting to investigate GR mRNA and protein expression in 34 bipolar disorder cases, 35 schizophrenia cases and 35 controls. Genotype data for eleven GR gene (NR3C1) polymorphisms was also used to explore possible effects of NR3C1 sequence variation on GR mRNA and protein expression in the lateral OFC. RESULTS: We found no diagnostic differences in pan GR, GR-1C or GR-1F mRNA expression. However, the GR-1B mRNA transcript variant was decreased (14.3%) in bipolar disorder cases relative to controls (p < 0.05), while GR-1H mRNA was decreased (22.0%) in schizophrenia cases relative to controls (p < 0.005). By western blotting, there were significant increases in abundance of a truncated GRα isoform, putative GRα-D1, in bipolar disorder (56.1%, p < 0.005) and schizophrenia (31.5% p < 0.05). Using genotype data for eleven NR3C1 polymorphisms, we found no evidence of effects of NR3C1 genotype on GR mRNA or GRα protein expression in the OFC. CONCLUSIONS: These findings reveal selective abnormalities of GR mRNA expression in the lateral OFC in psychiatric illness, which are more specific and may be less influenced by NR3C1 genotype than those of the dorsolateral prefrontal cortex reported previously. Our results suggest that the GRα-D1 protein isoform may be up-regulated widely across the frontal cortex in psychiatric illness.

Evidence over barriers: important but not enough.

Overcoming the boundary conditions that impede the flow of evidence derived from research from academia to healthcare decision-makers in government and their agencies continues to be a challenge. But even the reduction/elimination of all such barriers and perfect collaboration are unlikely to yield what those of us in the "real world" yearn for, doing the right things right - policy and other decisions perfectly informed by evidence of what works and what doesn't to achieve a defined outcome. For that to happen, the calculus of decision-makers would have to exclude or evidence would have to trump political considerations, both large P and small p, an unlikely accomplishment in British Columbia or anywhere in our so-called healthcare system. That's reality!

Healthcare and physician leadership.

At a recent social policy conference - Recovering Together? Fiscal Pressures, Federalism and Social Policy, hosted by Queen's International Institute on Social Policy - there was much discussion of "healthcare's crowding out" of others of the determinants of health, education and income security being the predominant examples. I was struck by the loose language, four words/phrases in particular, used to describe reality - healthcare, system, single-payer and publicly funded. Physicians are increasingly moving beyond their already-demanding clinical roles to become chief executive officers (CEOs), chiefs of staff, clinical leaders, board members, deans and directors. Is this a good thing, and should physician leadership be encouraged? Or as Ron Liepert (2009, August), minister of Alberta Health and Wellness, asserts, are physicians better at diagnosing and treating people than running $8 billion organizations?

Long-Term Care's Financial Sustainability.

A system of facilities and services to support and care for Canada's elderly people is essential and must be sustained, but long-term care (LTC), as we now know it, is not it. It is not sustainable financially either by our governments or its current and future recipients. On the upside, the policy direction should easily be changed given that those recipients' strong preference is to age in place in their own homes and communities, not in institutional care homes.

Change in modifiable dementia risk factors during COVID-19 lockdown: The experience of over 50s in Tasmania, Australia.

INTRODUCTION: Containment measures implemented to minimize the spread of coronavirus disease 2019 (COVID-19) are reported to be negatively affecting mental health, diet, and alcohol consumption. These factors, as well as poor cardiometabolic health and insufficient physical and cognitive activity, are known to increase the risk of developing dementia. COVID-19 "lockdown" measures may have exacerbated these dementia risk factors among people in mid-to-later life. METHODS: We compared longitudinal data from before (October 2019) and during (April-June 2020) the first COVID-19 lockdown period in Tasmania, Australia. Participants (n = 1671) were 50+ years of age and engaged in a public health program targeting dementia risk reduction, with one-third participating in the Preventing Dementia Massive Open Online Course (PD-MOOC). Regression models were used to assess changes in smoking, alcohol use, body mass index (BMI), diet, physical exercise, cognitive and social activity, anxiety and depression, and management of cholesterol, diabetes, and blood pressure. Where significant changes were noted, the moderating influence of being in current employment, living with others, and completing the PD-MOOC was tested. RESULTS: Although friend networks contracted marginally during lockdown, no detrimental effects on modifiable dementia risk factors were noted. Anxiety levels and alcohol consumption decreased, there was no change in depression scores, and small but significant improvements were observed in cognitive and physical activity, smoking, diet, and BMI. Stronger improvements in cognitive activity were observed among people who were cohabiting (not living alone) and both cognitive activity and adherence to the MIND diet (Mediterranean-DASH diet Intervention for Neurological Delay) improved more for people who participated in the PD-MOOC. DISCUSSION: Longitudinal data did not show widespread negative effects of COVID-19 lockdown on modifiable dementia risk factors in this sample. The results counter the dominant narratives of universal pandemic-related distress and suggest that engaging at-risk populations in proactive health promotion and education campaigns during lockdown events could be a protective public health strategy.

Transcriptional changes in the stress pathway are related to symptoms in schizophrenia and to mood in schizoaffective disorder.

Altered levels of stress-signalling transcripts have been identified in post-mortem brains of people with schizophrenia, and since stress effects may be expressed throughout the body, there should be similar changes in peripheral cells. However, the extent to which these markers are altered in peripheral white blood cells of people with schizophrenia is not known. Furthermore, how peripheral cortisol and stress-related mRNA are associated with negative symptom severity and emotional states in people with schizophrenia versus schizoaffective disorder has not been determined. Whole blood samples were collected from 86 patients with either schizophrenia or schizoaffective disorder (56 people with schizophrenia and 30 people with schizoaffective disorder), and 77 healthy controls. Total RNA was isolated, cDNA was synthesized, and stress-signalling mRNA levels (for NR3C1, FKBP5, FKBP4, PTGES3 and BAG1) were determined. Stress and symptom severity scores were measured by the Depression, Anxiety and Stress Scale, and the Positive and Negative Syndrome Scale, respectively. We found increased FKBP5 mRNA, Z(156) = 2.5, p = 0.01, decreased FKBP4 mRNA, t(155) = 3.5, p ≤ 0.001, and decreased PTGES3 mRNA, t(153) = 3.0, p ≤ 0.01, in schizophrenia and schizoaffective disorder cohorts combined compared to healthy controls. Stress-related peripheral mRNA levels were differentially correlated with negative emotional states and symptom severity in schizoaffective disorder (ß's = -0.45-0.56, p's = 0.05-0.001) and schizophrenia (ß's = -0.34-0.38, p's = 0.04-0.03), respectively. Therefore, molecules of the stress-signalling pathway appear to differentially contribute to clinical features of schizophrenia versus schizoaffective disorder.

Cannabidiol (CBD) reduces anxiety-related behavior in mice via an FMRP-independent mechanism.

Fragile X Syndrome is a neurodevelopmental disorder which affects intellectual, social and physical development due to mutation of the Fragile X mental retardation 1 (FMR1) gene. The resultant loss of Fragile X mental retardation protein can be modelled by Fmr1 gene knockout (KO) in mice. The current study investigated the behavioural effects of cannabidiol (CBD; a non-psychoactive phytocannabinoid) in male Fmr1 KO mice as a preclinical model for therapeutic discovery. Vehicle or CBD (5 or 20 mg/kg body weight) was administered to adult Fmr1 KO and wild type-like (WT) mice before they were tested in behavioural tasks including: open field (OF), elevated plus maze (EPM), spontaneous alternation, social preference, and passive avoidance tasks. Fmr1 KO mice were hyperlocomotive and hyperexplorative and habituated more slowly to a novel environment compared to control animals. Furthermore, Fmr1 KO mice showed fewer anxiety-related behaviours across tests. Effects of CBD were subtle and limited to the EPM, where CBD decreased the anxiety response of all mice tested. Acute CBD had no impact on locomotion or anxiety-related parameters in the OF. Cognitive performance of Fmr1 KO mice was equivalent to controls and not affected by CBD treatment. Brain concentrations of CBD were equivalent between genotypes, but in animals sacrificed 90 min post-administration, decreased plasma CBD in Fmr1 KO mice compared to WT suggested more rapid clearance of CBD by transgenic animals. Overall, acute CBD at the doses chosen did not selectively normalize behavioural abnormalities in Fmr1 KO mice, but reduced anxiety-like behaviour in both Fmr1 KO and WT mice.

Overexpression of Neuregulin 1 Type III Confers Hippocampal mRNA Alterations and Schizophrenia-Like Behaviors in Mice.

Neuregulin 1 (NRG1) is a schizophrenia candidate gene whose protein product is involved in neuronal migration, survival, and synaptic plasticity via production of specific isoforms. Importantly, NRG1 type III (NRG1 III) mRNA is increased in humans inheriting a schizophrenia risk haplotype for the NRG1 gene (HapICE), and NRG1 protein levels can be elevated in schizophrenia. The nature by which NRG1 type III overexpression results in schizophrenia-like behavior and brain pathology remains unclear, therefore we constructed a transgenic mouse with Nrg1 III overexpression in forebrain neurons (CamKII kinase+). Here, we demonstrate construct validity for this mouse model, as juvenile and adult Nrg1 III transgenic mice exhibit an overexpression of Nrg1 III mRNA and Nrg1 protein in multiple brain regions. Furthermore, Nrg1 III transgenic mice have face validity as they exhibit schizophrenia-relevant behavioral phenotypes including deficits in social preference, impaired fear-associated memory, and reduced prepulse inhibition. Additionally, microarray assay of hippocampal mRNA uncovered transcriptional alterations downstream of Nrg1 III overexpression, including changes in serotonin receptor 2C and angiotensin-converting enzyme. Transgenic mice did not exhibit other schizophrenia-relevant behaviors including hyperactivity, social withdrawal, or an increased vulnerability to the effects of MK-801 malate. Our results indicate that this novel Nrg1 III mouse is valid for modeling potential pathological mechanisms of some schizophrenia-like behaviors, for determining what other neurobiological changes may be downstream of elevated NRG1 III levels and for preclinically testing therapeutic strategies that may be specifically efficacious in patients with the NRG1 (HapICE) risk genotype.

Effects of sex and DTNBP1 (dysbindin) null gene mutation on the developmental GluN2B-GluN2A switch in the mouse cortex and hippocampus.

BACKGROUND: Neurodevelopmental disorders such as autism spectrum disorders and schizophrenia differentially impact males and females and are highly heritable. The ways in which sex and genetic vulnerability influence the pathogenesis of these disorders are not clearly understood. The n-methyl-d-aspartate (NMDA) receptor pathway has been implicated in schizophrenia and autism spectrum disorders and changes dramatically across postnatal development at the level of the GluN2B-GluN2A subunit "switch" (a shift from reliance on GluN2B-containing receptors to reliance on GluN2A-containing receptors). We investigated whether sex and genetic vulnerability (specifically, null mutation of DTNBP1 [dysbindin; a possible susceptibility gene for schizophrenia]) influence the developmental GluN2B-GluN2A switch. METHODS: Subcellular fractionation to enrich for postsynaptic density (PSD), together with Western blotting and kinase assay, were used to investigate the GluN2B-GluN2A switch in the cortex and hippocampus of male and female DTNBP1 null mutant mice and their wild-type littermates. Main effects of sex and DTNBP1 genotype, and interactions with age, were assessed using factorial ANOVA. RESULTS: Sex differences in the GluN2B-GluN2A switch emerged across development at the frontal cortical synapse, in parameters related to GluN2B. Males across genotypes displayed higher GluN2B:GluN2A and GluN2B:GluN1 ratios (p < 0.05 and p < 0.01, respectively), higher GluN2B phosphorylation at Y1472 (p < 0.01), and greater abundance of PLCγ (p < 0.01) and Fyn (p = 0.055) relative to females. In contrast, effects of DTNBP1 were evident exclusively in the hippocampus. The developmental trajectory of GluN2B was disrupted in DTNBP1 null mice (genotype × age interaction p < 0.05), which also displayed an increased synaptic GluN2A:GluN1 ratio (p < 0.05) and decreased PLCγ (p < 0.05) and Fyn (only in females; p < 0.0005) compared to wild-types. CONCLUSIONS: Sex and DTNBP1 mutation influence the GluN2B-GluN2A switch at the synapse in a brain-region-specific fashion involving pY1472-GluN2B, Fyn, and PLCγ. This highlights the possible mechanisms through which risk factors may mediate their effects on vulnerability to disorders of NMDA receptor dysfunction.

Steering and rowing in healthcare: the devolution option.

Claims of"underfunding" notwithstanding, the problems we are experiencing with healthcare in Canada are primarily attributable to a deficiency of governance of our ill-coordinated non-system of health and healthcare services.

Molecular evidence for decreased synaptic efficacy in the postmortem olfactory bulb of individuals with schizophrenia.

Multiple lines of evidence suggest altered synaptic plasticity/connectivity as a pathophysiologic mechanism for various symptom domains of schizophrenia. Olfactory dysfunction, an endophenotype of schizophrenia, reflects altered activity of the olfactory circuitry, which conveys signals from olfactory receptor neurons to the olfactory cortex via synaptic connections in the glomeruli of the olfactory bulb. The olfactory system begins with intranasal olfactory receptor neuron axons synapsing with mitral and tufted cells in the glomeruli of the olfactory bulb, which then convey signals directly to the olfactory cortex. We hypothesized that olfactory dysfunction in schizophrenia is associated with dysregulation of synaptic efficacy in the glomeruli of the olfactory bulb. To test this, we employed semi-quantitative immunohistochemistry to examine the olfactory bulbs of 13 postmortem samples from schizophrenia and their matched control pairs for glomerular expression of 5 pre- and postsynaptic proteins that are involved in the integrity and function of synapses. In the glomeruli of schizophrenia cases compared to their matched controls, we found significant decreases in three presynaptic proteins which play crucial roles in vesicular glutamate transport - synapsin IIa (-18.05%, p=0.019), synaptophysin (-24.08% p=0.0016) and SNAP-25 (-23.9%, p=0.046). Two postsynaptic proteins important for spine formation and glutamatergic signaling were also decreased-spinophilin (-17.40%, p=0.042) and PSD-95 (-34.06%, p=0.015). These findings provide molecular evidence for decreased efficacy of synapses within the olfactory bulb, which may represent a synaptic mechanism underlying olfactory dysfunction in schizophrenia.

The big thing we haven't done yet.

In Healing Medicare, Michael Decter (1994) quotes from a speech made in 1982 by Tommy Douglas: "When we began to plan medicare (35 years previously), we pointed out that it would be in two phases. The first phase would be to remove the financial barrier between those giving the service and those receiving it. The second phase would be to reorganize and revamp the delivery system--and of course, that's the big item. It's the big thing we haven't done yet."

Devolution--a solution for Ontario: could the lone wolf lead the pack?

In response to what we describe as the "accountability gap" in healthcare, nine provinces have embraced the devolution of management responsibility and authority from central government administrations to regional health authorities. Ontario, Canada's most populous province, is the lone wolf. This commentary focuses on the consequences of Ontario's reluctance to adopt devolution. The authors argue that devolution is an important first step in improving the lines of accountability within publicly funded healthcare; however, as a reform initiative, devolution must form part of a series of interlocking initiatives. These complementary reforms include refocusing the debate from funding (money) to governance, clarifying the governance roles of both the federal and provincial governments and developing an incentive- and information-based system that is geared more to rewarding gains in healthcare outcomes as opposed to the delivery of health services. With a new government in Ontario, there is now a window of opportunity to capitalize on the experiences and failures of other provinces and for Ontario to emerge as the leader of the pack, rather than the lone wolf.

Impacts of stress and sex hormones on dopamine neurotransmission in the adolescent brain.

RATIONALE: Adolescence is a developmental period of complex neurobiological change and heightened vulnerability to psychiatric illness. As a result, understanding factors such as sex and stress hormones which drive brain changes in adolescence, and how these factors may influence key neurotransmitter systems implicated in psychiatric illness, is paramount. OBJECTIVES: In this review, we outline the impact of sex and stress hormones at adolescence on dopamine neurotransmission, a signaling pathway which is critical to healthy brain function and has been implicated in psychiatric illness. We review normative developmental changes in dopamine, sex hormone, and stress hormone signaling during adolescence and throughout postnatal life, then highlight the interaction of sex and stress hormones and review their impacts on dopamine neurotransmission in the adolescent brain. RESULTS AND CONCLUSIONS: Adolescence is a time of increased responsiveness to sex and stress hormones, during which the maturing dopaminergic neural circuitry is profoundly influenced by these factors. Testosterone, estrogen, and glucocorticoids interact with each other and have distinct, brain region-specific impacts on dopamine neurotransmission in the adolescent brain, shaping brain maturation and cognitive function in adolescence and adulthood. Some effects of stress/sex hormones on cortical and subcortical dopamine parameters bear similarities with dopaminergic abnormalities seen in schizophrenia, suggesting a possible role for sex/stress hormones at adolescence in influencing risk for psychiatric illness via modulation of dopamine neurotransmission. Stress and sex hormones may prove useful targets in future strategies for modifying risk for psychiatric illness.

Dysregulation of glucocorticoid receptor co-factors FKBP5, BAG1 and PTGES3 in prefrontal cortex in psychotic illness.

Molecular abnormalities within the glucocorticoid receptor (GR) stress signaling pathway may confer, or reflect, susceptibility to stress in schizophrenia and bipolar disorder, but the extent of such abnormalities in the brain is not known. Using RNA-Seq and qPCR in two postmortem cohorts totaling 55 schizophrenia, 34 bipolar disorder and 55 control individuals, we identified increased FKBP5 and PTGES3 mRNA expression, and decreased BAG1 mRNA expression, in the prefrontal cortex in schizophrenia cases relative to controls (68.0% [p < 0.001], 26.0% [p < 0.01] and 12.1% [p < 0.05] respectively). We also observed increased FKBP5 and decreased BAG1 mRNA expression in bipolar disorder (47.5% [p < 0.05] and 14.9% [p < 0.005]). There were no diagnostic differences in steady-state FKBP51 protein levels, nor in HSPA1A, HSP90AA1, DNAJB1 or HSPB1 mRNA levels. GR, co-factor and chaperone mRNA levels were strongly correlated. These results reveal coordinated cortical dysregulation of FKBP5, PTGES3, BAG1 and GR genes within the glucocorticoid signaling pathway in psychotic illness.