Novel Oppositional Defiant Disorder or Conduct Disorder 24 Months After Traumatic Brain Injury in Children and Adolescents.

OBJECTIVE: The authors sought to identify predictive factors of new-onset or novel oppositional defiant disorder or conduct disorder assessed 24 months after traumatic brain injury (TBI). METHODS: Children ages 5 to 14 years who had experienced TBI were recruited from consecutive hospital admissions. Soon after injury, participants were assessed for preinjury characteristics, including psychiatric disorders, socioeconomic status (SES), psychosocial adversity, and family function, and the presence and location of lesions were documented by MRI. Psychiatric outcomes, including novel oppositional defiant disorder or conduct disorder, were assessed 24 months after injury. RESULTS: Of the children without preinjury oppositional defiant disorder, conduct disorder, or disruptive behavior disorder not otherwise specified who were recruited in this study, 165 were included in this sample; 95 of these children returned for the 24-month assessment. Multiple imputation was used to address attrition. The prevalence of novel oppositional defiant disorder or conduct disorder was 23.7 out of 165 (14%). In univariable analyses, novel oppositional defiant disorder or conduct disorder was significantly associated with psychosocial adversity (p=0.049) and frontal white matter lesions (p=0.016) and was marginally but not significantly associated with SES. In the final multipredictor model, frontal white matter lesions were significantly associated with novel oppositional defiant disorder or conduct disorder (p=0.021), and psychosocial adversity score was marginally but not significantly associated with the outcome. The odds ratio of novel oppositional defiant disorder or conduct disorder among the children with versus those without novel depressive disorder was significantly higher for girls than boys (p=0.025), and the odds ratio of novel oppositional defiant disorder or conduct disorder among the children with versus those without novel attention-deficit hyperactivity disorder (ADHD) was significantly higher for boys than girls (p=0.006). CONCLUSION: Approximately 14% of children with TBI developed oppositional defiant disorder or conduct disorder. The risk for novel oppositional defiant disorder or conduct disorder can be understood from a biopsychosocial perspective. Sex differences were evident for comorbid novel depressive disorder and comorbid novel ADHD.

Novel Psychiatric Disorder 6 Months After Traumatic Brain Injury in Children and Adolescents.

OBJECTIVE: To investigate the factors predictive of novel psychiatric disorders in the interval 0-6 months following traumatic brain injury (TBI). METHODS: Children ages 5-14 years consecutively hospitalized for mild to severe TBI at five hospitals were recruited. Participants were evaluated at baseline (soon after injury) for pre-injury characteristics including psychiatric disorders, socioeconomic status (SES), psychosocial adversity, family function, family psychiatric history, and adaptive function. In addition to the psychosocial variables, injury severity and lesion location detected with acquisition of a research MRI were measured to develop a biopsychosocial predictive model for development of novel psychiatric disorders. Psychiatric outcome, including occurrence of a novel psychiatric disorder, was assessed 6 months after the injury. RESULTS: The recruited sample numbered 177 children, and 141 children (80%) returned for the six-month assessment. Of the 141 children, 58 (41%) developed a novel psychiatric disorder. In univariable analyses, novel psychiatric disorder was significantly associated with lower SES, higher psychosocial adversity, and lesions in frontal lobe locations, such as frontal white matter, superior frontal gyrus, inferior frontal gyrus, and orbital gyrus. Multivariable analyses found that novel psychiatric disorder was independently and significantly associated with frontal-lobe white matter, superior frontal gyrus, and orbital gyrus lesions. CONCLUSION: The results demonstrate that occurrence of novel psychiatric disorders following pediatric TBI requiring hospitalization is common and has identifiable psychosocial and specific biological predictors. However, only the lesion predictors were independently related to this adverse psychiatric outcome.

Novel Oppositional Defiant Disorder 6 Months After Traumatic Brain Injury in Children and Adolescents.

OBJECTIVE: The investigators aimed to assess predictive factors of novel oppositional defiant disorder (ODD) among children and adolescents in the first 6 months following traumatic brain injury (TBI). METHODS: Children ages 5-14 years who experienced a TBI were recruited from consecutive admissions to five hospitals. Testing of a biopsychosocial model that may elucidate the development of novel ODD included assessment soon after injury (baseline) of preinjury characteristics, including psychiatric disorders, adaptive function, family function, psychosocial adversity, family psychiatric history, socioeconomic status, injury severity, and postinjury processing speed (which may be a proxy for brain injury). MRI analyses were also conducted to examine potential brain lesions. Psychiatric outcome, including that of novel ODD, was assessed 6 months after the injury. RESULTS: A total of 177 children and adolescents were recruited for the study, and 134 who were without preinjury ODD, conduct disorder, or disruptive behavior disorder not otherwise specified (DBD NOS) returned for the 6-month assessment. Of those who returned 6 months postinjury, 11 (8.2%) developed novel ODD, and none developed novel conduct disorder or DBD NOS. Novel ODD was significantly associated with socioeconomic status, preinjury family functioning, psychosocial adversity, and processing speed. CONCLUSIONS: These findings show that an important minority of children with TBI developed ODD. Psychosocial and injury-related variables, including socioeconomic status, lower family function, psychosocial adversity, and processing speed, significantly increase risk for this outcome.

Novel Oppositional Defiant Disorder 12 Months After Traumatic Brain Injury in Children and Adolescents.

OBJECTIVE: The investigators examined the factors predictive of novel oppositional defiant disorder in the 6-12 months following traumatic brain injury (TBI). METHODS: Children ages 5-14 years old who experienced a TBI were recruited from consecutive admissions to five hospitals. Participants were evaluated soon after injury (baseline) for preinjury characteristics, including psychiatric disorders, adaptive function, family function, psychosocial adversity, family psychiatric history, socioeconomic status, and injury severity, to develop a biopsychosocial predictive model for development of novel oppositional defiant disorder. MRI analyses were conducted to examine potential brain lesions. Psychiatric outcome, including that of novel oppositional defiant disorder, was assessed 12 months after injury. RESULTS: Although 177 children were recruited for the study, 120 children without preinjury oppositional defiant disorder, conduct disorder, or disruptive behavior disorder not otherwise specified (DBD NOS) returned for the 12-month assessment. Of these 120 children, seven (5.8%) exhibited novel oppositional defiant disorder, and none developed conduct disorder or DBD NOS in the 6-12 months postinjury. Novel oppositional defiant disorder was significantly associated with lower socioeconomic status, higher psychosocial adversity, and lower preinjury adaptive functioning. CONCLUSIONS: These results demonstrate that novel oppositional defiant disorder following TBI selectively and negatively affects an identifiable group of children. Both proximal (preinjury adaptive function) and distal (socioeconomic status and psychosocial adversity) psychosocial variables significantly increase risk for this outcome.

Warning SINEs: Alu elements, evolution of the human brain, and the spectrum of neurological disease.

Alu elements are a highly successful family of primate-specific retrotransposons that have fundamentally shaped primate evolution, including the evolution of our own species. Alus play critical roles in the formation of neurological networks and the epigenetic regulation of biochemical processes throughout the central nervous system (CNS), and thus are hypothesized to have contributed to the origin of human cognition. Despite the benefits that Alus provide, deleterious Alu activity is associated with a number of neurological and neurodegenerative disorders. In particular, neurological networks are potentially vulnerable to the epigenetic dysregulation of Alu elements operating across the suite of nuclear-encoded mitochondrial genes that are critical for both mitochondrial and CNS function. Here, we highlight the beneficial neurological aspects of Alu elements as well as their potential to cause disease by disrupting key cellular processes across the CNS. We identify at least 37 neurological and neurodegenerative disorders wherein deleterious Alu activity has been implicated as a contributing factor for the manifestation of disease, and for many of these disorders, this activity is operating on genes that are essential for proper mitochondrial function. We conclude that the epigenetic dysregulation of Alu elements can ultimately disrupt mitochondrial homeostasis within the CNS. This mechanism is a plausible source for the incipient neuronal stress that is consistently observed across a spectrum of sporadic neurological and neurodegenerative disorders.

The biological foundation of the genetic association of TOMM40 with late-onset Alzheimer's disease.

A variable-length poly-T variant in intron 6 of the TOMM40 gene, rs10524523, is associated with risk and age-of-onset of sporadic (late-onset) Alzheimer's disease. In Caucasians, the three predominant alleles at this locus are Short (S), Long (L) or Very long (VL). On an APOE ε3/3 background, the S/VL and VL/VL genotypes are more protective than S/S. The '523 poly-T has regulatory properties, in that the VL poly-T results in higher expression than the S poly-T in luciferase expression systems. The aim of the current work was to identify effects on cellular bioenergetics of increased TOM40 protein expression. MitoTracker Green fluorescence and autophagic vesicle staining was the same in control and over-expressing cells, but TOM40 over-expression was associated with increased expression of TOM20, a preprotein receptor of the TOM complex, the mitochondrial chaperone HSPA9, and PDHE1a, and increased activities of the oxidative phosphorylation complexes I and IV and of the TCA member α-ketoglutaric acid dehydrogenase. Consistent with the complex I findings, respiration was more sensitive to inhibition by rotenone in control cells than in the TOM40 over-expressing cells. In the absence of inhibitors, total cellular ATP, the mitochondrial membrane potential, and respiration were elevated in the over-expressing cells. Spare respiratory capacity was greater in the TOM40 over-expressing cells than in the controls. TOM40 over-expression blocked Ab-elicited decreases in the mitochondrial membrane potential, cellular ATP levels, and cellular viability in the control cells. These data suggest elevated expression of TOM40 may be protective of mitochondrial function.

The Alu neurodegeneration hypothesis: A primate-specific mechanism for neuronal transcription noise, mitochondrial dysfunction, and manifestation of neurodegenerative disease.

It is hypothesized that retrotransposons have played a fundamental role in primate evolution and that enhanced neurologic retrotransposon activity in humans may underlie the origin of higher cognitive function. As a potential consequence of this enhanced activity, it is likely that neurons are susceptible to deleterious retrotransposon pathways that can disrupt mitochondrial function. An example is observed in the TOMM40 gene, encoding a ß-barrel protein critical for mitochondrial preprotein transport. Primate-specific Alu retrotransposons have repeatedly inserted into TOMM40 introns, and at least one variant associated with late-onset Alzheimer's disease originated from an Alu insertion event. We provide evidence of enriched Alu content in mitochondrial genes and postulate that Alus can disrupt mitochondrial populations in neurons, thereby setting the stage for progressive neurologic dysfunction. This Alu neurodegeneration hypothesis is compatible with decades of research and offers a plausible mechanism for the disruption of neuronal mitochondrial homeostasis, ultimately cascading into neurodegenerative disease.

Neuropathologic features of TOMM40 '523 variant on late-life cognitive decline.

INTRODUCTION: The study investigated the role of neuropathologies in the relationship between TOMM40 '523 genotype and late-life cognitive decline. METHODS: Participants were community-dwelling older persons who had annual cognitive assessments and brain autopsies after death. Genotyping used DNA from peripheral blood or postmortem brain tissue. Linear mixed models assessed the extent to which the association of '523 genotype with cognitive decline is attributable to neuropathologies. RESULTS: Relative to ε3/ε3 homozygotes with '523-S/VL or '523-VL/VL genotype, both '523-L carriers and ε3/ε3 homozygotes with '523-S/S genotype had faster cognitive decline. The association of '523-L with cognitive decline was attenuated and no longer significant after controlling for Alzheimer's and other neuropathologies. By contrast, the association of '523-S/S was unchanged. DISCUSSION: There are two distinct TOMM40 '523 signals in relation to late-life cognitive decline. One signal primarily acts through AD and other common neuropathologies, whereas the other operates through a different mechanism.

The developmental expression of the CDK inhibitor p57(kip2) (Cdkn1c) in the early mouse placenta.

p57(kip2) (encoded by the Cdkn1c gene) is a member of the cip/kip family of cyclin-dependent kinase inhibitors that mediates cell cycle arrest in G1, allowing cells to differentiate. In the placenta, p57(kip2) is involved in endoreduplication, formation of trophoblast giant cells, trophoblast invasion, and expansion of placental cell layers. Here, we quantitatively and qualitatively define the cell- and region-specific expression of mouse placental p57(kip2) using laser-capture microdissection, in situ hybridization, and immunohistochemistry. Cdkn1c RNA was quantified by real-time quantitative PCR. Co-expression of Pl1 was used to identify trophoblast giant cells while Tbpba was used to identify spongiotrophoblast cells. Timed sacrifices were also carried out at embryonic days E7.5, E8.5, E9.5, and E12.5 to profile the expression in embryos and their placentas. At E8.5, intense expression of Cdkn1c was seen in invasive TGCs and the ectoplacental cone. Cdkn1c expression was more diffuse and more abundant in the labyrinth that in the junctional zone at both E9.5 and E12.5. Immunohistochemistry revealed robust p57(kip2) staining in trophoblast giant cells and in the ectoplacental cone at E8.5. p57(kip2) protein was seen in giant cells and throughout the labyrinth, although its abundance was reduced in the junctional zone at E9.5, and became more diffuse by E12.5. The early and intense expression in trophoblast giant cells is consistent with a role for p57(kip2) in the invasive phenotype of these cells. Mol. Reprod. Dev. 83: 405-412, 2016. © 2016 Wiley Periodicals, Inc.

Understanding the genetics of APOE and TOMM40 and role of mitochondrial structure and function in clinical pharmacology of Alzheimer's disease.

The methodology of Genome-Wide Association Screening (GWAS) has been applied for more than a decade. Translation to clinical utility has been limited, especially in Alzheimer's Disease (AD). It has become standard practice in the analyses of more than two dozen AD GWAS studies to exclude the apolipoprotein E (APOE) region because of its extraordinary statistical support, unique thus far in complex human diseases. New genes associated with AD are proposed frequently based on SNPs associated with odds ratio (OR) < 1.2. Most of these SNPs are not located within the associated gene exons or introns but are located variable distances away. Often pathologic hypotheses for these genes are presented, with little or no experimental support. By eliminating the analyses of the APOE-TOMM40 linkage disequilibrium region, the relationship and data of several genes that are co-located in that LD region have been largely ignored. Early negative interpretations limited the interest of understanding the genetic data derived from GWAS, particularly regarding the TOMM40 gene. This commentary describes the history and problem(s) in interpretation of the genetic interrogation of the "APOE" region and provides insight into a metabolic mitochondrial basis for the etiology of AD using both APOE and TOMM40 genetics.

Personality Change Due to Traumatic Brain Injury in Children and Adolescents: Neurocognitive Correlates.

Personality change due to traumatic brain injury (PC) in children is an important psychiatric complication of injury and is a form of severe affective dysregulation. This study aimed to examine neurocognitive correlates of PC. The sample included 177 children 5-14 years old with traumatic brain injury who were enrolled from consecutive admissions to five trauma centers. Patients were followed up prospectively at baseline and at 6 months, and they were assessed with semistructured psychiatric interviews. Injury severity, socioeconomic status, and neurocognitive function (measures of attention, processing speed, verbal memory, IQ, verbal working memory, executive function, naming/reading, expressive language, motor speed, and motor inhibition) were assessed with standardized instruments. Unremitted PC was present in 26 (18%) of 141 participants assessed at 6 months postinjury. Attention, processing speed, verbal memory, IQ, and executive function were significantly associated with PC even after socioeconomic status, injury severity, and preinjury attention deficit hyperactivity disorder were controlled. These findings are a first step in characterizing concomitant cognitive impairments associated with PC. The results have implications beyond brain injury to potentially elucidate the neurocognitive symptom complex associated with mood instability regardless of etiology.

Psychiatric disorders in children and adolescents 24 months after mild traumatic brain injury.

This study aimed to better understand the occurrence of novel psychiatric disorders (NPDs) in children with mild traumatic brain injury (mTBI) in relation to preinjury variables, injury-related variables, and concurrent neurocognitive outcome. Eighty-seven children aged 5-14 years who had experienced mTBI were studied from consecutive hospital admissions with semistructured psychiatric interviews soon after injury (baseline). Fifty-four children were reassessed 24 months postinjury. Standardized instruments were used to evaluate injury severity, lesion characteristics, preinjury variables (lifetime psychiatric disorder, family psychiatric history, family function, socioeconomic status, psychosocial adversity, adaptive function, and academic function), and finally, postinjury neurocognitive and adaptive function. At 24 months postinjury, NPDs had occurred in 17 of 54 (31%) participants. NPD at 24 months was related to frontal white matter lesions and was associated with estimated preinjury reading, preinjury adaptive function, and concurrent deficits in reading, processing speed, and adaptive function. These findings extend earlier reports that the psychiatric morbidity after mTBI in children is more common than previously thought, and moreover, it is linked to preinjury individual variables and injury characteristics and is associated with postinjury adaptive and neurocognitive functioning.

Neuropsychological performance of youth with secondary attention-deficit/hyperactivity disorder 6- and 12-months after traumatic brain injury.

The present study compared executive dysfunction among children with attention-deficit/hyperactivity disorder (ADHD) after traumatic brain injury (TBI), also called secondary ADHD (S-ADHD), pre-injury ADHD and children with TBI only (i.e., no ADHD). Youth aged 6-16 years admitted for TBI to five trauma centers were enrolled (n=177) and evaluated with a semi-structured psychiatric interview scheduled on three occasions (within 2 weeks of TBI, i.e., baseline assessment for pre-injury status; 6-months and 12-months post-TBI). This permitted the determination of 6- and 12-month post-injury classifications of membership in three mutually exclusive groups (S-ADHD; pre-injury ADHD; TBI-only). Several executive control measures were administered. Unremitted S-ADHD was present in 17/141 (12%) children at the 6-month assessment, and in 14/125 (11%) children at 12-months post-injury. The study found that children with S-ADHD exhibited deficient working memory, attention, and psychomotor speed as compared to children with pre-injury ADHD. Furthermore, the children with S-ADHD and the children with TBI-only were impaired compared to the children with pre-injury ADHD with regard to planning. No group differences related to response inhibition emerged. Age, but not injury severity, gender, or adaptive functioning was related to executive function outcome. Neuropsychological sequelae distinguish among children who develop S-ADHD following TBI and those with TBI only. Moreover, there appears to be a different pattern of executive control performance in those who develop S-ADHD than in children with pre-injury ADHD suggesting that differences exist in the underlying neural mechanisms that define each disorder, underscoring the need to identify targeted treatment interventions.

African-American TOMM40'523-APOE haplotypes are admixture of West African and Caucasian alleles.

BACKGROUND: Several studies have demonstrated a lower apolipoprotein E4 (APOE ε4) allele frequency in African-Americans, but yet an increased age-related prevalence of AD. An algorithm for prevention clinical trials incorporating TOMM40'523 (Translocase of Outer Mitochondria Membrane) and APOE depends on accurate TOMM40'523-APOE haplotypes. METHODS: We have compared the APOE and TOMM40'523 phased haplotype frequencies of a 9.5 kb TOMM40/APOE genomic region in West African, Caucasian, and African-American cohorts. RESULTS: African-American haplotype frequency scans of poly-T lengths connected in phase with either APOE ε4 or APOE ε3 differ from both West Africans and Caucasians and represent admixture of several distinct West African and Caucasian haplotypes. A new West African TOMM40'523 haplotype, with APOE ε4 connected to a short TOMM40'523 allele, is observed in African-Americans but not Caucasians. CONCLUSION: These data have therapeutic implications for the age of onset risk algorithm estimates and the design of a prevention trial for African-Americans or other mixed ethnic populations.

A single-nucleotide polymorphism tagging set for human drug metabolism and transport.

Interindividual variability in drug response, ranging from no therapeutic benefit to life-threatening adverse reactions, is influenced by variation in genes that control the absorption, distribution, metabolism and excretion of drugs. We genotyped 904 single-nucleotide polymorphisms (SNPs) from 55 such genes in two population samples (European and Japanese) and identified a set of tagging SNPs that represents the common variation in these genes, both known and unknown. Extensive empirical evaluations, including a direct assessment of association with candidate functional SNPs in a new, larger population sample, validated the performance of these tagging SNPs and confirmed their utility for linkage-disequilibrium mapping in pharmacogenetics. The analyses also suggest that rare variation is not amenable to tagging strategies.

Psychiatric disorders in children and adolescents in the first six months after mild traumatic brain injury.

The objective was to assess the nature, rate, predictive factors, and neurocognitive correlates of novel psychiatric disorders (NPD) after mild traumatic brain injury (MTBI). Children age 5-14 years with MTBI (N=87) from consecutive admissions to five trauma centers were enrolled and studied with semistructured psychiatric interviews soon after injury (baseline), and 70 of these children were assessed again 6 months post-injury. Injury severity; lesion characteristics; pre-injury variables, including psychiatric disorder, family psychiatric history, family functioning, socioeconomic status, psychosocial adversity, and adaptive functioning; and post-injury neurocognitive and adaptive functioning measures were assessed with standardized instruments. NPD occurred in 25 of 70 participants (36%) in the first 6 months after injury. NPD at 6 months was predicted by the presence of frontal white-matter lesions on MRI at 3 months post-injury, and was associated with concurrent decrements on neurocognitive indices of processing speed, expressive language, and intellectual functioning. NPD was not predicted by other indices of severity, pre-injury psychosocial variables, estimated pre-injury academic functioning, or adaptive and executive function decrements 6 months post-injury. These findings suggest that short-term psychiatric morbidity associated with MTBI in children and adolescents may be more common than previously thought and may have readily identifiable neuroimaging and neurocognitive correlates.

Psychiatric disorders in children and adolescents six-to-twelve months after mild traumatic brain injury.

The objective of this study was to understand how novel psychiatric disorders (NPD) in children with mild traumatic brain injury (MTBI) are related to pre-injury variables, injury-related variables, and concurrent neurocognitive outcome. A group of 79 children, ages 5 to 14 years, who had experienced MTBI, were studied from consecutive hospital admissions with semistructured psychiatric interviews soon after injury (baseline); 60 children were reassessed 12 months post-injury. Standardized instruments were used to assess injury severity; lesion characteristics; pre-injury variables, including psychiatric disorder, family psychiatric history, family functioning, socioeconomic status, psychosocial adversity, adaptive functioning, and post-injury neurocognitive and adaptive functioning. NPD occurred in 17 of 60 participants (28%) in the 6-12-month interval after injury, with disorders that were significantly associated with socioeconomic status, psychosocial adversity, estimated pre-injury academic functioning, and concurrent deficits in adaptive functioning, academic performance, processing speed, memory, and expressive language. NPD was not significantly associated with pre-injury adaptive functioning, injury severity, family psychiatric history, pre-injury psychiatric disorder, lesion location, gender, or age at injury. These findings suggest that the short-term psychiatric morbidity associated with MTBI in children occurs more commonly than previously reported and is related to both pre-injury social factors and concurrent neurocognitive functioning.

TOMM40 and APOE: Requirements for replication studies of association with age of disease onset and enrichment of a clinical trial.

A number of recent studies have not replicated the association of the translocase of the outer mitochondrial membrane pore subunit (TOMM40) rs10524523 polymorphism, which is in linkage disequilibrium with apolipoprotein E (APOE), with age of onset of Alzheimer's disease (AD). This perspective describes the differences between these later studies and the original experiments. We highlight the necessity for using standardized and informative assessment tools and processes when determining the age of development of AD or AD symptoms, and also stress that this clinical phenotype is best measured reliably in prospective studies during which subjects are monitored over time. This is true when assessing potential biomarkers for age of onset and when assessing the therapeutic potential of medicines that may delay the onset or progression of this disease.

TOMM40 '523 Genotype Distinguishes Patterns of Cognitive Improvement for Executive Function in APOEɛ3 Homozygotes.

BACKGROUND: TOMM40 '523 has been associated with cognitive performance and risk for developing Alzheimer's disease independent of the effect of APOE genotype. Few studies have considered the longitudinal effect of this genotype on change in cognition over time. OBJECTIVE: Our objective was to evaluate the relationship between TOMM40 genotype status and change in cognitive performance in the TOMMORROW study, which was designed to prospectively evaluate an algorithm that includes TOMM40 '523 for genetic risk for conversion to mild cognitive impairment. METHODS: We used latent growth curve models to estimate the effect of TOMM40 allele carrier (short, very long) status on the intercept and slope of change in cognitive performance in four broad cognitive domains (attention, memory, executive function, and language) and a combined overall cognitive score over 30 months. RESULTS: TOMM40 very long allele carriers had significantly lower baseline performance for the combined overall cognitive function score (B = -0.088, p = 0.034) and for the executive function domain score (B = -0.143, p = 0.013). Slopes for TOMM40 very long carriers had significantly greater increases over time for the executive function domain score only. In sensitivity analyses, the results for executive function were observed in participants who remained clinically stable, but not in those who progressed clinically over the study duration. CONCLUSIONS: Our results add to the growing body of evidence that TOMM40, in the absence of APOEɛ4, may contribute to cognitive changes with aging and dementia and support the view that mitochondrial function is an important contributor to Alzheimer's disease risk.