Lipoprotein(a) and risk of cognitive impairment in Black and White Americans: the Reasons for Geographic and Racial Differences in Stroke cohort

Background

Cognitive impairment has a substantial vascular etiology. Higher lipoprotein(a) [Lp(a)] is associated with cardiovascular disease risk, but its association with cognitive function is uncertain. We hypothesized that Lp(a) is a risk factor for cognitive impairment, a relationship that would be modified by race and sex.

Objectives

To study the association of Lp(a) with cognitive impairment in a biracial cohort.

Methods

The Reasons for Geographic and Racial Differences in Stroke (REGARDS) study recruited 30,239 Black and White Americans aged >45 years from 2003 to 2007. After 3.4 years, among participants with normal baseline cognition, baseline Lp(a) was measured in 434 cases of incident cognitive impairment and 557 controls. Cognitive impairment was defined as scores below the sixth percentile based on age, sex, race, and education norms on 2 or 3 components of a 3-test battery administered every 2 years.

Results

Median Lp(a) was higher in Black than in White individuals. Among Black participants, the adjusted odds ratio (OR) of cognitive impairment per SD higher increment Lp(a) was 1.39 (95% CI: 1.05, 1.84). The OR in White participants was 1.03 (95% CI: 0.87, 1.21; P for race difference = .03). The relationship of Lp(a) with cognitive trajectory differed by sex and race. Elevated Lp(a) was associated with worse baseline memory in Black men and a steeper trajectory of verbal fluency decline in Black men than in White men and women.

Conclusion

Higher Lp(a) was associated with increased risk of cognitive impairment in Black but not White individuals. Future studies should evaluate the biological and social mechanisms through which race and Lp(a) interact to increase risk of cognitive impairment.

Effect of detoxification on N3 sleep correlates with brain functional but not structural changes in alcohol use disorder

BACKGROUND

Sleep disturbances are very common in alcohol use disorder (AUD) and contribute to relapse. Detoxification appears to have limited effects on sleep problems. However, inter-individual differences and related brain mechanisms have not been closely examined.

METHODS

We examined N3 sleep and the associated brain functional and structural changes in 30 AUD patients (9 Females, mean age: 42 years) undergoing a 3-week inpatient detoxification. Patients' N3 sleep, resting state functional connectivity (RSFC), grey matter volume (GMV) and negative mood were measured on week 1 and week 3.

RESULTS

AUD patients did not show significant N3 sleep recovery after 3-weeks of detoxification. However, we observed large variability among AUD patients. Inter-individual variations in N3 increases were associated with increases in midline default mode network (DMN) RSFC but not with GMV using a whole-brain approach. Exploratory analyses revealed significant sex by detoxification effects on N3 sleep such that AUD females showed greater N3 increases than AUD males. Further, N3 increases fully mediated the effect of mood improvement on DMN RSFC increases.

CONCLUSIONS

We show a significant relationship between N3 and DMN functional changes in AUD over time/abstinence. The current findings may have clinical implications for monitoring brain recovery in AUD using daily sleep measures, which might help guide individualized treatments. Future investigations on sex differences with a larger sample and with longitudinal data for a longer period of abstinence are needed.

Elevated transferrin saturation in individuals with alcohol use disorder: Association with HFE polymorphism and alcohol withdrawal severity

Iron loading has been consistently reported in those with alcohol use disorder (AUD), but its effect on the clinical course of the disease is not yet fully understood. Here, we conducted a cohort study to examine whether peripheral iron measures, genetic variation in HFE rs1799945 and their interaction differed between 594 inpatient participants with alcohol use disorder (AUD) undergoing detoxification and 472 healthy controls (HC). We also assessed whether HFE rs1799945 was associated with elevated peripheral iron and can serve as a predictor of withdrawal severity. AUD patients showed significantly higher serum transferrin saturation than HC. Within the AUD group, transferrin saturation significantly predicted withdrawal symptoms (CIWA-Ar) and cumulative dose of benzodiazepine treatment during the first week of detoxification, which is an indicator of withdrawal severity. HFE rs1799945 minor allele carriers showed elevated transferrin saturation compared to non-carriers, both in AUD and healthy controls. Exploratory analyses indicated that, within the AUD cohort, HFE rs1799945 predicted CIWA withdrawal scores, and this relationship was significantly mediated by transferrin saturation. We provide evidence that serum transferrin saturation predicts alcohol withdrawal severity in AUD. Moreover, our findings replicated previous studies on elevated serum transferrin saturation in AUD and an involvement of HFE rs1799945 in serum transferrin saturation levels in both AUD and healthy controls. Future studies may use transferrin saturation measures as predictors for treatment or potentially treat iron overload to ameliorate withdrawal symptoms.

Dopamine D1 and D2 receptors are distinctly associated with rest-activity rhythms and drug reward

BACKGROUND

Certain components of rest-activity rhythms such as greater eveningness (delayed phase), physical inactivity (blunted amplitude) and shift work (irregularity) are associated with increased risk for drug use. Dopaminergic (DA) signaling has been hypothesized to mediate the associations, though clinical evidence is lacking.

METHODS

We examined associations between rhythm components and striatal D1 (D1R) and D2/3 receptor (D2/3R) availability in 32 healthy adults (12 female, age: 42.40±12.22) and its relationship to drug reward. Rest-activity rhythms were assessed by one-week actigraphy combined with self-reports. [11C]NNC112 and [11C]raclopride Positron Emission Tomography (PET) scans were conducted to measure D1R and D2/3R availability, respectively. Additionally, self-reported drug-rewarding effects of 60 mg oral methylphenidate were assessed.

RESULTS

We found that delayed rhythm was associated with higher D1R availability in caudate, which was not attributable to sleep loss or 'social jet lag', whereas physical inactivity was associated with higher D2/3R availability in nucleus accumbens (NAc). Delayed rest-activity rhythm, higher caudate D1R and NAc D2/3R availability were associated with greater sensitivity to the rewarding effects of methylphenidate.

CONCLUSION

These findings reveal specific components of rest-activity rhythms associated with striatal D1R, D2/3R availability and drug-rewarding effects. Personalized interventions that target rest-activity rhythms may help prevent and treat substance use disorders.

TRIAL REGISTRATION

ClinicalTrials.gov: NCT03190954FUNDING. This work was accomplished with support from the National Institute on Alcohol Abuse and Alcoholism (ZIAAA000550).

Ketogenic diet reduces alcohol withdrawal symptoms in humans and alcohol intake in rodents

Individuals with alcohol use disorder (AUD) show elevated brain metabolism of acetate at the expense of glucose. We hypothesized that a shift in energy substrates during withdrawal may contribute to withdrawal severity and neurotoxicity in AUD and that a ketogenic diet (KD) may mitigate these effects. We found that inpatients with AUD randomized to receive KD (n = 19) required fewer benzodiazepines during the first week of detoxification, in comparison to those receiving a standard American (SA) diet (n = 14). Over a 3-week treatment, KD compared to SA showed lower "wanting" and increased dorsal anterior cingulate cortex (dACC) reactivity to alcohol cues and altered dACC bioenergetics (i.e., elevated ketones and glutamate and lower neuroinflammatory markers). In a rat model of alcohol dependence, a history of KD reduced alcohol consumption. We provide clinical and preclinical evidence for beneficial effects of KD on managing alcohol withdrawal and on reducing alcohol drinking.

Brain Imaging of Taste Perception in Obesity: a Review

PURPOSE OF REVIEW

We summarize neuroimaging findings related to processing of taste (fat, salt, umami, bitter, and sour) in the brain and how they influence hedonic responses and eating behaviors and their role in obesity.

RECENT FINDINGS

Neuroimaging studies in obese individuals have revealed alterations in reward/motivation, executive control/self-regulation, and limbic/affective circuits that are implicated in food and drug addiction. Psychophysical studies show that sensory properties of food ingredients may be associated with anthropometric and neurocognitive outcomes in obesity. However, few studies have examined the neural correlates of taste and processing of calories and nutrient content in obesity. The literature of neural correlated of bitter, sour, and salty tastes remains sparse in obesity. Most published studies have focused on sweet, followed by fat and umami taste. Studies on calorie processing and its conditioning by preceding taste sensations have started to delineate a dynamic pattern of brain activation associated with appetition. Our expanded understanding of taste processing in the brain from neuroimaging studies is poised to reveal novel prevention and treatment targets to help address overeating and obesity.

Molecular Imaging of Opioid and Dopamine Systems: Insights Into the Pharmacogenetics of Opioid Use Disorders

Opioid use in the United States has steadily risen since the 1990s, along with staggering increases in addiction and overdose fatalities. With this surge in prescription and illicit opioid abuse, it is paramount to understand the genetic risk factors and neuropsychological effects of opioid use disorder (OUD). Polymorphisms disrupting the opioid and dopamine systems have been associated with increased risk for developing substance use disorders. Molecular imaging studies have revealed how these polymorphisms impact the brain and contribute to cognitive and behavioral differences across individuals. Here, we review the current molecular imaging literature to assess how genetic variations in the opioid and dopamine systems affect function in the brain's reward, cognition, and stress pathways, potentially resulting in vulnerabilities to OUD. Continued research of the functional consequences of genetic variants and corresponding alterations in neural mechanisms will inform prevention and treatment of OUD.