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Psychotropic medication efficacy and tolerability are critical treatment issues faced by individuals with psychiatric disorders and their healthcare providers. For some people, it can take months to years of a trial-and-error process to identify a medication with the ideal efficacy and tolerability profile. Current strategies (e.g. clinical practice guidelines, treatment algorithms) for addressing this issue can be useful at the population level, but often fall short at the individual level. This is, in part, attributed to interindividual variation in genes that are involved in pharmacokinetic (i.e. absorption, distribution, metabolism, elimination) and pharmacodynamic (e.g. receptors, signaling pathways) processes that in large part, determine whether a medication will be efficacious or tolerable. A precision prescribing strategy know as pharmacogenomics (PGx) assesses these genomic variations, and uses it to inform selection and dosing of certain psychotropic medications. In this review, we describe the path that led to the emergence of PGx in psychiatry, the current evidence base and implementation status of PGx in the psychiatric clinic, and finally, the future growth potential of precision psychiatry via the convergence of the PGx-guided strategy with emerging technologies and approaches (i.e. pharmacoepigenomics, pharmacomicrobiomics, pharmacotranscriptomics, pharmacoproteomics, pharmacometabolomics) to personalize treatment of psychiatric disorders.
Many mental disorders, including depression, bipolar disorder and schizophrenia, are associated with poor dietary quality and nutrient intake. There is, however, a deficit of research looking at the relationship between obsessive–compulsive disorder (OCD) severity, nutrient intake and dietary quality.
This study aims to explore the relationship between OCD severity, nutrient intake and dietary quality.
A post hoc regression analysis was conducted with data combined from two separate clinical trials that included 85 adults with diagnosed OCD, using the Structured Clinical Interview for DSM-5. Nutrient intakes were calculated from the Dietary Questionnaire for Epidemiological Studies version 3.2, and dietary quality was scored with the Healthy Eating Index for Australian Adults – 2013.
Nutrient intake in the sample largely aligned with Australian dietary guidelines. Linear regression models adjusted for gender, age and total energy intake showed no significant associations between OCD severity, nutrient intake and dietary quality (all P > 0.05). However, OCD severity was inversely associated with caffeine (β = −15.50, 95% CI −28.88 to −2.11, P = 0.024) and magnesium (β = −6.63, 95% CI −12.72 to −0.53, P = 0.034) intake after adjusting for OCD treatment resistance.
This study showed OCD severity had little effect on nutrient intake and dietary quality. Dietary quality scores were higher than prior studies with healthy samples, but limitations must be noted regarding comparability. Future studies employing larger sample sizes, control groups and more accurate dietary intake measures will further elucidate the relationship between nutrient intake and dietary quality in patients with OCD.
Obsessive–compulsive disorder (OCD) is often challenging to treat and resistant to psychological interventions and prescribed medications. The adjunctive use of nutraceuticals with potential neuromodulatory effects on underpinning pathways such as the glutamatergic and serotonergic systems is one novel approach.
To assess the effectiveness and safety of a purpose-formulated combination of nutraceuticals in treating OCD: N-acetyl cysteine, L-theanine, zinc, magnesium, pyridoxal-5′ phosphate, and selenium.
A 20-week open label proof-of-concept study was undertaken involving 28 participants with treatment-resistant DSM-5-diagnosed OCD, during 2017 to 2020. The primary outcome measure was the Yale-Brown Obsessive–Compulsive Scale (YBOCS), administered every 4 weeks.
An intention-to-treat analysis revealed an estimated mean reduction across time (baseline to week-20) on the YBOCS total score of −7.13 (95% confidence interval = −9.24, −5.01), with a mean reduction of −1.21 points per post-baseline visit (P ≤ .001). At 20-weeks, 23% of the participants were considered “responders” (YBOCS ≥35% reduction and “very much” or “much improved” on the Clinical Global Impression-Improvement scale). Statistically significant improvements were also revealed on all secondary outcomes (eg, mood, anxiety, and quality of life). Notably, treatment response on OCD outcome scales (eg, YBOCS) was greatest in those with lower baseline symptom levels, while response was limited in those with relatively more severe OCD.
While this pilot study lacks placebo-control, the significant time effect in this treatment-resistant OCD population is encouraging and suggests potential utility especially for those with lower symptom levels. Our findings need to be confirmed or refuted via a follow-up placebo-controlled study.
Cigarette smoking is associated with worse cognition and decreased cortical volume and thickness in healthy cohorts. Chronic cigarette smoking is prevalent in schizophrenia spectrum disorders (SSD), but the effects of smoking status on the brain and cognition in SSD are not clear. This study aimed to understand whether cognitive performance and brain morphology differed between smoking and non-smoking individuals with SSD compared to healthy controls.
Data were obtained from the Australian Schizophrenia Research Bank. Cognitive functioning was measured in 299 controls and 455 SSD patients. Cortical volume, thickness and surface area data were analysed from T1-weighted structural scans obtained in a subset of the sample (n = 82 controls, n = 201 SSD). Associations between smoking status (cigarette smoker/non-smoker), cognition and brain morphology were tested using analyses of covariance, including diagnosis as a moderator.
No smoking by diagnosis interactions were evident, and no significant differences were revealed between smokers and non-smokers across any of the variables measured, with the exception of a significantly thinner left posterior cingulate in smokers compared to non-smokers. Several main effects of smoking in the cognitive, volume and thickness analyses were initially significant but did not survive false discovery rate (FDR) correction.
Despite the general absence of significant FDR-corrected findings, trend-level effects suggest the possibility that subtle smoking-related effects exist but were not uncovered due to low statistical power. An investigation of this topic is encouraged to confirm and expand on our findings.
In schizophrenia, relative stability in the magnitude of cognitive deficits across age and illness duration is inconsistent with the evidence of accelerated deterioration in brain regions known to support these functions. These discrepant brain–cognition outcomes may be explained by variability in cognitive reserve (CR), which in neurological disorders has been shown to buffer against brain pathology and minimize its impact on cognitive or clinical indicators of illness.
Age-related change in fluid reasoning, working memory and frontal brain volume, area and thickness were mapped using regression analysis in 214 individuals with schizophrenia or schizoaffective disorder and 168 healthy controls. In patients, these changes were modelled as a function of CR.
Patients showed exaggerated age-related decline in brain structure, but not fluid reasoning compared to controls. In the patient group, no moderation of age-related brain structural change by CR was evident. However, age-related cognitive change was moderated by CR, such that only patients with low CR showed evidence of exaggerated fluid reasoning decline that paralleled the exaggerated age-related deterioration of underpinning brain structures seen in all patients.
In schizophrenia-spectrum illness, CR may negate ageing effects on fluid reasoning by buffering against pathologically exaggerated structural brain deterioration through some form of compensation. CR may represent an important modifier that could explain inconsistencies in brain structure – cognition outcomes in the extant literature.
Objectives: The Wisconsin Card Sorting Test (WCST) is a complex measure of executive function that is frequently employed to investigate the schizophrenia spectrum. The successful completion of the task requires the interaction of multiple intact executive processes, including attention, inhibition, cognitive flexibility, and concept formation. Considerable cognitive heterogeneity exists among the schizophrenia spectrum population, with substantive evidence to support the existence of distinct cognitive phenotypes. The within-group performance heterogeneity of individuals with schizophrenia spectrum disorder (SSD) on the WCST has yet to be investigated. A data-driven cluster analysis was performed to characterise WCST performance heterogeneity. Methods: Hierarchical cluster analysis with k-means optimisation was employed to identify homogenous subgroups in a sample of 210 schizophrenia spectrum participants. Emergent clusters were then compared to each other and a group of 194 healthy controls (HC) on WCST performance and demographic/clinical variables. Results: Three clusters emerged and were validated via altered design iterations. Clusters were deemed to reflect a relatively intact patient subgroup, a moderately impaired patient subgroup, and a severely impaired patient subgroup. Conclusions: Considerable within-group heterogeneity exists on the WCST. Identification of subgroups of patients who exhibit homogenous performance on measures of executive functioning may assist in optimising cognitive interventions. Previous associations found using the WCST among schizophrenia spectrum participants should be reappraised. (JINS, 2019, 25, 750–760)
It is unclear how individual differences in parenting and brain development interact to influence adolescent mental health outcomes. This study examined interactions between structural brain development and observed maternal parenting behavior in the prediction of adolescent depressive symptoms and psychological well-being. Whether findings supported diathesis-stress or differential susceptibility frameworks was tested. Participants completed observed interactions with their mothers during early adolescence (age 13), and the frequency of positive and aggressive maternal behavior were coded. Adolescents also completed structural magnetic resonance imaging scans at three time points: mean ages 13, 17, and 19. Regression models analyzed interactions between maternal behavior and longitudinal brain development in the prediction of late adolescent (age 19) outcomes. Indices designed to distinguish between diathesis-stress and differential susceptibility effects were employed. Results supported differential susceptibility: less thinning of frontal regions was associated with higher well-being in the context of low levels of aggressive maternal behavior, and lower well-being in the context of high levels of aggressive maternal behavior. Findings suggest that reduced frontal cortical thinning during adolescence may underlie increased sensitivity to maternal aggressive behavior for better and worse and highlight the importance of investigating biological vulnerability versus susceptibility.
While previous studies have identified relationships between hippocampal volumes and memory performance in schizophrenia, these relationships are not apparent in healthy individuals. Further, few studies have examined the role of hippocampal subfields in illness-related memory deficits, and no study has examined potential differences across varying illness stages. The current study aimed to investigate whether individuals with early and established psychosis exhibited differential relationships between visuospatial associative memory and hippocampal subfield volumes.
Measurements of visuospatial associative memory performance and grey matter volume were obtained from 52 individuals with a chronic schizophrenia-spectrum disorder, 28 youth with recent-onset psychosis, 52 older healthy controls, and 28 younger healthy controls.
Both chronic and recent-onset patients had impaired visuospatial associative memory performance, however, only chronic patients showed hippocampal subfield volume loss. Both chronic and recent-onset patients demonstrated relationships between visuospatial associative memory performance and hippocampal subfield volumes in the CA4/dentate gyrus and the stratum that were not observed in older healthy controls. There were no group by volume interactions when chronic and recent-onset patients were compared.
The current study extends the findings of previous studies by identifying particular hippocampal subfields, including the hippocampal stratum layers and the dentate gyrus, that appear to be related to visuospatial associative memory ability in individuals with both chronic and first-episode psychosis.
Currently, there is an intense pursuit of pathognomonic markers and diagnostic (‘risk-based’) classifiers of psychiatric conditions. Commonly, the epidemiological prevalence of the condition is not factored into the development of these classifiers. By not adjusting for prevalence, classifiers overestimate the potential of their clinical utility. As valid predictive values have critical implications in public health and allocation of resources, development of clinical classifiers should account for the prevalence of psychiatric conditions in both general and high-risk populations. We suggest that classifiers are most likely to be useful when targeting enriched populations.
Cross-sectional studies suggest that the serotonin transporter promoter region polymorphism (5-HTT gene-linked polymorphic region, 5HTTLPR) moderates the relationship between childhood abuse and major depressive disorder.
To examine whether the 5HTTLPR polymorphism moderates the effect childhood abuse has on 5-year depressive symptom severity trajectories in adulthood.
At 5-year follow-up, DNA from 333 adult primary care attendees was obtained and genotyped for the 5HTTLPR polymorphism. Linear mixed models were used to test for a genotype × childhood abuse interaction effect on 5-year depressive symptom severity trajectories.
After covariate adjustment, homozygous s allele carriers with a history of severe childhood abuse had significantly greater depressive symptom severity at baseline compared with those without a history of severe childhood abuse and this effect persisted throughout the 5-year period of observation.
The 5HTTLPR s/s genotype robustly moderates the effects of severe childhood abuse on depressive symptom severity trajectories in adulthood.
Neuropsychological disturbances have been reported in association with use of the recreational drug “ecstasy,” or 3,4-methylenedioxymethamphetamine (MDMA), but findings have been inconsistent. We performed comprehensive neuropsychological testing examining seven ability domains in 21 MDMA users (MDMA+) and 21 matched control participants (MDMA−). Among MDMA+ participants, median [interquartile range] lifetime MDMA use was 186 [111, 516] doses, with 120 [35–365] days of abstinence. There were no significant group differences in neuropsychological performance, with the exception of the motor speed/dexterity domain in which 43% of MDMA+ were impaired compared with 5% of MDMA− participants (p = .004). Motor impairment differences were not explained by use of other substances and were unrelated to length of abstinence or lifetime number of MDMA doses. Findings provide limited evidence for neuropsychological differences between MDMA+ and MDMA− participants with the exception of motor impairments observed in the MDMA+ group. However, replication of this finding in a larger sample is warranted. (JINS, 2010, 16, 1047–1055.)
While neuropsychological deficits are evident among methamphetamine (meth) addicts, they are often unrelated to meth exposure parameters such as lifetime consumption and length of abstinence. The notion that some meth users develop neuropsychological impairments while others with similar drug exposure do not, suggests that there may be individual differences in vulnerability to the neurotoxic effects of meth. One source of differential vulnerability could come from genotypic variability in metabolic clearance of meth, dependent on the activity of cytochrome P450-2D6 (CYP2D6). We compared neuropsychological performance in 52 individuals with a history of meth dependence according with their CYP2D6 phenotype. All were free of HIV or hepatitis C infection and did not meet dependence criteria for other substances. Extensive metabolizers showed worse overall neuropsychological performance and were three times as likely to be cognitively impaired as intermediate/poor metabolizers. Groups did not differ in their demographic or meth use characteristics, nor did they evidence differences in mood disorder or other substance use. This preliminary study is the first to suggest that efficient meth metabolism is associated with worse neurocognitive outcomes in humans, and implicates the products of oxidative metabolism of meth as a possible source of brain injury. (JINS, 2010, 16, 890–901.)
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