Atrophy patterns of hippocampal subfields in T2DM patients with cognitive impairment

ECHDC3 Variant Regulates the Right Hippocampal Microstructural Integrity and Verbal Memory in Type 2 Diabetes Mellitus

ECHDC3 is a risk gene for white matter (WM) hyperintensity and is associated with insulin resistance. This study aimed to investigate whether ECHDC3 variants selectively regulate brain WM microstructures and episodic memory in patients with type 2 diabetes mellitus (T2DM). We enrolled 106 patients with T2DM and 111 healthy controls. A voxel-wise general linear model was employed to explore the interaction effect between ECHDC3 rs11257311 polymorphism and T2DM diagnosis on fractional anisotropy (FA). A linear modulated mediation analysis was conducted to examine the potential of FA value to mediate the influence of T2DM on episodic memory in an ECHDC3-dependent manner. We observed a noteworthy interaction between genotype and diagnosis on FA in the right inferior temporal WM, right anterior limb of the internal capsule, right frontal WM, and the right hippocampus. Modulated mediation analysis revealed a significant ECHDC3 modulation on the T2DM → right hippocampal FA → short-term memory pathway, with only rs11257311 G risk homozygote demonstrating significant mediation effect. Together, our findings provide evidence of ECHDC3 modulating the effect of T2DM on right hippocampal microstructural impairment and short-term memory decline, which might be a neuro-mechanism for T2DM related episodic memory impairment.

Region-specific hippocampal atrophy is correlated with poor glycemic control in type 2 diabetes: a cross-sectional study

To examine the association between prediabetes/type 2 diabetes mellitus (T2DM) and hippocampal subfields and to investigate the effects of glycemic control (HbA1c and FBG)/diabetes duration on the volume of hippocampal subfields in T2DM patients. This cross-sectional study included 268 participants from Tianjin Union Medical Center between August 2019 and July 2022. The participants were divided into three groups: T2DM, prediabetes and no diabetes. All participants underwent brain MRI examination on a 3T MRI scanner. FreeSurfer was performed to segment hippocampus automatically based on T1 MPRAGE images. The relationships between glycemic status/glycemic control/diabetes duration and hippocampal subfield volumes were estimated by multiple linear regression analysis/generalized additive modeling (GAM). Among all participants, 76 (28.36%) had prediabetes, and 96 (35.82%) had T2DM. In multi-adjusted linear regression models, those with prediabetes had a significantly lower volume of bilateral parasubiculum (βright = -5.540; βleft = -6.497). Those with diabetes had lower volume of parasubiculum (βleft = -7.868), presubiculum-head (βleft = -6.244) and fimbria (βleft = -7.187). We did not find relationship between diabetes duration and hippocampal subfield volumes. In stratified analysis, long duration with high FBG related with lower volume of right fimbria (βright = -15.583). Long duration with high HbA1c related with lower volume of presubiculum-head (βright = -19.693), subiculum-head (βright = -28.303), subiculum-body (βleft = -38.599), CA1-head (βright = -62.300, βleft = -47.922), CA1-body (βright = -19.043), CA4-body (βright = -14.392), GC-ML-DG-head (βright = -20.521), GC-ML-DG-body (βright = -16.293, βleft = -12.799), molecular_layer_HP-head (βright = -44.202, βleft = -26.071) and molecular_layer_HP-body, (βright = -31.368), hippocampal_tail (βleft = -80.073). Prediabetes related with lower bilateral parasubiculum volume, and T2DM related with lower left parasubiculum, presubiculum-head and fimbria. T2DM with chronic poor glycemic control had lower volume in multiple hippocampal subregions.

Integrated proteomics and metabolomics analysis of D-pinitol function during hippocampal damage in streptozocin-induced aging-accelerated mice

Purpose

Diabetes can cause hippocampal damage and lead to cognitive impairment. Diabetic cognitive impairment (DCI) is a chronic complication of diabetes associated with a high disability rate; however, its pathogenesis and therapeutic targets are unclear. We aimed to explore the mechanism of hippocampal damage during diabetes and evaluate the potential role of D-pinitol (DP) in protecting hippocampal tissue and improving cognitive dysfunction.

Methods

DP (150 mg/kg/day) was administered intragastrically to streptozocin-induced aging-accelerated mice for 8 weeks. Hippocampal tissues were examined using tandem mass tag (TMT)-based proteomics and liquid chromatography-mass spectrometry (LC-MS)/MS-based non-targeted metabolomic analysis. Differentially expressed proteins (DEPs) and differentially regulated metabolites (DRMs) were screened for further analysis, and some DEPs were verified using western blotting.

Results

Our results showed that 329 proteins had significantly altered hippocampal expression in untreated diabetic mice (DM), which was restored to normal after DP treatment in 72 cases. In total, 207 DRMs were identified in the DM group, and the expression of 32 DRMs was restored to normal post-DP treatment. These proteins and metabolites are involved in metabolic pathways (purine metabolism, arginine and proline metabolism, and histidine metabolism), actin cytoskeleton regulation, oxidative phosphorylation, and Rap1-mediated signaling.

Conclusions

Our study may help to better understand the mechanism of diabetic hippocampal damage and cognitive impairment and suggest a potential therapeutic target.

Effects of hypertension on subcortical nucleus morphological alternations in patients with type 2 diabetes

Objectives

Type 2 diabetes mellitus(T2DM) and hypertension(HTN) are common comorbidities, and known to affect the brain. However, little is known about the effects of the coexisting HTN on brain in T2DM patients. So we aim to investigate the impact of HTN on the subcortical nucleus morphological alternations in T2DM patients.

Materials & methods

This work was registered by the clinicaltrials.gov (grant number NCT03564431). We recruited a total of 92 participants, comprising 36 only T2DM patients, 28 T2DM patients with HTN(T2DMH) and 28 healthy controls(HCs) in our study. All clinical indicators were assessed and brain image data was collected for each participant. Voxel-based morphometry(VBM), automatic volume and vertex-based shape analyses were used to determine the subcortical nucleus alternations from each participant's 3D-T1 brain images and evaluate the relationship between the alternations and clinical indicators.

Results

T2DMH patients exhibited volumetric reduction and morphological alterations in thalamus compared to T2DM patients, whereas T2DM patients did not demonstrate any significant subcortical alterations compared to HCs. Furthermore, negative correlations have been found between thalamic alternations and the duration of HTN in T2DMH patients.

Conclusion

Our results revealed that HTN may exacerbate subcortical nucleus alternations in T2DM patients, which highlighted the importance of HTN management in T2DM patients to prevent further damage to the brain health.

The association of prediabetes and type 2 diabetes with hippocampal subfields volume: The Maastricht study

AIMS/HYPOTHESIS

We investigated whether prediabetes, type 2 diabetes, and continuous measures of hyperglycemia are associated with tissue volume differences in specific subfields of the hippocampus.

METHODS

We used cross-sectional data from 4,724 participants (58.7 ± 8.5 years, 51.5% women) of The Maastricht Study, a population-based prospective cohort. Glucose metabolism status was assessed with an oral glucose tolerance test, and defined as type 2 diabetes (n = 869), prediabetes (n = 671), or normal glucose metabolism (n = 3184). We extracted 12 hippocampal subfield volumes per hemisphere with FreeSurfer v6.0 using T1w and FLAIR 3T MRI images. We used multiple linear regression and linear trend analysis, and adjusted for total intracranial volume, demographic, lifestyle, and cardiovascular risk factors.

RESULTS

Type 2 diabetes was significantly associated with smaller volumes in the hippocampal subfield fimbria (standardized beta coefficient ± standard error (β ± SE) = -0.195 ± 0.04, p-value < 0.001), the hippocampus proper, i.e. Cornu Ammonis (CA) 1, CA2/3, CA4, dentate gyrus, subiculum and presubiculum (β ± SE < -0.105 ± 0.04, p-value < 0.006); as well as the hippocampal tail (β ± SE = -0.162 ± 0.04, p-value < 0.001). Prediabetes showed no significant associations. However, linear trend analysis indicated a dose-response relation from normal glucose metabolism, to prediabetes, to type 2 diabetes. Multiple continuous measures of hyperglycemia were associated with smaller volumes of the subfields fimbria (β ± SE < -0.010 ± 0.011, p-value < 0.001), dentate gyrus (β ± SE < -0.013 ± 0.010, p-value < 0.002), CA3 (β ± SE < -0.014 ± 0.011, p-value < 0.001), and tail (β ± SE < -0.006 ± 0.012, p-value < 0.003).

CONCLUSIONS/INTERPRETATION

Type 2 diabetes and measures of hyperglycemia are associated with hippocampal subfield atrophy, independently of lifestyle and cardiovascular risk factors. We found evidence for a dose-response relationship from normal glucose metabolism, to prediabetes, to type 2 diabetes. Prediabetes stages could give a window of opportunity for the early prevention of brain disease.

Longitudinal real world correlation study of blood pressure and novel features of cerebral magnetic resonance angiography by artificial intelligence analysis on elderly cognitive impairment

Objective

This study aims to investigate novel clinical risk factors for cognitive impairment (CI) in elderly.

Methods

A total of 3221 patients (259 patients with CI and 2,962 subjects without CI) were recruited into this nested case-control study who underwent cerebral magnetic resonance angiography (MRA) from 2007 to 2021. All of the clinical data with MRA imaging were recorded followed by standardization processing blindly. The maximum stenosis score of the posterior circulatory artery, including the basilar artery, and bilateral posterior cerebral artery (PCA), was calculated by the cerebral MRA automatic quantitative analysis method. Logistic regression (LR) analysis was used to evaluate the relationship between risk factors and CI. Four machine learning approaches, including LR, decision tree (DT), random forest (RF), and support vector machine (SVM), employing 5-fold cross-validation were used to establish CI predictive models.

Results

After matching with age and gender, 208 CI patients and 208 control subjects were finalized the follow-up (3.46 ± 3.19 years) with mean age at 84.47 ± 6.50 years old. Pulse pressure (PP) in first tertile (<58 mmHg) (OR 0.588, 95% confidence interval (CI): 0.362-0.955) was associated with a decreased risk for CI, and ≥50% stenosis of the left PCA (OR 2.854, 95% CI: 1.387-5.872) was associated with an increased risk for CI after adjusting for body mass index, myocardial infarction, and stroke history. Based on the means of various blood pressure (BP) parameters, the performance of the LR, DT, RF and SVM models accurately predicted CI (AUC 0.740, 0.786, 0.762, and 0.753, respectively) after adding the stenosis score of posterior circulatory artery.

Conclusion

Elderly with low pulse differential pressure may have lower risk for cognitive impairment. The hybrid model combined with the stenosis score of posterior circulatory artery, clinical indicators, and the means of various BP parameters can effectively predict the risk of CI in elderly individuals.

Molecular mechanisms underlying hyperglycemia associated cognitive decline

Diabetes mellitus (DM) is a metabolic disease characterized by chronic hyperglycemia. DM can lead to a number of secondary complications affecting multiple organs in the body including the eyes, kidney, heart, and brain. The most common effect of hyperglycemia on the brain is cognitive decline. It has been estimated that 20-70% of people with DM have cognitive deficits. High blood sugar affects key brain areas involved in learning, memory, and spatial navigation, and the structural complexity of the brain has made it prone to a variety of pathological disorders, including T2DM. Studies have reported that cognitive decline can occur in people with diabetes, which could go undetected for several years. Moreover, studies on brain imaging suggest extensive effects on different brain regions in patients with T2D. It remains unclear whether diabetes-associated cognitive decline is a consequence of hyperglycemia or a complication that co-occurs with T2D. The exact mechanism underlying cognitive impairment in diabetes is complex; however, impaired glucose metabolism and abnormal insulin function are thought to play important roles. In this review, we have tried to summarize the effect of hyperglycemia on the brain structure and functions, along with the potential mechanisms underlying T2DM-associated cognitive decline.

Quantitative Electroencephalography Findings in Patients With Diabetes Mellitus

Objective. Diabetes mellitus (DM) causes structural central nervous system (CNS) impairment, and this situation can be detected by quantitative electroencephalography (QEEG) findings before cognitive impairment is clinically observed. The main aim of this study is to uncover the effect of DM on brain function. Since QEEG reflects the CNS functioning, particularly in cognitive aspects, we expected electrophysiological clues to be found for prevention and follow-up in DM-related cognitive decline. Since a majority of the psychiatric population have cognitive dysfunction, we have given particular attention to those people. It was stated that a decrease was observed in the posterior cortical alpha power due to the hippocampal atrophy by several previous studies and we hypothesize that decreased alpha power will be observed also in DM. Methods. This study included 2094 psychiatric patients, 207 of whom were diagnosed with DM and 1887 of whom were not diagnosed with DM, and QEEG recordings were performed. Eyes-closed electroencephalography data were segmented into consecutive 2 s epochs. Fourier analysis was performed by averaging across 2 s epochs without artifacts. The absolute alpha power in the occipital regions (O1 and O2) of patients with and without DM was compared. Results. In the DM group, a decrease in the absolute alpha, alpha 1, and alpha 2 power in O1 and O2 was observed in comparison with the control group. It was determined that the type of psychiatric diagnosis did not affect QEEG findings. Conclusion. The decrease in absolute alpha power observed in patients diagnosed with DM may be related to the CNS impairment in DM. QEEG findings in DM can be useful while monitoring the CNS impairment, diagnosing DM-related dementia, in the follow-up of the cognitive process, constructing the protocols for electrophysiological interventions like neurofeedback and transcranial magnetic stimulation and monitoring the response to treatment.

Paeoniflorin ameliorates cognitive impairment in Parkinson's disease via JNK/p53 signaling

Paeoniflorin (PF) has numerous benefits, including anti-inflammatory and anti-apoptosis effects. However, it is not clear if it has neuroprotective effects against cognitive impairment (CI) in Parkinson's disease (PD). Through network pharmacology, we identified probable targets as well as signal pathways through which PF might affect CI in PD. Then, we experimentally validated our findings. The core genes of the protein-protein interactions (PPI) network include MAPK8 (JNK), TP53, CASP3 (caspase-3), postsynaptic density protein-95 (PSD-95) and synaptophysin (SYN). Pathway enrichment analysis revealed that genes involved in apoptosis and mitogen-activated protein kinase (MAPK) signaling were significantly enriched. Because JNK is a key mediator of p53-induced apoptosis, we wondered if JNK/p53 pathway influences the effects of PF against apoptosis in mouse model of PD. Molecular docking analysis showed that PF had good affinity for JNK/p53. The results of the experiments indicated that PF ameliorated behavioral impairments and upregulated the expression of the dopamine (DA) neurons, suppressed cell apoptosis in substantia nigra pars compacta (SNpc) of PD. Additionally, PF improved 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced neuronal injury by inhibiting apoptosis in hippocampal neurons of the CA1 and CA3, and upregulating PSD-95 as well as SYN protein levels. Similar protective effects were observed upon JNK/p53 pathway inhibition using SP600125. Overall, PF improved CI in PD by inhibiting JNK/p53 pathway.

Common pathways in dementia and diabetic retinopathy: understanding the mechanisms of diabetes-related cognitive decline

Type 2 diabetes (T2D) is associated with multiple comorbidities, including diabetic retinopathy (DR) and cognitive decline, and T2D patients have a significantly higher risk of developing Alzheimer's disease (AD). Both DR and AD are characterized by a number of pathological mechanisms that coalesce around the neurovascular unit, including neuroinflammation and degeneration, vascular degeneration, and glial activation. Chronic hyperglycemia and insulin resistance also play a significant role, leading to activation of pathological mechanisms such as increased oxidative stress and the accumulation of advanced glycation end-products (AGEs). Understanding these common pathways and the degree to which they occur simultaneously in the brain and retina during diabetes will provide avenues to identify T2D patients at risk of cognitive decline.

Free Triiodothyronine Levels are Related to Executive Function and Scene Memory in Type 2 Diabetes Mellitus Patients Without Diagnosed Thyroid Diseases

PURPOSE

We aim to determine the role of free triiodothyronine (FT3), the main active ingredient of thyroid hormones (THs), in type 2 diabetes mellitus (T2DM) patients with mild cognitive impairment (MCI).

PATIENTS AND METHODS

A total of 255 T2DM patients without diagnosed thyroid diseases were recruited and divided into MCI group and healthy cognition group. Neuropsychological functions were observed by multidimensional cognitive function scales in including MoCA, Digit Span Test (DST), Verbal Fluency Test (VFT), Clock drawing test (CDT), Trail Making Test (TMT) A and B, Instantaneously Recalled Auditory Verbal Learning Test (AVLT-IR), Delayed Recalled Auditory Verbal Learning Test (AVLT-DR) and Logical Memory Test (LMT). Correlation and logistic regression analyses were performed to explore the association between FT3 and diabetic cognitive dysfunction.

RESULTS

Compared with 147 normal cognition patients, 108 MCI patients exhibited lower FT3 and higher HOMA-IR. FT3 level was not only positively correlated with MoCA scores, but DST, VFT and LMT, while negatively associated with TMTB. Furthermore, there is a negative association between FT3 and HOMA-IR. Logistic regression showed that decreased FT3 is a risk factor of MCI in T2DM patients. Although FT3 is not the risk factor of MCI after homeostasis model assessment of insulin resistance (HOMA-IR) was entered as an independent variable, lower FT3 is associated with VFT and LMT adjusted by age, education, BMI, DM duration, HBP duration, smoking, HbA1c and HOMA-IR.

CONCLUSION

Lower FT3 levels may involve in MCI, especially for executive function and scene memory in T2DM patients without diagnosed thyroid diseases.

Identifying Type 2 Diabetic Brains by Investigating Disease-Related Structural Changes in Magnetic Resonance Imaging

Diabetes with high blood glucose levels may damage the brain nerves and thus increase the risk of dementia. Previous studies have shown that dementia can be reflected in altered brain structure, facilitating computer-aided diagnosis of brain diseases based on structural magnetic resonance imaging (MRI). However, type 2 diabetes mellitus (T2DM)-mediated changes in the brain structures have not yet been studied, and only a few studies have focused on the use of brain MRI for automated diagnosis of T2DM. Hence, identifying MRI biomarkers is essential to evaluate the association between changes in brain structure and T2DM as well as cognitive impairment (CI). The present study aims to investigate four methods to extract features from MRI, characterize imaging biomarkers, as well as identify subjects with T2DM and CI.

Effects of INSR genetic polymorphism on hippocampal volume and episodic memory in chinese type 2 diabetes

AIMS

We aimed to investigate the effect of the type 2 diabetes-specific insulin/IGF signaling genetic variants on the hippocampal volume and their relationships with episodic memory in Chinese patients with type 2 diabetes.

METHODS

Analysis of variance was used to evaluate the genotype-by-diagnosis interaction effect on hippocampal volume in Chinese participants (109 patients with type 2 diabetes, 116 healthy controls). Mediation analysis was performed to test whether the hippocampal volume would mediate the association between genotype and episodic memory in patients with type 2 diabetes.

RESULTS

INSR (rs8101064) exhibited a significant genotype-by-diagnosis interaction effect on the bilateral hippocampal volumes (left, P = 0.020; right, P = 0.004, P_FDR < 0.05). The T allele carriers exhibited smaller bilateral hippocampal volumes than the CC homozygotes in patients with type 2 diabetes (left, P = 0.004; right, P = 0.002). Mediation analysis revealed the significant mediation effect of the left hippocampal volume on the association between INSR (rs8101064) genetic polymorphism and the short- and long-term memory scores in patients with type 2 diabetes (short-term memory: 95% CI, -2.716, -0.266; long-term memory: 95% CI, -0.823, -0.103).

CONCLUSIONS

Hyperglycemia exposure and INSR (rs8101064) genetic polymorphism had an interaction effect on the hippocampal volume, and the T allele of the INSR (rs8101064) may serve as a risk factor for the decreased hippocampal volume in Chinese patients with type 2 diabetes. The left hippocampal volume mediated the effect of INSR (rs8101064) genetic polymorphism on episodic memory in Chinese patients with type 2 diabetes, which provided a biological pathway for understanding how the INSR (rs8101064) genetic polymorphism affects episodic memory in type 2 diabetes.

Hippocampal subfields atrophy contribute more to cognitive impairment in middle-aged patients with type 2 diabetes rather than microvascular lesions

AIMS

Neurodegeneration and microvascular lesions are related to cognitive impairment in type 2 diabetes mellitus (T2DM). We aimed to use the volume of hippocampal subfields and the burden of white matter hyperintensities (WMH) as neurodegeneration and microangiopathy markers, respectively, to investigate their potential associations with cognitive impairment in T2DM patients.

METHODS

A total of 76 T2DM patients and 45 neurologically unimpaired normal controls were enrolled between February 2016 to August 2018. All participants underwent structural magnetic resonance imaging (MRI) and Montreal Cognitive Assessment (MoCA). The T2DM patients were divided into the T2DM without mild cognitive impairment (T2noMCI) group (n = 44) and the T2DM with mild cognitive impairment (T2MCI) group (n = 32) according to MoCA scores. We used automatic brain segmentation and quantitative technique to assess the volume of twelve hippocampal subfields and WMH on MRI. We used age, sex, education, and total intracranial volume as our covariates and the Bonferroni method for multiple comparison correction.

RESULTS

Both the T2MCI group and T2noMCI group showed significant hippocampal subfields atrophy compared to the controls, which were mainly in the left hippocampal tail, left CA1, bilateral molecular layer, bilateral dentate gyrus, and bilateral CA4 (all p < 0.0042). No significant differences in the volume of total WMH, deep-WMH, and periventricular-WMH were found among the three groups. The HbA1c levels were significantly negatively correlated with hippocampal atrophy, and the MoCA scores were positively correlated with bilateral hippocampal volume in T2DM patients and all samples. Mediation analyses demonstrated that the association of HbA1c levels with cognitive function was mediated by hippocampal subfields volume.

CONCLUSION

Widespread hippocampal atrophies across the subfields have been found in middle-aged T2DM patients, which was positively correlated with the MoCA scores and negatively correlated with the HbA1c levels. The association of HbA1c levels with cognitive function was mediated by some crucial hippocampal subfields volume. In middle-aged patients with T2DM, the neurodegeneration is more strongly associated with cognitive impairment than microvascular lesions. Trail Registeration This study was registered on Clinical-Trails.gov (NCT02738671).

Deviations in Hippocampal Subregion in Older Adults With Cognitive Frailty

BACKGROUND

Cognitive frailty is a particular state of cognitive vulnerability toward dementia with neuropathological hallmarks. The hippocampus is a complex, heterogeneous structure closely relates to the cognitive impairment in elderly which is composed of 12 subregions. Atrophy of these subregions has been implicated in a variety of neurodegenerative diseases. The aim of this study was to explore the changes in hippocampal subregions in older adults with cognitive frailty and the relationship between subregions and cognitive impairment as well as physical frailty.

METHODS

Twenty-six older adults with cognitive frailty and 26 matched healthy controls were included in this study. Cognitive function was evaluated by the Montreal Cognitive Assessment (MoCA) scale (Fuzhou version) and Wechsler Memory Scale-Revised Chinese version (WMS-RC), while physical frailty was tested with the Chinese version of the Edmonton Frailty Scale (EFS) and grip strength. The volume of the hippocampal subregions was measured with structural brain magnetic resonance imaging. Partial correlation analysis was carried out between the volumes of hippocampal subregions and MoCA scores, Wechsler's Memory Quotient and physical frailty indexes.

RESULTS

A significant volume decrease was found in six hippocampal subregions, including the bilateral presubiculum, the left parasubiculum, molecular layer of the hippocampus proper (molecular layer of the HP), and hippocampal amygdala transition area (HATA), and the right cornu ammonis subfield 1 (CA1) area, in older adults with cognitive frailty, while the proportion of brain parenchyma and total number of white matter fibers were lower than those in the healthy controls. Positive correlations were found between Wechsler's Memory Quotient and the size of the left molecular layer of the HP and HATA and the right presubiculum. The sizes of the left presubiculum, molecular of the layer HP, and HATA and right CA1 and presubiculum were found to be positively correlated with MoCA score. The sizes of the left parasubiculum, molecular layer of the HP and HATA were found to be negatively correlated with the physical frailty index.

CONCLUSION

Significant volume decrease occurs in hippocampal subregions of older adults with cognitive frailty, and these changes are correlated with cognitive impairment and physical frailty. Therefore, the atrophy of hippocampal subregions could participate in the pathological progression of cognitive frailty.

Multimodal hippocampal and amygdala subfield volumetry in polygenic risk for Alzheimer's disease

Preclinical models of Alzheimer's disease (AD) suggest that volumetric reductions in medial temporal lobe (MTL) structures manifest before clinical onset. AD polygenic risk scores (PRSs) are further linked to reduced MTL volumes (the hippocampus/amygdala); however, the relationship between the PRS and specific subregions remains unclear. We determine the relationship between the AD-PRSs and MTL subregions in a large sample of young participants (N = 730, aged 22–35 years) using a multimodal (T1w/T2w) approach. We first demonstrate that the PRSs for the hippocampus/amygdala predict their respective volumes and specific hippocampal subregions (pFDR < 0.05). We further observe negative relationships between the AD-PRSs and whole hippocampal/amygdala volumes. Critically, we demonstrate novel associations between the AD-PRSs and specific hippocampal subfields such as CA1 (β = −0.096, pFDR = 0.045) and the fissure (β = −0.101, pFDR = 0.041). We provide evidence that the AD-PRS is linked to specific MTL subfields decades before AD onset. This may help inform preclinical models of AD risk, providing additional specificity for intervention and further insight into mechanisms by which common AD variants confer susceptibility.

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Polygenic risk for Alzheimer's disease (AD-PRS) explains significant proportion of AD.

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AD-PRS also linked to hippocampus and amygdala volume.

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AD-PRS is negatively associated with specific hippocampal subfields.

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Polygenic AD models help us understand genetic contributions to medial temporal lobe nuclei.