👤 Baris Akinci

Sex differences in Alzheimer disease (AD) neuropathology have not been examined extensively across multiple pathological constructs within broadly representative samples. To examine sex differences in neuroimaging biomarkers of AD-related pathologies in a racially and ethnically diverse cohort. Data for this cross-sectional study were collected from a community-based sample of adults without cognitive impairment aged 60 to 69 years in New York City from March 1, 2016, to September 31, 2022, and analyzed in March 2025. The primary exposure was self-reported sex (women or men). The outcomes were global amyloid burden measured with florbetaben labeled with fludeoxyglucose 18 (18F) positron emission tomography (PET), tau burden in Braak stages I to VI measured with 18F-MK-6240 PET, and magnetic resonance imaging (MRI)-derived AD signature cortical thickness and white matter hyperintensity volumes. Linear regression analyses were performed to examine sex differences in the outcomes. Covariates included demographics, APOE ε4 status, and vascular health-related factors. Sex × age, sex × APOE ε4, and sex × race and ethnicity interactions were additionally examined on the outcomes. False discovery rate (FDR) correction for multiple comparisons were also performed. A total of 503 participants (mean [SD] age, 64.6 [2.8] years; 321 [63.8%] women; 305 [60.6%] Hispanic, 120 [23.9%] non-Hispanic Black, and 78 [15.5%] non-Hispanic White) with Aβ PET, MRI (n = 501), and tau PET (n = 355) data were studied. Compared with men, women had greater amyloid burden (B = 0.05; 95% CI, 0.02-0.07; P < .001), Braak stages III and IV (B = 0.05; 95% CI, 0.02-0.08; P = .003) and Braak stages V and VI (B = 0.09; 95% CI, 0.06-0.12; P < .001) tau burden, and AD signature thickness (B = 0.04; 95% CI, 0.02-0.05; P < .001). A significant sex × APOE ε4 interaction was observed, with women showing greater Braak stages I and II (B = 0.15; 95% CI, 0.04-0.25; P = .006) and Braak stages III and IV (B = 0.08; 95% CI, 0.02-0.14; P = .01) tau burden than men among APOE ε4 carriers. All findings remained statistically significant after FDR correction. No significant sex × age or sex × race and ethnicity interactions were observed on any outcome. This cross-sectional study of community-based adults found greater AD pathology yet better preserved structural brain integrity in women compared with men. Sex differences in tau burden across early to middle Braak stages were more pronounced among APOE ε4 carriers compared with noncarriers. These findings were not modified by age or race and ethnicity. Overall, the results underscore sex-specific distinctions in AD pathology burden and brain structure at the cross-sectional level. Show less

Partial lipodystrophy (PL) is a rare disease characterized by selective loss of subcutaneous fat. To evaluate changes in apolipoproteins, hepatokines, hormones, appetite regulators, and inflammatory markers in patients with PL treated with leptin, assess postprandial metabolism and 24-hour dynamics, and identify predictors of hepatic and metabolic response to therapy. We studied 19 subjects from our previous clinical study (NCT01679197), which investigated the effect of leptin on metabolic dysfunction-associated steatohepatitis associated with PL. A mixed-meal test was performed in a subgroup of 14 patients, and paired 24-hour frequent sampling with standardized meals was completed in 5 individuals. Leptin treatment led to reductions in apolipoproteins B, CII, CIII, and E ( Leptin therapy modulates lipid metabolism, postprandial glucose regulation, and appetite signaling in patients with PL, with responses associated with metabolic parameters and carbohydrate intake. Show less

A patient with atypical partial lipodystrophy who had a transient initial response to metreleptin experienced acute worsening of her metabolic state when neutralizing antibodies against metreleptin appeared. Because her metabolic status continued to deteriorate, a therapeutic trial with melanocortin-4 receptor agonist setmelanotide, that is believed to function downstream from leptin receptor in the leptin signaling system, was undertaken in an effort to improve her metabolic status for the first time in a patient with lipodystrophy. To achieve this, a compassionate use (investigational new drug application; IND) was initiated (NCT03262610). Glucose control, body fat by dual-energy X-ray absorptiometry and MRI, and liver fat by proton density fat fraction were monitored. Daily hunger scores were assessed by patient filled questionnaires. Although there was a slight decrease in hunger scales and visceral fat, stimulating melanocortin-4 receptor by setmelanotide did not result in any other metabolic benefit such as improvement of hypertriglyceridemia or diabetes control as desired. Targeting melanocortin-4 receptor to regulate energy metabolism in this setting was not sufficient to obtain a significant metabolic benefit. However, complex features of our case make it difficult to generalize these observations to all cases of lipodystrophy. It is still possible that melanocortin-4 receptor agonistic action may offer some therapeutic benefits in leptin-deficient patients. A patient with atypical lipodystrophy with an initial benefit with metreleptin therapy developed neutralizing antibodies to metreleptin (Nab-leptin), which led to substantial worsening in metabolic control. The neutralizing activity in her serum persisted for longer than 3 years. Whether the worsening in her metabolic state was truly caused by the development of Nab-leptin cannot be fully ascertained, but there was a temporal relationship. The experience noted in our patient at least raises the possibility for concern for substantial metabolic worsening upon emergence and persistence of Nab-leptin. Further studies of cases where Nab-leptin is detected and better assay systems to detect and characterize Nab-leptin are needed. The use of setmelanotide, a selective MC4R agonist targeting specific neurons downstream from the leptin receptor activation, was not effective in restoring metabolic control in this complex patient with presumed diminished leptin action due to Nab-leptin. Although stimulating the MC4R pathway was not sufficient to obtain a significant metabolic benefit in lowering triglycerides and helping with her insulin resistance as was noted with metreleptin earlier, there was a mild reduction in reported food intake and appetite. Complex features of our case make it difficult to generalize our observation to all leptin-deficient patients. It is possible that some leptin-deficient patients (especially those who need primarily control of food intake) may still theoretically benefit from MC4R agonistic action, and further studies in carefully selected patients may help to tease out the differential pathways of metabolic regulation by the complex network of leptin signaling system. Show less