Central nervous system stimulants like methamphetamines and cocaine are known to increase the risk of intracranial haemorrhage (ICH) in adults. However, the effects of prenatal methamphetamine exposure on neonatal cerebrovascular outcomes remain underexplored despite its growing prevalence.

To assess whether prenatal methamphetamine exposure increases offspring ICH risk versus unexposed pregnancies, and to compare findings with 3,4-methylenedioxymethamphetamine (MDMA)/opioid exposures, including stratification by gestational age.

This nationwide, population-based cohort study in Taiwan included pregnancies resulting in live births between 2004 and 2018, and followed offspring through 31 December 2019 to examine the association between prenatal exposure to methamphetamines, MDMA or opioids and incident ICH in offspring. The cohort included 53 455 pairs of pregnant women and their first offspring, with 10 691 exposed to illicit drugs and 42 764 matched controls. Cox proportional hazards models estimated adjusted hazard ratios (aHRs), accounting for maternal age, comorbidities, socioeconomic status and other confounders.

Prenatal methamphetamine exposure was associated with a higher risk of ICH in offspring compared with unexposed controls (0.4 v. 0.2%, aHR = 1.72, 95% CI 1.06–2.79). This elevated risk persisted among those exclusively exposed to methamphetamines (aHR = 1.82, 95% CI 1.04–3.29). No statistically significant association was observed for MDMA (0.2 v. 0.2%; aHR = 1.58, 95% CI 0.64–3.93; p = 0.324) or illicit opioids (0.4 v. 0.2%; aHR = 1.43, 95% CI 0.81–2.53; p = 0.214). Stratified analyses showed methamphetamine exposure increased ICH risk among full-term infants (aHR = 4.30, 95% CI 2.08–8.88), with no statistically significant association observed in preterm infants (aHR = 1.00, 95% CI 0.52–1.93).

Prenatal methamphetamine exposure was associated with a higher risk of offspring ICH, particularly among full-term infants. These findings support the importance of efforts to reduce methamphetamine use during pregnancy.

This study aimed to determine if a history of tinnitus is associated with the risk of developing dementia.

A nationwide population-based case–control study including all eligible adults in Taiwan.

A total of 15 686 patients were included in the study, with 7843 individuals making up each of the case and control groups. Patients with a history of tinnitus were associated with a statistically significant higher risk of being diagnosed with dementia before reaching 65 years old (50 years ≤ age <65 years) (adjusted odds ratio 2.68, 95 per cent confidence interval (CI) 1.19–6.05, p = 0.017). No statistical significance was found among those 65 years and older (adjusted odds ratio 1.17, 95 per cent CI 0.90–1.51, p = 0.235).

A history of tinnitus was associated with a 168 per cent increased risk of being diagnosed with dementia in those aged 50–65 years old. This association was not significant in those older than 65 years.