Age-related differences in hippocampal subfield volumes across the human lifespan: A meta-analysis.

The human hippocampus (Hc) is critical for memory function across the lifespan. It is comprised of cytoarchitectonically distinct subfields: dentate gyrus (DG), cornu ammonis sectors (CA) 1-4, and subiculum, each of which may be differentially susceptible to neurodevelopmental and neurodegenerative mechanisms. Identifying age-related differences in Hc subfield volumes can provide insights into neural mechanisms of memory function across the lifespan. Limited evidence suggests that DG and CA3 volumes differ across development while other regions remain relatively stable, and studies of adulthood implicate a downward trend in all subfield volumes with prominent age effects on CA1. Due to differences in methods and limited sampling for any single study, the magnitude of age effects on Hc subfield volumes and their probable lifespan trajectories remain unclear. Here, we conducted a meta-analysis on cross-sectional studies (n = 48,278 participants, ages = 4-94 years) to examine the association between age and Hc subfield volumes in development (n = 11 studies), adulthood (n = 30 studies), and a combined lifespan sample (n = 41 studies) while adjusting estimates for sample sizes. In development, age was positively associated with DG and CA3-4 volumes, whereas in adulthood a negative association was observed with all subfield volumes. Notably, the observed age effects were not different across subfield volumes within each age group. All subfield volumes showed a nonlinear age pattern across the lifespan with DG and CA3-4 volumes showing a more distinct age trajectory as compared to the other subfields. Lastly, among all the study-level variables, only female percentage of the study sample moderated the age effect on CA1 volume: a higher female-to-male ratio in the study sample was linked to the greater negative association between age and CA1 volume. These results document that Hc subfield volumes differ as a function of age offering broader implications for constructing theoretical models of lifespan memory development.

Recurrent Spontaneous Pneumothorax Secondary to Marijuana and Tobacco Abuse.

Primary spontaneous pneumothorax occurs in patients without apparent clinical lung disease, with a higher incidence in tall, thin males between the ages of 10 and 30. Tension pneumothorax is a life-threatening condition that can develop within minutes due to progressive air accumulation in the pleural space; mechanical pressure can lead to significant cardiorespiratory compromise. Tobacco association with a higher incidence of spontaneous pneumothorax has been well documented, but marijuana and spontaneous pneumothorax connection has not been well studied. However, it has been observed that patients who use marijuana and tobacco simultaneously have a higher incidence of spontaneous tension and larger pneumothoraces, as well as longer postoperative stay and higher recurrence than cigarette-only users. We present a case of a 26-year-old young male with a history only significant for excessive tobacco and marijuana smoking who developed multiple recurrent spontaneous pneumothorax and had to undergo right-sided video-assisted thoracoscopic surgery (VATS) with minimally invasive thoracotomy and had a prolonged hospital stay. With our case report, we hope to add to the evidence the effects of combined marijuana and tobacco smoking on bullous lung disease and pneumothorax while emphasizing the importance of conducting a detailed substance use history in patients with spontaneous pneumothorax.