Vulnerability to Stress and Depression Risk Related to Occupational Exposure to Aluminum

Occupational exposure to aluminum was reported to be associated with various neurotoxic effects including cognitive impairment, depression, anxiety, and also Alzheimer’s disease. The purpose of the present study was to evaluate the level of vulnerability to stress in workers exposed to aluminum. The correlation between vulnerability to stress and depression was also investigated. This was a retrospective study that included 135 participants, 99 were exposed to aluminum, and 36 were not exposed to aluminum. Vulnerability to stress and depression was assessed using a self-rating scale developed in-house. Vulnerability to stress was reported in various degrees in a total of 84 participants, 69 (69.70%) participants from the exposed group and 15 (41.67%) participants from the control group. Out of the 84 participants with vulnerability to stress, 51 had depression also. Excellent resistance to stress was reported in 51 out of 135 participants, 30 (30.30%) in the exposed group and 21 (58.33%) in the control group. Out of the 51 participants with excellent resistance to stress, only 2 participants had depression. The results of the present study suggested that exposure to aluminum is correlated with vulnerability to stress. The level of vulnerability to stress is increasing with the level of exposure to aluminum. Furthermore, since vulnerability to stress is correlated with depression, higher exposure to aluminum might be a risk factor for depression.

Association of Increased Amygdala Activity with Stress-Induced Anxiety but not Social Avoidance Behavior in Mice

Chronic stress leads to many psychiatric disorders,including social and anxiety disorders that are associated with over-activation of neurons in the basolateral amygdala(BLA).However,not all individuals develop psychiatric diseases,many showing considerable resilience against stress exposure.Whether BLA neuronal activity is involved in regulating an individual’s vulnerability to stress remains elusive.In this study,using a mouse model of chronic social defeat stress(CSDS),we divided the mice into susceptible and resilient subgroups based on their social interaction behavior.Using in vivo fiber photometry and in vitro patch-clamp recording,we showed that CSDS persistently(after 20 days of recovery from stress)increased BLA neuronal activity in all the mice regardless of their susceptible or resilient nature,although impaired social interaction behavior was only observed in susceptible mice.Increased anxiety-like behavior,on the other hand,was evident in both groups.Notably,the CSDS-induced increase of BLA neuronal activity correlated well with the heightened anxiety-like but not the social avoidance behavior in mice.These findings provide new insight to our understanding of the role of neuronal activity in the amygdala in mediating stress-related psychiatric disorders.