White matter hyperintensities(WMH)is prevalent in the elderly population and is associated with stroke,cognition,gait instability,and neuropsychiatric symptoms.WMH burden usually increases with the growth of age.However,in recent years,there are researches found that WMH is actually dynamic variable.During the development,part of the WMH may regress,accompanied by the slowdown of brain atrophy and cognitive improvement.While,its mechanism,influencing factors and clinical significance remains unclear,and the effective treatment to reverse WMH is not clear.The article reviewed the current studies on the regression of WMH,aiming to provide reference for clinicians to actively perform intervention in the WMH related factors,promote their reversal in the early stage and improve the brain health of patients.

Objective To analyze the status of occupational hazards in key positions of the small and micro book and newspaper printing enterprises in Beijing City. Methods A total of 16 small and micro printing enterprises in Beijing City were selected as the research subjects using the judgment sampling method. The status of occupational hazard was assessed using on-site occupational health investigations. The volatile chemical components in organic solvents such as inks and cleaning agents used in the workplace, the level of chemical hazardous agents in the air, and noise intensity were detected and analyzed. Results A total of 1 105 workers from 16 small and micro printing enterprises were included. The occupational hazard exposure rate was 22.2% (245/1 105), with chemical hazardous agents and noise exposure rates of 13.5% and 22.2%, respectively. The rate of compliance with occupational health training among the head of the enterprise and the occupational health management personnel, the regular detection rate of occupational hazards in last year, and the rate for the occupational health examination in last year were both 100.0%. The rate for annual update of occupational hazard project reporting was 93.8% (15/16). The usage rates of gas mask and noise-proof earplug were 68.8% (11/16) and 50.0% (8/16), respectively. The effectiveness rates of anti-toxic and noise-reduction facilities were 87.5% (14/16) and 62.5% (10/16). The sign setting rates of chemical hazardous agents and noise warning were 93.8% (15/16). Acetone and isopropanol were found in ink and cleaning agents in 15 printing enterprises, while toluene, xylene, and ethylbenzene were found in three, two, and one enterprise, respectively. Benzene, 1,2-dichloroethane, n-hexane, and trichloroethylene were not found in all 16 enterprises. Both the exposure concentration of short term and exposure concentration of time weighted average of the above chemical hazards were lower than the lower limit of quantitation of the detection method in the workplace and work site air among the 16 printing enterprises, and none of concentration was exceeded the national standard. A total of 240 noise work sites were detected, and the national noise-exceeding rate was 11.2%(27/240). Conclusion Noise hazards are prominent in the small and micro printing enterprises in Beijing City, and attention should be paid to the prevention and protection of noise-exposure. The usage rate of personal protective equipment is not high, and the training and on-site supervision management of protective equipment wearing in workers should be strengthened.