Perhaps you should try some spelling variations:
decrease treg » decrease the (Expand search), decrease their (Expand search)
treg affected » trees affected (Expand search), are affected (Expand search), area affected (Expand search)
decrease any » decrease and (Expand search), decreases and (Expand search), decreased and (Expand search)
any decrease » and decrease (Expand search), can decrease (Expand search), on decrease (Expand search)
decrease may » decrease at (Expand search), decrease by (Expand search), decrease human (Expand search)
may decrease » may increase (Expand search), can decrease (Expand search), to decrease (Expand search)
decrease not » decrease of (Expand search), decrease akt (Expand search), decrease at (Expand search)
not decrease » to decrease (Expand search), not increase (Expand search), and decrease (Expand search)

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: (( decrease any decrease may decrease ) OR ( decrease NOT decrease treg affected ))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "(( decrease any decrease may decrease ) OR ( decrease not decrease treg affected ))~".
• Adding a wildcard symbol may retrieve word variants: (( decrease any decrease may decrease ) OR ( decrease not decrease treg affected ))*.