Hello dear
Warm  welcome to Healthcaremagic.com
I have evaluated your query  for  your  brother  in details  .
*  This is the depressive  disorder  following  withdrawl  of  
smoking weed 
    as  the  central  nervous  system  stimulant  action  has  gone  due to
    stoppage of the weed .
*  Guidelines for better  outcome  
-  Allow him plenty of liquids to maintain hydration .
-  Deep breathing  exercises , walking in fresh air , 
YOGA  are  corner  stone
    of  the  treatment .
-  Suggestion therapy , behavior therapy , concentration techniques  also
    help  great .
-  Make him devoid of 
stress , 
anxiety by positive  attitude  training .
-  See that he takes  regular  sound sleep of 8 hours .
-  Make him more involved  in  his likelihood  activities .
Wishing  him  fine recovery .
Feel free to ask any further  queries .
Regards  .