I understand your concern. However more clarity is needed regarding his problem to decide on the severity of his condition. Ganja / cannabis affects the nervous system which has the ability to cause all sorts of problems including depression, anxiety, psychosis, amotivation or even dementia. However it is easily manageable with appropriate treatment. Some counselling sessions along with medical help might be useful for him. I suggest you take him for a detailed psychiatric evaluation. I would also be more than happy to help you with that if you are looking for further online assistance. Discussions will be held confidential. You can directly consult with me through Practo as needed. Online chat consultation is also available.

There is a possibility that your brother is facing psychological disorder I suggest you to consult a psychiatrist for diagnostic evaluation and management.