Can intracranial hypertension be caused in non-obese people. and if yes, then what are the causes?

Yes, many causes: Intracranial hypertension (IH) can be acute or chronic. Acute causes include trauma, bleeding or infection. Chronic causes include tumors, blood vessel problems, imbalance in cerebral spinal fluid secretion/absorption, and hormonal imbalances. After testing to rule out treatable reasons, medications that you are taking are prescribed. Surgery is reserved for refractory cases.

Intracranial HTN: Primary Aldosteronism is one reported cause. So if you have high blood pressure ask your team to test for this. Need 24 hr urine for Na K and creatinine and plasma renin activity and plasm aldosterone test.