I used cocaine for roughly 4 years. i quit 15 years ago. am i in any danger of dimentia or anything else that happens later in life because of the 4 years of use?

Congratulations on quitting and staying out of it . It can have effect on blood pressure; have yourself checked regularly by your primary care and don’t go back to taking it .

At this point, you will no longer be at risk for any cocaine-induced problems. Dementia will not be a result of your prior usage. Most severe effects on brain and/or heart occur at the time of abuse, and typically would not be an ongoing risk subsequent to discontinuation after a few weeks.

During those 4 years of cocaine use, did you experience cognitive problems, ie impairment in attention, working memory, episodic memory, or executive functioning? Do you have any such problems currently? If these are issues of concern, perhaps a reason why you asked, an evaluation with a Neuropsychiatrist or a similar professional is reasonable to consider.