Answer by taking a quote from the following article:

Jerome John Garcia (August 1, 1942 - August 9, 1995) was an American singer-songwriter and guitarist, best known for his work as the lead guitarist and as a vocalist with the band Grateful Dead, which came to prominence during the counterculture era in the 1960s. Although he disavowed the role, Garcia was viewed by many as the leader or "spokesman" of the group. One of its founders, Garcia performed with the Grateful Dead for their entire thirty-year career (1965-1995). Garcia also founded and participated in a variety of side projects, including the Saunders-Garcia Band (with longtime friend Merl Saunders), the Jerry Garcia Band, Old and in the Way, the Garcia/Grisman acoustic duo, Legion of Mary, and the New Riders of the Purple Sage (which Garcia co-founded with John Dawson and David Nelson).

On August 9, 1995, at 4:23 am, eight days after his 53rd birthday, Garcia was found dead in his room at the rehabilitation clinic. The cause of death was a heart attack. Garcia had long struggled with drug addiction, weight problems, sleep apnea, heavy smoking, and diabetes--all of which contributed to his physical decline. Lesh remarked that upon hearing of Garcia's death, "I was struck numb; I had lost my oldest surviving friend, my brother." Garcia's funeral was held on August 12, at St. Stephen's Episcopal Church in Belvedere. It was attended by his family, the remaining Grateful Dead members, and their friends, including former basketball player Bill Walton and musician Bob Dylan. Deborah Koons barred Garcia's former wives from the ceremony.  On August 13, approximately 25,000 people attended a municipally sanctioned public memorial at the Polo Fields of San Francisco's Golden Gate Park. Crowds produced hundreds of flowers, gifts, images, and a bagpipe rendition of "Amazing Grace" in remembrance. In the Haight, a single white rose was reportedly tied to a tree near the Dead's former Ashbury house, where a group of followers gathered to mourn.  On the morning of April 4, 1996, after a total lunar eclipse earlier that day, Weir and Deborah Koons, accompanied by Sanjay Mishra, spread half of Garcia's ashes into the Ganges River at the holy city of Rishikesh, India, a site sacred to Hindus. The remaining ashes were poured into the San Francisco Bay. Koons did not allow former wife Carolyn Garcia to attend the spreading of the ashes.

What else troubled him
heavy smoking, and diabetes--all of which contributed to his physical decline.