Though experts put the majority of the blame for homelessness on high housing costs, that’s not to say addiction and mental illness play no part. About one-third of people surveyed by UCSF researchers reported using drugs three or more times a week – mostly methamphetamines. And two-thirds reported experiencing mental health symptoms – including depression, anxiety or hallucinations – in the past 30 days.

In San Francisco, the proportion of unhoused people who reported using drugs and alcohol increased from 42% in 2019 to 52% in 2022. 

But experts caution against putting too much blame on mental illness or addiction when it comes to causing someone’s homelessness. They say many unhoused people start using drugs after they become homeless, either to cope with the grim realities of life on the street, or to help them stay awake at night so they won’t be attacked or robbed while they sleep. 

And they argue that plenty of low-income residents in other states struggle with drug addiction and debilitating psychological conditions. They simply manage to remain off the streets because the rent is cheaper.

Still, a 2019 Los Angeles Times investigation found two-thirds of L.A. County’s residents living on the streets suffer from a psychological or substance abuse disorder or both, far more than what’s been reported in official statistics.

Methamphetamine use is up across the West Coast, and is often to blame for some of the most visible episodes of homelessness seen on California streets. Unfortunately, physicians say meth addiction is confoundingly difficult to treat. While methadone is available to wean heroin addicts off of opioids, no such replacement medication exists for meth.

Worse still, meth can exacerbate existing mental illnesses. Addiction and psychological conditions are often inextricably intertwined, and present a complex case for outreach workers or (more often) law enforcement to confront. A disconcerting number of California board-and-care facilities, which have traditionally housed low-income patients with schizophrenia and other severe conditions, have shuttered in recent years.

As a result, many people in need of acute mental health care instead languish on the street. Sometimes they are too sick to know they need help. To combat that crisis, there has been a recent political push to force people into treatment. Newsom recently launched CARE Court, a program through which California courts can order people with schizophrenia and other serious mental illnesses to follow a treatment plan. He also signed into law a bill that makes it easier to get some people – including those with substance use disorders – into a conservatorship. 

Civil libertarians and disability rights groups argue that conservatorship —when a court-appointed official manages another person’s life, including medical decisions — should be used as sparingly as possible, as it risks violating civil liberties and is a hollow remedy given the severe shortage of actual treatment options.