To what extent does solitary confinement affect a person's mind?

Solitary confinement has the potential to either develop new mental illnesses or worsen existing conditions for people. Research from the Journal of the American Academy of Psychiatry and the Law has found that "[t]he stress, lack of meaningful social contact, and unstructured days can exacerbate symptoms of [mental] illness or provoke recurrence." More often than not, when someone is in solitary confinement, they are put into a cramped cell with little more than a shoddy bed and sanitary facilities. There's nothing to do besides eat their scheduled meals and stare at the ceiling. This sensory deprivation and loss of purposefulness only leads to the deterioration of people's mental states, rather than allowing prisoners to self-reflect on their wrongdoings. Statistics have shown that those who have been in solitary confinement were more likely to commit both suicide and homicide- an undeniable testament to solitary confinement's inability to improve prisoners' behavioral issues.

It has been scientifically proven that parts of the brain atrophy when in solitary confinement for extended periods of time, literally harming the brain. Robert King, a man who spent 29 years living in solitary confinement, stated that his memory was impaired and he could no longer navigate, both of which signify damage to the hippocampus. To support the idea that the size of the brain changes in solitary confinement, an experiment was conducted on mice revealing that one month of solitary confinement shrank neurons in sensory and motor regions by 20 percent. Something is definitely wrong if a punishment ends up significantly changing the way brains work, especially under the guise of “bettering” a prisoner.

See these articles on atrophy in the brain and solitary confinement for more:

After a prisoner is released from solitary confinement, its effects can still be felt for years afterwards. A New York Times article interviewing researchers and prisoners reveals their experiences after solitary confinement. “[Prisoners] startled easily, avoided crowds, sought out confined spaces and were overwhelmed by sensory stimulation.” Being confined to such a small area for such a long time, it makes sense that those who go are released from solitary confinement try to make their way back to familiar environment. However, this does not mean that this is a good thing or something that will simply pass. People who go through solitary confinement and show signs of anti-social behavior are more than likely going to relapse into harmful actions, which could affect themselves or the people around them. The constant stress of sensory overload that may come from being in environments that are no longer familiar to someone who has been in solitary confinement could also play a big part in reducing the ability to socialize.