Reddit reviews The Unquiet Dead: A Psychologist Treats Spirit Possession

Absurd to state there is no single documented case, there is plenty of documentation which describe this phenomenon.

Supernatural entities? Psychosis?

As an atheist, supernatural doesn't fit my world view, however, make of this what you will, it shows there is plenty of similar documented "cases"

• Spirit Possession and Exorcism: History, Psychology, and Neurobiology, Volume 1 - Mental States and the Phenomenon of Possession Patrick McNamara, PhD, Associate Professor of neurology at Boston University School of Medicine, Boston, MA. 2011.
  
  
• Glimpses of the Devil: A Psychiatrist's Personal Accounts of Possession
  
  
• The Growing Evidence for ‘‘Demonic Possession’’: What Should Psychiatry’s Response be? Journal of Religion and Health, Vol. 44, No. 1, Spring 2005, Stafford Betty.
  
  
• The Unquiet Dead: A Psychologist Treats Spirit Possession
  
  
• Possession Demoniacal & Other; T. K. Oesterreich, Professor, University of Tubingen, 1930
  
  
• Dissociative Symptoms and Reported Trauma Among Patients with Spirit Possession and Matched Healthy Controls in Uganda
  

I found this book many years ago. It provided many answers to questions I had regarding spirits that attached and attract to people. It's a good read and informative, writen by a psychologist.
http://www.amazon.com/The-Unquiet-Dead-Psychologist-Possession/dp/0345460871

https://jchristoff.com/alcohol-and-spiritual-possession/

The Unquiet Dead: A Psychologist Treats Spirit Possession https://www.amazon.co.uk/dp/0345460871/ref=cm_sw_r_cp_apa_i_svpyDbYTVRAX7