Schizoid Personality Disorder (SPD) is described as a chronic pattern of the following characteristics as listed in The World Health Organization's (WHO) International Classification of Diseases (ICD-10):
- Emotional coldness, detachment or reduced affect.
- Limited capacity to express either positive or negative emotions towards others.
- Consistent preference for solitary activities.
- Very few, if any, close friends or personal relationship, and a lack of desire for such.
- Indifference to either praise or criticism.
- Little interest in having sexual experiences with another person (taking age into account).
- Taking pleasure in few, if any, activities.
- Indifference to social norms and conventions.
- Preoccupation with fantasy and introspection.
Effecting less then 1% of the population, it varies considerably from Schizophrenia. Here are a couple of resources that someone found very helpful to them:
https://www.youtube.com/watch?v=gjOl7sfeJJk
https://www.youtube.com/watch?v=BMqcHOqQsLo&t=431s
For further reading on SPD, please go here: https://en.wikipedia.org/wiki