Schizoid personality disorder (SPD) is a personality disorder characterised by a detachment from social interactions and a tendency towards a solitary lifestyle. Specifically, SPD is characterised by at least three of the following:

  • Emotional coldness, detachment or reduced affectivity.
  • Limited capacity to express either positive or negative emotions towards others.
  • Consistent preference for solitary activities.
  • Very few (if any) close friends or relationships, and a lack of desire for such.
  • Indifference to either praise or criticism.
  • Taking pleasure in few, if any, activities.
  • Indifference to social norms and conventions.
  • Preoccupation with fantasy and introspection.
  • Lack of desire for sexual experiences with another person.

This description is provided by the ICD-10 (International Classification of Diseases).

SPD is relatively rare compared with other personality disorders, being estimated at less than 1% of the general population. It is believed by some to correlate with the INTJ and INTP personality types in the Myers-Briggs type indicator. SPD is far more common amongst males than females, although this could be due in part to the fact that schizoid symptoms are far less socially acceptable in women.

SPD shares several aspects with depression, avoidant personality disorder and Asperger's Syndrome, and can be difficult to distinguish from these other disorders. However, there are some important differentiating features:

  • Unlike depression, SPD does not involve feelings of helplessness, worthlessness or sadness. People with SPD do not generally consider themselves inferior to others, although they will probably recognise that they are different.
  • Unlike avoidant personality disorder, those affected with SPD do not avoid social interactions due to anxiety or feelings of incompetence, but because they are genuinely indifferent to social relationships.
  • Unlike Asperger's syndrome, SPD does not involve physical symptoms such as hand-flapping or lack of eye-contact, and sufferers of SPD are not awkward in social situations (although they may well be bored). SPD does not affect the ability to express oneself or communicate effectively with others, and is not believed to be related to any form of autism.

It is disputed whether SPD should be considered a "disorder" at all, since it does not necessarily involve any suffering either for the affected individual or those around him. Many people are critical of society's tendency to pathologise certain personality traits simply because they are not compatible with the status quo. However in some cases, strong SPD symptoms may result in an affected person living a dull and unfulfilling life.

There is also disagreement about the relationship between SPD and schizophrenia. Some argue that the two conditions are entirely unrelated except by the origin of the word (meaing "split", in the case of SPD it is the individual that is "split" from society, rather than the actual mind being damaged), while others maintain that SPD exhibits a subset of the symptoms of schizophrenia and may, in rare cases, be an indicator of the onset of the more serious disease.