One study found that significantly fewer boys with SzPD had alcohol problems than a control group of non-schizoids. Another study evaluating personality disorder profiles in substance abusers found that substance abusers who showed schizoid symptoms were more likely to abuse one substance rather than many, in contrast to other personality disorders such as borderline, antisocial or histrionic, which were more likely to abuse many.American psychotherapist Sharon Ekleberry states that the impoverished social connections experienced by people with SzPD limit their exposure to the drug culture and that they have limited inclination to learn how to do illegal drugs. Describing them as "highly resistant to influence", she additionally states that even if they could access illegal drugs, they would be disinclined to use them in public or social settings, and because they would be more likely to use alcohol or cannabis alone than for social disinhibition, they would not be particularly vulnerable to negative consequences in early use. Suicide
Suicide may be a running theme for schizoid individuals, in part due to the knowledge of the large-scale ostracism that would result if their idiosyncratic views were revealed and their experience that most, if not all people, are unrelatable or have polar opposite reactions to them on societally sensitive issues, though they are not likely to actually attempt it. They might be down and depressed when all possible connections have been cut off, but as long as there is some relationship or even hope for one the risk will be low.
For Kretschmer, the majority of schizoids are not either oversensitive or cold, but they are oversensitive and cold "at the same time" in quite different relative proportions, with a tendency to move along these dimensions from one behavior to the other.The second path, that of dynamic psychiatry, began in 1924 with observations by Eugen Bleuler, who observed that the schizoid person and schizoid pathology were not things to be set apart.: p. 5  Ronald Fairbairns seminal work on the schizoid personality, from which most of what is known today about schizoid phenomena is derived, was presented in 1940. Here, Fairbairn delineated four central schizoid themes: 

The need to regulate interpersonal distance as a central focus of concern. The ability to mobilize self-preservative defenses and self-reliance. A pervasive tension between the anxiety-laden need for attachment and the defensive need for distance that manifests in observable behavior as indifference. An overvaluation of the inner world at the expense of the outer world.: p. 9 Following Fairbairn, the dynamic psychiatry tradition has continued to produce rich explorations on the schizoid character, most notably from writers Nannarello (1953), Laing (1965), Winnicott (1965), Guntrip (1969), Khan (1974), Akhtar (1987), Seinfeld (1991), Manfield (1992) and Klein (1995). See also
Asociality
Counterphobic attitude
Dissociation (psychology)
Hermit
Recluse
Schizothymia
Schizotypy
Sluggish cognitive tempo

References
External links

The biological foundations of the schizoid process
NY Times article "Like a Fish Needs a Bicycle: For Some People, Intimacy Is Toxic"
Psychology Today (2017): The Disappearance of the Schizoid Personality