Final answer:
Hoarding disorder is the condition most closely associated with difficulty in discarding possessions leading to cluttered living spaces, as described in the DSM-5.
Step-by-step explanation:
The difficulty in discarding possessions that results in congested and cluttered living spaces is most characteristic of Hoarding disorder. This disorder is referenced in the DSM-5 and is distinct from Obsessive-Compulsive Disorder (OCD), Obsessive-Compulsive Personality Disorder (OCPD), and substance use disorders, including those resulting from amphetamine use. Hoarding disorder involves persistent difficulty discarding or parting with possessions, regardless of their actual value, and is associated with significant distress or impairment in social, occupational, or other important areas of functioning.