Hoarding of possessions has been associated with a variety of Axis I and Axis II disorders. Frequencies of major depressive disorder, generalized anxiety disorder, social phobia, obsessive compulsive disorder and attention deficit/hyperactivity disorder[19,20,21,22]
are high in people with hoarding disorder. In addition, numerous studies have found Axis II disorders to be prevalent in hoarding. Samuels et al.,
found that 68% of subjects with hoarding symptoms had a personality disorder, compared with only 29% of a non-hoarding group of OCD patients.
In particular, paranoid, schizotypal, avoidant, and obsessive-compulsive personality disorders appear most frequently found among people who hoard.
No studies have examined the frequency of mental disorder in animal hoarding cases although clinical experience indicates that Axis II traits are common. However, some have speculated that animal hoarding may be connected to personality, dissociative, and attachment disorders, and perhaps delusional disorder.[10,13]
Hoarding disorder is not diagnosed if the hoarding behavior can be attributed to other mental or medical conditions. For instance, hoarding behavior is sometimes seen as secondary to schizophrenia, dementia, OCD, or certain forms of mental retardation.
In these cases, hoarding disorder would not be diagnosed.
Little information about animal hoarding secondary to mental or medical disorders is available. The overlap between squalor and both animal hoarding and severe mental illness (e.g., dementia), suggests that it is at least plausible that some cases of animal hoarding may be due to severe mental illnesses. However, Steketee et al.
failed to find differences in self-reported mental health symptoms between people who hoard animals and multiple pet owners, although the animal hoarding participants did report poorer overall functioning in adulthood. Nathanson
stated that a high percentage of the people who hoard animals with whom she has worked appear competent on psychiatric screening. In court proceedings, only one quarter of people hoarding animals are ordered to get pretrial psychiatric evaluations.[6,25]
Although no information about the outcome of the evaluations is provided, Patronek
reported that 26% of the animal hoarding cases in his sample were placed under guardianship, institutional care, or supervised living following legal proceedings
, suggesting serious mental or physical difficulties. These findings suggest the possibility that a minority of animal hoarding cases may be due to other mental disorders. In reviewing potential models for animal hoarding, the Hoarding of Animals Research Consortium (HARC)
suggested that it could be a highly specific form of delusional disorder since it is often accompanied by claims that animals are well-cared for in the face of clear evidence to the contrary and frequent paranoia about animal protection officials.
Researchers have hypothesized that among people who hoard animals, dissociation may be related to their lack of insight and apparent indifference to squalor, and animal suffering.
A 1997 study that examined levels of pet attachment and dissociation among 305 undergraduate students found a significant correlation between pet attachment and dissociation (r = .24). Participants with levels of pet attachment one standard deviation or greater above the mean were three times more likely to exhibit clinical levels of dissociation than were participants with lower levels of pet attachment.
The author's replicated their findings in a later study of 113 veterinary technician students. Results revealed a significant correlation between pet attachment and dissociation (r=.37). Furthermore, 43% of participants with high levels of pet attachment presented with clinical levels of dissociation compared to zero percent of the participants who had levels of pet attachment one standard deviation or more below the mean.
Since people who hoard animals tend to display high levels of emotional attachment to their animals,[8,24]
these findings have potentially important implications for understanding the mechanisms of animal hoarding, and suggest that dissociation may be an important feature in relation to insight and attachment in animal hoarding. Further research is needed to fully understand this relationship.
Patronek et al.
suggested that certain types of animal hoarding (those described as “overwhelmed caregivers”) may be precipitated by factors such as medical illness, loss of financial resources, grief, and mood and/or psychotic disorders. These cases show the excessive attachment characteristic of other animal hoarding cases but are able to maintain a reasonably healthy environment and limited animal population until something happens to change their available resources or ability to cope. They also show less intense reactions to giving up their animals. In such cases, the hoarding behavior appears to be secondary to another disorder or condition. There is no information on the frequency of this form of animal hoarding, however. Another form of animal hoarding (“exploiter” hoarders) may result from antisocial or borderline personality disorders. These individuals appear to lack empathy for their animals, and although they may be articulate and good at self-presentation, they are manipulative, reject the legitimacy of animal care authorities, and experience little guilt or remorse over the condition of their animals. Even so, very few hoarding cases fit what is described as the “exploiter” category.