A longitudinal study has shown that personality disorder predicts the occurrence of later depression and anxiety, as well as the absence of long-term relationships — effects that are not accounted for by pre-existing social, mental health or substance problems. The findings provide strong support for including personality disorder in global studies of the burden of mental disorders in order to improve the understanding of mental health in the population.
Previous research has established that personality disorders are common mental disorders linked to a broad range of problems, including poor general health, long-term unemployment, reduced life expectancies and alcohol and substance abuse. In spite of these findings, policy-informing initiatives such as the Global Burden of Disease have not included personality disorders within their scope. The broad range of coexisting social and health problems in people with personality disorder make it hard to assess whether there are independent social and health effects of personality disorder, and may be the reason why personality disorders are excluded in global assessments of disease burden. Likewise, studies on long-term effects of personality disorders are rare and focus mainly on populations seeking treatment and on a selection of subtypes of personality disorder.
In order to get a more complete understanding of the disease burden related to personality disorders, researchers examined the long-term effects of personality disorders on social functioning and mental health. They used data from a large population-based, cohort study of a random sample of 1635 non-treatment-seeking young adults from Victoria, Australia, between 1992, and 2014. Presence and severity of personality disorder were evaluated with an interview (the Standardized Assessment of Personality) when participants were age 24 years (Wave 8). When participants were 35 years of age (Wave 10), they were assessed on the occurrence of the following outcomes: anxiety disorder, major depressive disorder, smoking and consumption of alcohol, use of illicit substances, not in paid employment at the present time, ever been divorced or having separated from a long-term partner, not in a relationship at the present time, and receiving government welfare.
The findings, published in the journal the Lancet Psychiatry revealed that 27% of individuals in the study had either personality disorder or personality difficulties at age 24 years. The presence of personality disorder in young adulthood (at age 24 years) was linked to significantly poorer mental health and social functioning 10 years after (at age 35 years). These associations were not explained by the occurrence of previous social or mental health problems or prior patterns of substance abuse.
At age 35 years, severity of personality disorder was independently associated with not being in a relationship, increased odds of an anxiety disorder, and major depression.
The researchers found that at 24 years old, participants who had personality disorders or difficulties already differed significantly from those without personality disorders or difficulties in terms of social functioning and health problems. The severity of personality disorder at this age was linked to receipt of welfare, cigarette smoking, the presence of common mental disorders, and the absence of post-secondary education. Significantly, participants at this age were already smoking cigarettes more heavily (but their frequency of smoking did not seem to increase over time) compared with those without personality disorder or difficulty.
After 10 years, at age 35 years, individuals who had personality disorders or difficulties had poorer outcomes in mental health and relationships, even after controlling for their baseline level of disadvantage in their mid-20s. Participants with simple or complex personality disorders were significantly more likely to not be in a relationship at 35 years, compared to those without personality disorders. The researchers state that long-term relationships might not even have formed during the period of follow-up (from age 25 to 35 years). Participants with personality disorder and difficultiesalso had a greater risk of developing depression and anxiety by age 35 years, even when researchers controlled for the presence of mental disorder at age 24 years. They further suggest that the presence of personality difficulties is an independent risk factor for future depression and anxiety. Additionally, the study showed no significant association between severity of personality disorder and smoking status at age 35.
The overall findings of this study suggest that personality disorder is associated with negative social functioning, and increased occurrence of substance abuse and mental health problems earlier in adulthood. Later in life, even after taking these differences into account, individuals with personality disorder and personality difficulties are likely to have mental health effects and relational function that is significantly poorer than those without personality disorder.
Personality disorder is currently not incorporated into national or global assessments of disease burden. The findings of this study suggest that future efforts to improve the understanding of mental health in the population could be more successful if the effects of personality disorder are taken into account in the assessment of disease burden. The findings also have implications for prevention and early intervention, suggesting the need for new strategies to address the significant social and disease burdens suffered by individuals with personality disorder. Additional investment will be required to deal with the significant social and disease burdens experienced by individuals with personality disorder.
Written By: Nigar Celep, BASc