Treatment Compliance in Patients With Co-Occurring Mental Illness and Substance Abuse

Some psychiatric comorbidity factors that can affect SUD treatment include the type of psychiatric disorder, severity of the comorbid psychiatric condition, early onset of illness and level of cognitive impairment (Broome et al., 1999; Rowe et al., 2004). The clinical features of some types of psychiatric disorders may become risk factors for poor treatment compliance. For example, among patients with schizophrenia, the lack of awareness of the illness, paranoid ideation, persecutory delusions and lack of initiative can worsen treatment compliance (Owen et al., 1996).

One of the psychiatric aspects that can greatly affect SUD treatment compliance is the patient's level of neurocognitive functioning (Aharonovich et al., 2003; Fals-Stewart and Schafer, 1992a). Attention, mental reasoning and spatial processing are some of the cognitive domains that are significantly affected among noncompliant patients (Aharonovich et al., 2003).

More severe comorbidity has been associated with poorer therapeutic alliance, and treatment alliance can predict patient retention (Barber et al., 2000). Patients with moderate and severe psychiatric problems are not likely to remain in treatment unless they develop a strong therapeutic relationship with their therapist (Petry et al., 2001).

Studies have documented that treatment compliance can be affected by the concurrent presence of substance abuse (Keck et al., 1997; Lambert et al., 2005; Olfson et al., 2000). In patients with schizophrenia, medication noncompliance has been significantly associated with substance abuse, this in turn with a greater symptom severity than other groups (Olfson et al., 2000; Owen et al., 1996).

For patients with bipolar disorder (BD), noncompliance was significantly associated with the presence of a comorbid SUD, and the most common reported reason was denial of need for treatment. In a study by Weiss et al. (1998), compliance was significantly associated with treatment with divalproex (Depakote), compared to treatment with combined lithium(Drug information on lithium) (Eskalith, Lithobid). The study also showed that patients with BD and SUD who were prescribed benzodiazepines, neuroleptics and tricyclic antidepressants tended to take more medication than prescribed.

With regard to comorbid personality disorders and SUDs, results are not conclusive. However, borderline and antisocial personality disorders predict lower treatment retention rates (Marlowe et al., 1997). In addition, the concurrent presence of Axis II disorders on top of the Axis I disorders and SUD seems to worsen treatment compliance even more. A study showed that inpatients with triple comorbidity (Axis I and Axis II disorders plus SUD) were less likely to be compliant with the treatment plan than those without triple comorbidity (Ross et al., 2003).

Adolescents with comorbid mental illness and substance abuse are a unique clinical population because of the high risk that the problems will continue or worsen during adulthood. A retrospective record review of one year of admissions to a residential adolescent substance abuse treatment program showed that patients with attention-deficit/hyperactivity disorder and those with conduct disorder had the lowest treatment compliance (Wise et al., 2001).

In another study, investigators showed that adolescents with SUD who have comorbid affective and adjustment disorders have better compliance, whereas patients with conduct disorders have poorer compliance. Furthermore, patients who received psychotropic medications have better treatment compliance (Kaminer et al., 1992).