Medication management ability is a vital aspect of staying adherent to medication regimens. As hypothesized, we found significantly worse performance on a performance-based measure of medication management ability in bipolar disorder relative to NCs. Participants with bipolar disorder made three times as many errors as the NCs group, and errors on the MMAA were seen in taking too few pills rather than too many. Despite relatively better cognitive and symptom profiles than patients with schizophrenia, performance on the MMAA between the two groups did not differ. Among patients with bipolar disorder, the most potent predictor of MMAA scores was, as hypothesized, cognitive impairment. However, there were no other significant associations. The Memory subscale of the DRS significantly predicted MMAA scores, but Initiation/Perseveration and Attention did not. Future study will be needed to understand how specific cognitive abilities in bipolar disorder map on to medication management. Our data suggests that interventions to enhance medication adherence in later-life bipolar disorder may benefit from including compensatory strategies (e.g., medication reminders and calendars) to counteract memory deficits.
There are a number of study limitations. The small sample size may have lacked power to detect certain associations (e.g., age). The sample was also comprised of stably treated bipolar I outpatients with mild levels of psychiatric symptoms. Research with more severely ill patients would be needed to gauge the effect of symptoms of medication management ability, and these results may not apply to other sub-groups of patients with bipolar disorder, including bipolar disorder II or bipolar disorder NOS. We lacked a measure of manic symptoms in this sample, such as the Young Mania Rating Scale(20
), and cannot rule out that manic symptoms impaired performance. However, none of the bipolar participants were inpatients and their PANSS excitement scores were not elevated beyond that found in the schizophrenia group as would be expected among people in manic states. We lacked a measure of medication adherence in this sample, and therefore we cannot be certain that MMAA performance correlates with real-world adherence to psychotropic or non-psychotropic medications among people with bipolar disorder. However, the MMAA has been previously associated with actual antipsychotic adherence as measured by pharmacy record in a sample with schizophrenia(11
Despite these limitations, our findings suggest several potentially important aspects of medication management in later-life bipolar disorder. There were a large number of errors by patients with bipolar disorder. Despite their relatively better cognitive and psychiatric symptom severity profiles in this study compared to patients with schizophrenia, patients with bipolar disorder showed a similar pattern of performance on the MMAA. The most common type of error among bipolar patients (along with patients with schizophrenia) was in taking too few medications. This study suggests that, despite somewhat better clinical state among older patients with bipolar disorder, impairments in medication management ability is similar between later life bipolar disorder and schizophrenia. This corresponds with previous study by Bartels and colleagues, indicating a similar degree of impairment in community living skills in patients with either bipolar disorder or schizophrenia, despite some differences in symptoms (21
Our findings have potential implications for understanding unintentional non-adherence among older patients with bipolar disorder. In mixed-age patients with bipolar disorder, the rate of non-adherence is around 40 to 50%(22
), but there may be better self-reported and pharmacy record assessed adherence in older age groups (23
). It may be that rates of intentional non-adherence decrease with older age alongside greater insight and acceptance of one’s diagnosis (24
). However, our findings suggest that older adults may be at risk for unintentional non-adherence due to diminished capacity to manage medications. Pharmacy record measures of adherence may not detect these kinds of unintentional medication errors, and patients may not be aware of difficulties in medication management on self-report measures. Future research should examine correspondence between the MMAA and self-report, pharmacy record, and pill count measures of actual adherence among older adults.
As with Jeste et al (13
) in their sample of patients with schizophrenia, we found strong association between the Dementia Rating Scale and MMAA scores. There is mounting evidence that neuropsychological performance is impaired in bipolar disorder(6
), longer duration of illness may relate to worsening deficits (6
), and substantial proportion of older adults with bipolar disorder show signs of cognitive impairment (3
). Contrary to our hypotheses, the pattern of relationships between neurocognitive deficits and MMAA scores appeared general rather than specific. Although the memory subscale had the highest correlation with the MMAA, this relationship was not significantly stronger than that found between any of the other DRS subscale scores.
In addition to our limited sample size, one reason to be cautious in overinterpreting the lack of evidence of differential cognitive effects on medication management is the nature of the DRS itself. The DRS is relatively simple and brief, and can be administered to patients with a wide range of functioning. However, the DRS may be suboptimal as a means of identifying the effects of different cognitive abilities on medication management. For instance, prospective memory, or the ability to “remember to remember”(25
), is a cognitive domain that entails planning and metacognition, which are apart from the initiation/perseveration subscale of the DRS, which taps into disinhibition-related aspects of executive function. Future research with more sensitive neuropsychological instruments should investigate which domains of cognitive functioning map on to the tasks involved in medication management.
It was somewhat surprising that neither HAM-D nor BPRS scores correlated with MMAA performance. Our sample had a relatively mild level of symptoms, but not all were euthymic. It may be that medication management ability is more ‘trait-like’ in bipolar disorder. There were no other significant relationships with the MMAA, although older age approached significance. This may stem from the marked heterogeneity in later life bipolar disorder, as the mean and standard deviation in the number of errors on the MMAA were roughly equivalent.
The primary clinical implication is that, in addition to adherence, medication management ability may be an important area to assess in later life bipolar patients. Given the high degree of medical comorbidity among older patients with bipolar disorder(9
) along with the combination strategies used in treating bipolar illness, most people have a large number medications. Clinicians may need to ask about how patients organize their medications, and what sorts of strategies they use to stay adherent. The MMAA is a relatively brief (15 minute) measure of medication management ability that could be useful in a clinical setting. Psychosocial interventions developed to enhance medication adherence in younger adults with bipolar disorder are largely targeted toward enhancing motivation to take medications(26
). Adaptation of psychosocial intervention in later life bipolar disorder should incorporate training in compensatory strategies to make medication taking more automatic – such as pill boxes, forming implementations intentions, and routinizing medication taking through pairing with daily events. We have previously developed and evaluated such an intervention in a pilot study, described elsewhere(27
). Lastly, research on the optimal treatment and clinical course of later life bipolar disorder is needed, particularly how functional disability can be addressed in this often vulnerable group of patients.