Prevalence and Determinants of Everyday Disability in Schizophrenia

Philip D. Harvey, PhD
Professor of Psychiatry
University of Miami Miller School of Medicine
Miami, FL

Philip D. Harvey is a Professor of Psychiatry and Behavioral Sciences at the University of Miami Miller School of Medicine. An internationally recognized expert in cognitive impairment and functional disability associated with severe mental illnesses, his research primarily focuses on schizophrenia, mood disorders, and neuropsychiatric aspects of aging. Dr. Harvey’s extensive publications have significantly advanced the understanding of cognitive deficits and their impact on daily functioning.

This video discusses the multifaceted nature of disability in schizophrenia, highlighting the impact of cognitive impairments, functional capacity, and negative symptoms on everyday outcomes like independent living and social engagement. He explains that while cognition affects vocational and independent living outcomes, social outcomes are also linked to social motivation and competence. He underscores that targeting multiple factors will be crucial to effectively reduce disability in severe mental illness.

This presentation is part of the Emerging Approaches in Schizophrenia Editorial Focus collection from Psychiatrist.com News. The collection focuses on the latest advances in schizophrenia treatment, with an emphasis on emerging therapies that go beyond traditional dopaminergic approaches.

To learn more and watch more videos, visit our Emerging Approaches in Schizophrenia collection.

Transcript

[00:08 – 01:04] Introduction to Everyday Disability in Schizophrenia and Bipolar Disorder

Hi, I’m Phil Harvey from the University of Miami Miller School of Medicine. I’m going to talk a little bit about the prevalence and determinants of everyday disability in schizophrenia. One of the most striking things about schizophrenia is how disabling it is.

As you see on this graphic, fewer than 30% of people with schizophrenia commonly manage to achieve milestones that the general population seems to achieve all the time, such as being able to live independently, have a relationship that’s equivalent to marriage, or be employed full-time. But we see here also that bipolar disorder is marked by considerable disability as well. And interestingly enough, there’s been a lot less research on disability in bipolar disorder until the early 2000s because people actually thought that bipolar disorder was not a disabling condition.

[01:05 – 02:23] Measuring Functional Disability: Methods and Observations

So how do you assess functional disability? You can have people do performance-based tests that measure critical abilities, like using a driving simulator or having someone do digital banking tasks. You can ask them how they do. You can have someone who knows them report on them.

You could use direct observation. Passive and active digital phenotyping are great strategies for direct observation that don’t require being with the person the whole time. And you can also use objective information.

If someone tells you that they have a job, you can see how much they work by looking at their tax information. So it’s easy to determine objectively if people have met functional milestones. So what determines everyday outcomes? The usual suspects include social and neurocognition, basically other symptoms like functional capacity, such as social skills and the ability to perform everyday functional actions in analog situations, negative symptoms, including reduced emotional experience and reduced emotional expression, mood states, such as depression, and other contributors, such as defeatist beliefs or impairments in self-assessment, which are actually more important than people thought at first.

[02:24 – 03:29] Functional Capacity and Its Relationship to Real-World Outcomes

So the concept of functional capacity, it’s the ability to perform functionally skilled acts, such as social competence, vocational skills, and everyday activities. There’s considerable evidence that suggests that functional capacity may be more proximal to real-world function than cognition, and studies have shown that it consistently mediates the impact of cognitive impairment. What this means is that if you’ve got cognitive impairment, it makes you more challenged in the ability to perform the skills you need to perform to function in the real world, and that’s where the impact comes from.

So the UCSD Performance-Based Skills Assessment has been a widely used functional capacity measure. It measures five different domains, comprehension and planning, financial management, communication, mobility, and household chores. Basically, it involves things like being able to use the telephone, manage money, write a check, figure out a bus schedule, as well as engage in things like doing actual shopping tasks, and it’s scaled to a 100-point score.

[03:30 – 04:47] UPSA: Assessing Independent Living Skills and Predicting Disability

So one of the things that’s really important is that the UPSA and its shorter version, the UPSA-B, is highly correlated with the actual ability to live independently. So you see here there’s three different outcomes, head of the household, community resident, and supervised living, and this is a combined study of people with schizophrenia and people with bipolar disorder. And as you see, the people who are living independently have clearly the highest scores on the UPSA, and people who are living in supported living clearly have the lowest.

But if you look at the small print next to residential status, you’ll see that diagnosis, bipolar versus schizophrenia, contributes no version to the predictive, variance to the predictive equation. Poorer performance on the UPSA is associated with residential challenges in both schizophrenia and bipolar disorder, with no additional contribution of diagnostic status on top of that. And if you look at a further analysis of that same data set, what we see is that the ability to perform the UPSA, referred to in this slide as adaptive capacity, is the single strongest predictor of the ability to perform everyday activities, including independent living.

[04:48 – 05:51] Cognitive Impairments in Schizophrenia and Their Impact on Functioning

There are other contributors, but you see that the direct contribution of neurocognition is small compared to functional capacity, and that applies in both bipolar disorder and in schizophrenia. Since people with schizophrenia don’t have manic episodes, there’s a slightly bigger contribution of manic symptoms to disability and bipolar disorder, but mood symptoms are important in both, and negative symptoms are critical as well. So there’s several important domains of cognitive dysfunction in schizophrenia.

Attention and vigilance, processing speed, working memory, executive functioning, and episodic memory. They all tend to aggregate together to generate composite cognitive ability scores, which are then used for estimation of functional potential and used in research studies. Bipolar disorder and major depression essentially have very similar profiles, and the same cognitive outcomes assessment, the matrix consensus cognitive battery, works just as well in bipolar disorder and in major depression.

[05:52 – 07:00] Correlations Between Cognitive Performance and Functional Outcomes

You don’t need to assess cognition differently across neuropsychiatric conditions. The same assessment battery captures the same critical factors. So in meta-analyses, the people have looked at the correlation of neuropsychological performance, social cognition, and disability.

In schizophrenia, there have been two fairly large-scale meta-analyses. The most recent one had close to 13,000 participants in it, and in a meta-analysis of bipolar disorder done in 2012, there were 1,344 patients with bipolar disorder, and the next slide shows that the meta-analytic correlation between cognitive functioning and disability in schizophrenia and bipolar disorder is essentially indistinguishable, suggesting that cognitive performance mediated by functional capacity is a very potent driver of disability. Many studies don’t measure functional capacity, they just measure cognition, so it’s easier to get a large sample in a meta-analysis if you look at cognition, but you have to hold the thought that the impact of cognition is by impairing functional skills.

[07:01 – 08:24] Social Outcomes vs. Vocational and Residential Outcomes

Disability is not just one thing. One of the things that’s important to keep in mind is that achievement of functional milestones varies across the milestones. In samples of people with schizophrenia, correlations between milestone achievements are very small.

In this sample, 81% had worked some time, only 12% now, 54% had a marriage-like relationship, and 44% were living independently, but these milestones didn’t converge with each other, so there’s remarkably small correlations even between working and living independently. So what we see here is you cannot calculate a total score for disability because it’s not just one thing, and there are probably different determinants of different aspects of disability. So there’s differences in the determinations of outcomes.

Basically, social cognition and social competence are correlated with social outcomes, but not as much with work or independence. Similarly, negative symptoms seem to be a very potent predictor of bad social outcomes, more so than social cognition or social competence. And you can see in this slide here that social amotivation is much more important than your social competence or your social cognitive ability in predicting independent ratings of your current social functioning.

[08:25 – 10:32] Multidimensional Disability and Pathways for Targeted Interventions

Predictive models have shown very similar things. In this study that we did on the left with 821 participants, we saw that negative symptoms were correlated significantly with social outcomes, but not at all with vocational or residential outcomes, and that cognition and functional capacity measured with the UPSA were correlated with both vocational and everyday living outcomes, but not with social outcomes. Confirming this sort of separation, and in this very large study done in Italy, the same thing is demonstrated.

There’s a mediated impact of cognition through functional capacity on multidimensional assessments of everyday functioning, measured with the SLAW, the specific levels of functioning, but negative symptoms are associated with social outcomes in that study as well, and the impact of cognition was mediated by its impact on functional capacity. So for everyday living and for vocational outcomes, cognition impacts on skills, skills deficit impacts on functioning. For social outcomes, social motivation and your social competence impact on how you do, but negative symptoms and lack of interest in socializing seems to be a more important predictor.

So disability is multidimensional in serious mental illness. It’s very similar in topography across schizophrenia and bipolar disorder. The determinants of different elements of disability seem different.

Basically what we see is that disability looks the same, and it has the same causes which are different from each other across these different conditions. It seems really unlikely that a single treatment would be able to reduce all elements of disability unless it can simultaneously target cognition, functional capacity, and negative symptoms. There are some treatments in development that have shown benefits on both cognition and negative symptoms as well as psychotic symptoms, and I think that may be the path forward to reducing disability with pharmacological treatment.