The importance of neuropsychology in mental health

Sifting through chronic and severe conditions with understanding, predictions and flexible planning

Often misunderstood or underestimated, so-called ‘dirty’ neuropsychology plays an important role in predicting outcomes and establishing treatment plans for patients with severe mental health conditions such as schizophrenia. We highlight the importance of a paradigm shift to a more biopsychosocial model of patient care, which improves community functioning and has greater alignment with patient goals.

This article reflects on our careers as clinical neuropsychologists entering into relatively uncharted territory. Fourteen years ago, we began our roles together at what was then a major psychiatric hospital in Sydney, with a core population of patients with chronic and severe mental health conditions – in particular schizophrenia but also bipolar, schizoaffective disorder, borderline personality disorder and depression. When we started, we had very little support because no one we knew worked in this area, and mental health in neuropsychology seemed to be uncharted territory in 2007. We were also the first neuropsychologists at that hospital and once the excitement of a new service died down, we needed to develop our role identities and explain how we fit into the hospital processes. It was an incredible learning journey but like all evolving processes, mistakes were made along the way.

Since this time, we wouldn’t say there has been a massive shift of focus in neuropsychology towards major mental health conditions, but there have been steps in the right direction, with a range of leaders in the field advocating for its importance. We think one reason for the lack of interest of neuropsychologists in this area is due to what we in the business would refer to as it being ‘dirty’ neuropsychology. By that we mean, there are no discrete lesions or even a clear pattern of cognitive performance which is the expected pattern for major psychiatric illness.

It gets even messier when you add age-related changes and have to delineate whether their profile fits late onset major psychiatric illness, a neurocognitive disorder or, indeed, both. The main role of a neuropsychologist in mental health is to firstly characterise the degree and pattern of cognitive impairment as well as to provide an indication of how the deficits might impact on functioning. As you will see, cognition and its impact on community function is the future for understanding and predicting outcomes for people with severe mental health conditions.

What is schizophrenia?

Like autism, schizophrenia is also considered a spectrum illness, and ranges from the personality variants (Cluster A personality disorders) to the more chronic forms of schizophrenia and schizoaffective disorder (American Psychiatric Association, 2013).

There are particular time-points where it is more likely the illness will onset. The psychiatry guidelines (Galletly et al., 2016) describe men as having a slightly earlier average age of onset than women, from within mid-adolescence to early adulthood. Women also have a second smaller peak between ages 45–50 (believed to be linked to menopause). Both groups then have later life risk periods between 40–60 (late onset) and after the age of 60 (very late onset). For the adolescent onset, this is particularly important as it occurs at the time that the prefrontal cortex is still developing and life skills are being acquired.

There are many theories about how or why people develop schizophrenia. These include the possibility of a neurochemical imbalance, genetic loading (e.g., Snitz et al., 2006) and environmental factors (e.g., Insel et al., 2010). It has also been hypothesised that schizophrenia is a neurodevelopmental condition. Population-based studies have suggested that there are early markers such as delays in early developmental milestones and lower average IQ (Mollon & Reichenberg, 2018). Models which bring this information together detail problematic brain development from gestation and describe a sequence of events and risk factors associated with the phases of the syndrome (Lencz et al., 2001).

From a neuropsychological perspective, schizophrenia should be best considered in this developmental light, with longstanding issues impacting academics and skill acquisition. This should be the expectation when conducting neuropsychological assessments and intervention. This is in contrast with other clinical populations that neuropsychologists will see such as TBI, stroke and dementia, where the individuals had generally normal development in childhood but sustained brain insult or changes in later life. This is likely to impact significantly on the level of lifetime disability.

Cognition myths

Most neuropsychologists will remember their undergraduate psychopathology unit, or that one lecture in postgraduate studies (yes, we are having a dig at the lack of importance our training has placed on this illness) and understand that schizophrenia is characterised by positive symptoms (hallucinations, delusions and thought disorder) and negative symptoms (such as amotivation, anhedonia, blunted affect and poverty of thought). When people think about schizophrenia, they often think of these symptoms and cognitive deficits do not readily come to mind.

A common misconception people make about schizophrenia is the idea that the primary cause of the cognitive impairment is from the psychotic symptoms. For example, that poor attention is due to distraction from voices, or due to medication. Yes, these can cause some impairment, but they are not the main mechanism. Cognitive impairment due to schizophrenia is actually caused by the disease process and not a secondary effect. Therefore, the best way to think about this is to consider schizophrenia as an illness which causes positive symptoms, negative symptoms and – separately – cognitive impairment. There was a push for cognitive symptoms to be included in the Diagnostic and Statistical Manual of Mental Disorders 5th edition (DSM-5) diagnostic criteria for schizophrenia (Keefe, 2008), but this did not happen.

We know that these symptoms occur via different mechanisms as they have different times of onset in the illness and different trajectories over the disease course (Sommer et al., 2016). Treatment is also different for different symptom classes. Figure 1 (from Sommer et al., 2016) demonstrates the typical courses for the different symptom classes. As you can see, cognitive deficits onset early then plateau but remain present throughout the duration of the illness. Negative symptoms onset later but also remain present throughout the duration of illness. Positive symptoms emerge later, and their presence is dependent upon the treatability of the symptoms via antipsychotic medication. Thus, the positive symptoms fluctuate and are treatable, in some individuals remitting entirely. However, the negative symptoms and cognitive impairment do not, and current medications have not demonstrated meaningful improvement (Kahn, 2020).

Cognitive deficits

Cognitive deficits caused by schizophrenia are present in up to 70–90 per cent of individuals with schizophrenia. As noted, cognitive functioning typically declines early in the illness then plateaus (Lewandowski et al., 2011), with cognitive deficits relatively stable across clinical states. That is, they do not change markedly due to psychotic symptoms and do not improve once the psychotic symptoms remit (Dickinson et al., 2007).

The cognitive profile in schizophrenia is highly variable with domains affected typically including attention and vigilance, working memory, verbal learning, speed of information processing and executive functioning including reasoning, mental flexibility and problem-solving. Most research suggests that, on average, the impairments are 1–2 standard deviations below the mean (e.g., Kern et al., 2011). However, there is significant variability and schizophrenia in general is very much a heterogeneous condition.

There is growing recognition that social cognition deficits are an integral aspect of the cognitive profile of schizophrenia. This can include difficulties with recognition of facial expressions and the emotions of others, as well as higher level mental state reasoning, such as theory of mind.

A paradigm shift is required (and has started) in psychiatry whereby patient management, particularly for more chronic psychotic illnesses, is changing

Neuropsychology’s role

Mental health consumers experience particular disadvantages which are largely due to their illness onsetting in late adolescence and early adulthood. This affects them in acquiring early knowledge and changes the trajectory of their life. According to the People living with psychotic illness 2010 survey (Morgan et al. 2012), people with psychotic illness have lower educational attainment, lower rates of employment, trouble retaining their accommodation and are at greater risk of homelessness. They can experience significant social isolation due to the symptoms of their illness and this isolation can be exacerbated by multiple episodes of illness, periods of hospitalisation, stigma and discrimination that can make maintenance of family and social contacts more difficult and impede their ability to form long-term relationships. Further, older people with schizophrenia not only experience cognitive impairment early in life, with associated functional difficulties throughout their lives, but in later life are greater than two times more likely to develop dementia (Ribe et al., 2015). They are also up to four times more likely to be placed in residential aged care at an earlier age than other people of the same age with no mental illness (Andrews et al., 2009).

While it is well known that the positive symptoms of schizophrenia interfere with functioning, the biggest predictor of community outcomes is actually cognitive functioning (Green, 2006). A Sydney-based longitudinal study (Lee et al., 2013) found that baseline neuropsychological functioning in young psychiatric outpatients was the best independent predictor of later functional outcome. There have also been many other cross-sectional studies which generally found that cognitive impairment was associated with poorer community outcome, and that cognitive impairment predicted community functioning better than positive symptoms or negative symptoms (Green, 2006; Green, Kern & Heaton, 2004; Rajji et al., 2014; Schmidt et al., 2011; Sergi et al., 2006). In support of this, a meta-analysis by Fett et al. (2011) found moderate correlations between cognitive functioning and community functioning, social behaviour and theory of mind. There is further evidence using structural equation modelling that social cognition is actually a mediator variable between neurocognition and functional outcome (Schmidt et al., 2011; Sergi et al., 2006).

This may be news to you because even if you work in mental health, you probably know that all the treatment and outcomes of patients with schizophrenia are focused on their positive symptoms. The importance of managing the positive symptoms shouldn’t be trivialised; however, we need to recognise and communicate to others the unique contribution that understanding cognitive functioning and neuropsychology make to patient care in mental health.

A paradigm shift is required (and has started) in psychiatry whereby patient management, particularly for more chronic psychotic illnesses, is changing. Standard practice, led by the psychiatrists, has primarily targeted improvement of positive symptoms through medication. But as we now know, this is not the most important thing functionally (Kahn, 2020); nor is it the main thing mental health consumers want to change about their lives. The change taking place is a more integrative and multidisciplinary approach which targets not only the biological needs but also the social, cognitive and psychological needs of the patient. It makes sense that to improve community outcomes and day-to-day functioning, you need to target the area that causes the most ongoing impairment. Shifts in treatment targets could mean more functional gains and the maintenance of these gains will significantly reduce the extent of disability that mental health consumers face. The ultimate goal is to support mental health consumers to lead more fulfilling lives.

Neuropsychologists are well placed to significantly impact a patient’s outcome firstly by providing an assessment which outlines their cognitive strengths and weaknesses, informs their care and assists them in navigating the world, based on their skills. We can also provide intervention which can assist in improving their skills to maximise their outcomes.

Contact the first author: [email protected]

Sarah would like to offer thanks to Dr Lainie Hart, clinical neuropsychologist and clinical lead of neuropsychology at The Canberra Hospital, who provided consultation and inspiration for earlier versions of this work.