Working with non-verbal patients initially was fundamental for helping Dr Stephen Moss produce universal mental disorder diagnostic interview scripts  assessments which the researcher argues have evolved over 30 years to become "more consistent, robust and valid" than those leant on by the majority of psychiatrists and psychologists.

"Clinicians, if they rely on their gut feelings, are not objective and they're not logical in the way they collect information."

The bible for diagnosing mental conditions in the west remains the Diagnostic and Statistical Manual (DSM) endorsed by the American Psychiatric Association. However its vulnerability to subjective interpretation invites occasional and sometimes angry criticism.

While the Moss-PAS 'psychiatric assessment schedules' are all questionnaires informed by and compliant with the DSM, according to Moss they lack its scope for ambiguity and error. The veteran mental health assessment trainer – the lead author of the respected training materials – says we need not take his word for it alone: the publications are now used by clinicians across the UK, US, Germany, Japan and elsewhere.

All the questions are framed in the same way, with an initial basic question followed by a series of suggested probes. The fundamental aim is to conduct a targeted discussion about the symptom, from which it is decided: a) Is the symptom present? B) If it is present, how severe is it?

Moss argues that in providing a structure for interviews, with reference points for what severity is characterised by, his diagnostics go further than the DSM and the World Health Organisation’s own International Classification of Diseases (ICD), and prevent diagnoses from differing according to who happened to conduct the interview and their own particular interpretation of what they observed.

The DSM merely offers "rules" about a condition, the researcher claims, highlighting depression to make his point. "It says that in order for somebody to meet the criteria, they should have at least one of the core symptoms of depression, which they define as loss of interest and depressed mood. So you've got to have one of those and then you ought to have some other symptoms [too].

"That’s as far as the classification systems go. What they don't tell you is how severe the symptoms have got to be. They don't necessarily tell you exactly how many symptoms you have to have [or] give you guidance on how you would decide whether someone has got a mild loss of interest, moderate loss of interest, or severe loss of interest. Those are not talked about at all."

"What an assessment like mine does is to help in several different ways: It helps clinicians with formulating the assessment interview questions to make questions tightly related to the information you need to get; it gives you guidance on what a typical example of a symptom would look like in different levels of severity; and it gives you a way of scoring it all up. The latest addition to this is that my digital versions do all the scoring for you and produce a report, sent to your email address."

What makes the Moss tools stand apart is their guidance for qualifying, but particularly quantifying, evidence of each displayed symptom. In measuring the severity of Generalised Anxiety Disorder, a patient will be asked to share precisely how many hours their sleep was disturbed by, and which parts of the body they have experienced muscle tension, and for how long. How to measure many other experiences is also detailed.

Conditions covered by the Moss-PAS assessment schedule:

ICD-11

  • Agoraphobia
  • Social phobia
  • Panic disorder
  • Generalised anxiety disorder
  • Obsessive compulsive disorder
  • Depressive episode
  • Depressive episode with psychotic
  • features
  • Manic episode
  • Manic episode with psychotic features
  • Schizophrenia
  • Schizoaffective disorder
  • Delusional disorder
  • Acute and transient psychotic disorder
  • Autism spectrum disorder

DSM-5

  • Agoraphobia
  • Social phobia
  • Panic disorder
  • Generalised anxiety disorder
  • Obsessive compulsive disorder
  • Depressive episode
  • Depressive episode with psychotic
  • features
  • Manic episode
  • Manic episode with psychotic
  • features
  • Schizophrenia
  • Schizoaffective disorder
  • Schizophreniform disorder
  • Delusional disorder
  • Psychotic disorder NOS
  • Brief psychotic disorder
  • ADHD
  • Autism spectrum disorder

Heritage and innovation

International take-up of the tools has been hard earned – and has come through decades of development. "The Moss-PAS system is designed to support clinical expertise, not to replace it. It all started when I was working at the Hester Adrian research centre at Manchester University in the late eighties in the field of problems of ageing in people with learning disability. The Department of Health asked if we could run a project looking at mental health problems in people with a learning disability."

"At that time, the world had made very few inroads into thinking about how you could assess the mental health of somebody who may not even be able to talk to you. We decided that what we needed was an interview that our psychiatrist could use with everyone over 50 and if he couldn't talk to him at all, it [the script] had to be able to be used with a key informant: a parent or another individual."

"We started with an existing assessment of ‘present state’ examination. There was already a simplified version of that called the psychiatric assessment shadows, known as the ‘PAS’. And one of my clinical colleagues came up with the bright idea we could call it the PASS-ADD, partly because we had added to it, but also because the ‘ADD’ stands for adults with developmental disabilities. That's how the name was born and over the years it became synonymous with mental health assessment in adults with intellectual disability."

"The reason for the name change is because it wasn't long after we started doing this work that people asked about children and adolescents and we developed a modern version for them. It then became clear - as the years went by and these assessments became more and more refined as I worked with thousands of users all over the world - that they really were equally useful for the general population, if you want to do that."

"The reason that people don't usually want to do something different with the general population is because they think, 'Oh, well, the patient can talk to me so I don't need any other information or sophisticated things like this'. But in fact the same issues apply: clinicians, if they rely on their gut feelings, are not objective and they're not logical in the way they collect information."

"So we changed the name. We went to the idea of Moss-PAS, not to aggrandise me, but to reflect the fact that they were not specifically about intellectual disability."

Empowering earlier, more therapeutic, interventions

People can wait years for the correct diagnosis. But for conditions like schizophrenia an intervention has been found to be far more likely to succeed if it made within weeks of symptoms being presented. Diminishing returns can be confounded by expanding the pool of practitioners that are equipped to make diagnoses.

"There's some sort of [perceived] understanding that a more sophisticated interview would only be used by a psychiatrist or a psychologist, but that's not actually true," Moss insists. "Anybody can be taught how to be a good interviewer. Of course the extent to which they would then go on to be able to interpret the results obviously depends on their background, but there are no barriers. I've never put up any barriers for who should be allowed to be trained to use the tools."

Carers and family members can make use of the basic ‘checklist’ questionnaire manual for screening possible mental illness for further exploration. Nurses and psychiatrists alike are encouraged to use the more thorough Moss-PAS psychiatric assessment schedule. Moss emphasises how nurses and support workers employed in learning disability settings can and should expect to play a diagnostic role with their patients.

"For people with any degree of cognitive impairment it's often very difficult to identify a mental health problem because of the person's behaviour. In the time that I've been working I've seen that you get a lot more service staff now who have sophisticated knowledge about mental health problems. Their services might have a policy that involves doing a Moss-PAS assessment on someone they support. If it turns out that they've got conspicuous mental health problems which they feel need specialist treatment, they then might seek psychiatric help, which might be through learning disability psychiatry or general psychiatry."

Whether the individual has a learning disability or not, patients all too often are misdiagnosed by clinicians who have been trained using the DSM or ICD. "Diagnoses like autism, in my opinion, get handed around like lollypops but they are not always made on very firm clinical grounds and they don't always help us understand how we can help a person," Moss continues.

"The problem with making a diagnosis is that it very often becomes the single point around which everybody tries to explain why the person is having their problems and all the behaviours that they experience. I think this applies to a diagnosis of autism and it applies to a diagnosis of personality disorder. Very often, it takes away the focus from the everyday issues that people have like whether they've got friends, whether they've got support, whether they feel lonely, whether they feel loved. And then very often these things get missed."

Affirming diagnoses

Moss says that accurate disorder diagnoses can be both empowering and comforting for people wrestling with mental health challenges. "Mental illness is the glasses through which you look out on the world. Mental illness is inescapable. Physical illness, if there’s no pain, you can still have a good quality of life with it. But you wake up with mental illness and that's how you see it and it reduces your quality of life."

"With people who receive a diagnoses, you see them say it’s ‘changed their life’. This is because it’s given them a reason for what they are experiencing. Even though a diagnosis doesn’t actually provide a reason as such, it makes them feel less alone. It make them feel that there are other people who are going through what they are going through."

"The reason that the Moss-PAS system has become so good is explained both by the length of time that I've been continuing to develop it [over 30 years] and by the fact that everything I've learned about this field has come from all those people I’ve worked with: seeing how they have problems, seeing what their knowledge and expertise is, seeing what I might have missed."

"When I train people I develop clinical examples and invite others to assess these. Very often I'll produce what I think my answers are and then very often people will argue with me about what the answers should be. And very often they'll be right."

Further information, including how to order the updated Moss-PAS psychiatric assessment schedule, is available here.

A version of this article also appears on our sister site, Mental Health Today.

The Moss-PAS training materials are published by Pavilion Publishing and Media, owners of the Learning Disability Today and Mental Health Today websites.