Cognitive impairment or dementia is increasing in prevalence worldwide and may be an unrecognised and early complication of a number of endocrine conditions, including diabetes mellitus and thyroid disease. In addition, these conditions may be predisposing factors towards developing dementia. In this chapter, we will discuss these issues with reference to diabetes in particular, being the endocrine disorder with the strongest association with cognitive impairment. Identifying cognitive impairments among people with endocrine disorders is important, as is identifying endocrine conditions in people living with dementia, as this may require adjustment of therapeutic targets and of treatment. There are particular challenges in certain clinical groups, including depressive pseudodementia, behavioural and psychological symptoms of dementia, frailty and mild cognitive impairment. Targets for glycaemic control may need to be relaxed in this group of patients, and this is supported by international best practice guidelines.

Depression is a common mental illness that is receiving increasing clinical, academic and even political attention. The World Health Organization (WHO) stated in its report of 2004 that depression is one of the most significant health challenges of the twenty-first century in terms of its effect on disability and loss of function, and it ranked depression as the third leading cause of burden of disease worldwide, as measured by disease-adjusted life-years. It is the leading cause of disease burden in the Americas, and is projected to be the leading cause of disease burden worldwide by 2030. In addition to being an important condition in its own right, it is increasingly being recognised as a condition that, when comorbid with physical illness, has a significant effect on recovery and even mortality. Comorbid mental disorders with endocrine conditions may present challenges both for the patient and for their healthcare providers. The evidence for effective joint interventions is at an early stage, and individuals with psychiatric disorders often experience inequalities in accessing routine physical healthcare.

Eating disorders, while relatively rare, have the highest mortality rates of all mental disorders. When combined with diabetes, they have poor outcomes in terms of recurrent diabetic ketoacidosis, premature development of microvascular complications and mortality. Eating disorders are common in diabetes and, where present, are associated with a much higher incidence of diabetic complications and a sevenfold increase in mortality. The term ‘diabulimia’ is increasingly used by patient groups and in the general (and social) media. However, it is not a diagnostic term; there has been no professional agreement regarding what constitutes ‘diabulimia’ or what may constitute a minimum set of criteria for diagnosis. It is important for endocrinologists to have a high index of suspicion for eating disorders in patients with diabetes (especially young women with type 1 diabetes). Psychiatrists need to consider and treat insulin omission as a form of purging in eating disorders.

Modern developments in research and in the development of services have demonstrated the need for the better integration of mental and physical healthcare in various areas of medicine, including endocrinology. Years of research into the aetiology of depression and other mental disorders have demonstrated the importance of the stress response and the hypothalamic–pituitary axis in the aetiology of many common mental disorders. Where collaborative care or integrated care systems or interventions have been implemented, they have shown improved outcomes across the domains. There is a need for more naturalistic research in the management of complex comorbidities.

Suicide is a leading cause of death in many Western countries. Suicidal ideation and behaviours can be symptoms of depression, but they are also seen in people with other mental health problems, such as bipolar affective disorder, psychosis, substance abuse disorders and adjustment disorders. They are also seen in people who present with psychological distress rather than any diagnosable mental disorder. The consequences of suicidal acts may be especially serious in people with diabetes given the accessibility of lethal means on the one hand, but also the heightened risk of developing complications in cases of severe self-neglect due to a more passive death wish on the other. In Chapter 2, we discussed the relationship between depression and endocrine disorders. Although depression is associated with suicidal ideations and behaviours, it will be these symptoms rather than a diagnosis of mood disorder that are the focus of this chapter.

Given the high rates of diabetes being comorbid with many mental health conditions, it is no surprise that diabetes is very common in mental health facilities and settings. When the mortality gap in severe mental illness is considered, along with the fact that cardiovascular diseases (including diabetes as a cardiovascular risk factor) contribute greatly to this mortality gap, the importance of acting to reduce the impact of suboptimally managed diabetes in these settings is clear. Specific measures may be required to ensure that patients in these settings receive the usual standard of care. Factors such as acuity of illness, lack of insight into both mental and physical health problems and practical difficulties in attending appointments may mitigate against optimised diabetes management. This chapter considers specific challenges particular to various settings, and we will consider some measures that may help to ameliorate or fully overcome these barriers to optimised care. We will consider specific measures in various types of residential units and other settings (including inpatient settings), and we will explore different initiatives that have been used to overcome these challenges and close the mortality gap

People who are transgender and gender non-conforming (TGNC) include people whose experienced gender is different from their assigned sex at birth, and they have specific healthcare needs. As the number of people identifying as TGNC is increasing internationally, it is important that endocrinologists, psychiatrists and indeed all health professionals have a good understanding of the issues related to the physical and mental healthcare of transgender people. People who identify as TGNC experience a disproportionate amount of violence, discrimination and stigma, and these factors contribute to poorer outcomes. There is also a high rate of comorbidity in young people who are TGNC, including mood disorders, eating disorders, suicidal ideation and self-harm. Compounding these mental health problems are the effects of social exclusion (including educational and employment), which often places TGNC people at risk, especially during transitioning. Transgender people should have access to expert guideline-based care that allows them to transition safely and to optimise their health and well-being.

The majority of endocrine conditions can be successfully managed with long-term treatment, whether that be in the form of medication or lifestyle factors. In order for treatment to be effective, adherence to the treatment regime is key. Central to the concept of adherence is the presumption of an agreement between prescriber and patient about the prescriber’s recommendations. Non-adherence occurs when a patient does not initiate a new prescription, implement it as prescribed or persist with treatment. The World Health Organization (WHO) has posited that, in general, there are five dimensions to adherence, all of which can impact on rates of non-adherence: condition-related factors, health system factors, socio-economic factors, therapy-related factors and patient-related factors. While these dimensions are not entirely independent of each other, this serves as a useful means for organising the broad range of factors that can contribute to non-adherence.

The primary endocrine effectors of the stress response are located in the paraventricular nucleus of the hypothalamus, the anterior lobe of the pituitary gland and the adrenal gland. These structures are referred to as the hypothalamic–pituitary–adrenal (HPA) axis. In the setting of stress, corticotrophin-releasing factor induces the release of adrenocorticotropic hormone, which stimulates the synthesis and secretion of glucocorticoids from the adrenal gland. Glucocorticoids exert a wide range of effects and can influence cardiovascular function, immunity and inflammation, metabolism, reproduction and fluid volume. An important target organ is the brain, where glucocorticoids can affect neuronal differentiation and excitability, behavioral reactivity, mood and cognition. This regulatory system works in conjunction with the sympatho-adrenal medullary system, which releases catecholamines, including noradrenaline and adrenaline. These systems are crucial for dealing with both physiological and psychological stress and restoring our steady state. Inappropriate regulation of the stress response has been linked to a wide array of pathologies, including hypertension, diabetes, osteoporosis and psychological disorders. In this chapter, we will focus on disorders of the HPA axis and their effects on mental health.