Don’t ignore the skeleton in the psychiatric closet

Williams et al. (2016) explore links between brain and bone health from physiological and epidemiological perspectives. Their commentary provides a helpful reminder that psychotropic medications can adversely impact bone health and highlights the many risk factors associated with poor bone health that are also linked with mental disorders. They suggest that quantitative heel ultrasound, in lieu of dual-energy X-ray absorptiometry (DXA), may provide a useful index of bone mineral density and that further research is required to enable clinical recommendation. We provide comment on the impact of psychiatric disorders on bone health and the implementation of physical health promotion in people with mental illness. We then review current recommendations for bone mineral density surveillance in people with mental illness.

Psychiatric disorders negatively impact bone health. Williams et al. (2016) point to the consistent evidence of high prevalence of vitamin D deficiency and insufficiency in people with schizophrenia and depression. Indeed, any mental disorder that restricts nutrition or outdoor activity (and thus exposure to ultraviolet radiation) would be associated with vitamin D deficiency; people with dark skin or women who are veiled are at particularly high risk. A paradigmatic example of mental illness contributing to bone disease is anorexia nervosa and its complication of osteopenia (Hay et al., 2014). Tobacco use disorder and alcohol use disorder are two more psychiatric conditions with biologically graded, plausible and temporal relationships with osteoporosis. On the weight of available evidence, we argue that proximal bone health risks from these, and other, psychiatric disorders take primacy over the distal cumulative risks posed by psychotropic medication use. As Williams et al. (2016) state, evidence is not yet available to guide psychotropic treatment choice within class with respect to bone health. Judicious effective treatment of psychiatric disorders is necessary, but care should be taken to ensure that bone health is also considered.

We endorse Williams et al.’s (2016) proposal of indicated primary prevention of osteoporosis in people with mental illness via promotion of weight-bearing exercise in addition to adequate calcium and vitamin D intake. Physical health protocols need to be routinely implemented for people with psychosis (Shiers and Curtis, 2014). Supplementing such protocols with advice from expert organisations should be considered (Osteoporosis Australia [OA], Scientific and Advisory Committee, 2014: 6). Finally, there is an imperative to ensure bone health, as part of general health, be included in primary and mental health professional training programmes and in clinical practice guidelines.

Secondary prevention of osteoporosis by screening particular groups of people with mental illness is recommended. The Royal Australian and New Zealand College of Psychiatry recommends DXA biennially for people with anorexia nervosa (Hay et al., 2014). OA also recommends DXA for people over 50 years of age with a major depressive disorder or who use a selective serotonin re-uptake inhibitor (SSRI) or antiepileptic medication (OA, Scientific and Advisory Committee, 2014: 4). Despite this, mood and psychosis disorder safety monitoring guidelines do not emphasise bone health (Williams et al., 2016). The addition of quantitative heel ultrasound as a validated bone density screening method may be a safer and cheaper alternative, but DXA remains the gold-standard test for bone mineral density. Tertiary prevention of the complications of osteoporosis in people with mental illness is best provided in collaboration with other medical specialists (OA, Scientific and Advisory Committee, 2014: 8).

Finally, mental disorders and bone health have a bidirectional relationship. Osteoporosis-related bone fractures can be associated with an increased risk of depression (Nightingale et al., 2001). Improved bone health in the general population may result in unanticipated benefits for mental health.