Alterations in the visual system may underlie visual hallucinations in dementia with Lewy bodies (DLB). However, cortical excitability as measured by transcranial magnetic stimulation (TMS) and functional magnetic resonance imaging (fMRI) activation of lower visual areas (V1–3) to visual stimuli appear normal in DLB. We explored the relationship between TMS-determined phosphene threshold and fMRI-related visual activation and found a positive relationship between the two in controls but a negative one in DLB. This double dissociation suggests a loss of inhibition in the visual system in DLB, which may predispose individuals to visual dysfunction and visual hallucinations.

Nordsletten and colleagues1 report on the first study looking at assortative mating and psychiatric disorders in a representative population sample (of over 700 000). Compared with the general population, the odds of having a partner who also suffers from a mental health problem – both within and across disorders – were significantly elevated: cross-assortative mating was approximately 0.15 for bipolar disorder, 0.36 for substance misuse, and over 0.40 for attention-deficit hyperactivity disorder, autism spectrum disorder (ASD) and schizophrenia. Overall, having one of these disorders was associated with an approximately two- to threefold increase in the odds of having a mate with the same or an alternative mental health condition. Interestingly and importantly, such cross-assortative mating was not found for a range of physical health conditions, including diabetes, rheumatoid arthritis and multiple sclerosis.