Diet, physical activity and behavioural disinhibition in middle-aged and older adults: a UK Biobank study

Background and aimsBehavioural disinhibition is a prominent feature of multiple psychiatric disorders, and has been associated with poor long-term somatic health outcomes. Modifiable lifestyle factors including diet and moderate-to-vigorous physical activity (MVPA) may be associated with behavioural disinhibition, but their shared and unique contributions have not previously been quantified.MethodsN=157,354 UK Biobank participants who completed the online mental health assessment were included (age 40-69, 2006-2010). Using principal component analyses, we extracted a single disinhibition score and four dietary component scores (prudent diet, elimination of wheat/dairy/eggs, meat consumption, full-cream dairy consumption). In addition, latent profile analysis assigned participants to one of five empirical dietary groups: moderate-healthy, unhealthy, restricted, meat-avoiding, low-fat dairy. Participants self-reported MVPA in minutes/week. Disinhibition was regressed on the four dietary components, the dietary grouping variable and MVPA.Resultsin men and women, behavioural disinhibition was negatively associated with prudent diet scores, and positively associated with wheat/dairy/eggs elimination. In men only, disinhibition was associated with consumption of meat and full-cream dairy products. Comparing groups, disinhibition was lower in the moderate-and-prudent diet (reference) group compared to all other groups. Absolute βs ranged from 0.02-0.13 indicating very weak effects. Disinhibition was not associated with MVPA.ConclusionsAmong middle-aged and older adults, behavioural disinhibition is associated with multiple features of diet. While the observational nature of UK Biobank does not allow causal inference, our findings foster specific hypotheses (e.g. early malnutrition, elevated immune-response, dietary restraint) to be tested in alternative study designs.

Transcranial Direct Current Stimulation in the Treatment of Subacute Post-Stroke Thalamic Aphasia

Background: Although many studies have demonstrated the effectiveness of transcranial direct current stimulation (tDCS) in improving speech recovery in post-stroke aphasia, as far as we know patients affected by thalamic aphasia have never been investigated. Patient and method: A 65-year-old man with severe non-fluent aphasia due to a left thalamic haemorrhagic stroke underwent intensive daily speech therapy combined with tDCS. Results: The patient showed progressive improvement with almost complete recovery of his speech disorder, behavioural disinhibition and apathy. Conclusions: Our findings suggest that tDCS with concurrent speech therapy can be useful in patients with subcortical stroke lesions.

Childhood socioeconomic deprivation, but not current mood, is associated with behavioural disinhibition in adults

There is evidence to suggest that impulsivity is predicted by socioeconomic background, with people from more deprived backgrounds tending to be more impulsive, and by current mood, with poorer mood associated with greater impulsivity. However, impulsivity is not a unitary construct, and previous research in this area has focused on measures of ‘waiting’ impulsivity rather than behavioural disinhibition. We administered a standard measure of behavioural disinhibition, the stop-signal task, to 58 adult participants from a community sample. We had measured socioeconomic background using participant postcode at age 16, and assigned participants to receive either a neutral or a negative mood induction. We found no effects of mood on behavioural disinhibition, but we found a significant effect of socioeconomic background. Participants with more deprived postcodes at age 16 showed longer stop-signal reaction times, and hence greater behavioural disinhibition. The pattern was independent of participant age and overall reaction time. Greater behavioural disinhibition may be a consequence of experiencing childhood socioeconomic deprivation, and could play a role in maintaining social gradients in outcomes such as addiction.

Childhood socioeconomic deprivation, but not current mood, is associated with behavioural disinhibition in adults

There is evidence to suggest that impulsivity is predicted by socioeconomic background, with people from more deprived backgrounds tending to be more impulsive, and by current mood, with poorer mood associated with greater impulsivity. However, impulsivity is not a unitary construct, and previous research in this area has focused on measures of ‘waiting’ impulsivity rather than behavioural disinhibition. We administered a standard measure of behavioural disinhibition, the stop-signal task, to 58 adult participants from a community sample. We had measured socioeconomic background using participant postcode at age 16, and assigned participants to receive either a neutral or a negative mood induction. We found no effects of mood on behavioural disinhibition, but we found a significant effect of socioeconomic background. Participants with more deprived postcodes at age 16 showed longer stop-signal reaction times, and hence greater behavioural disinhibition. The pattern was independent of participant age and overall reaction time. Greater behavioural disinhibition may be a consequence of experiencing childhood socioeconomic deprivation, and could play a role in maintaining social gradients in outcomes such as addiction.

The effects of brain serotonin deficiency on behavioural disinhibition and anxiety-like behaviour following mild early life stress

Aberrant serotonin (5-HT) signalling and exposure to early life stress have both been suggested to play a role in anxiety- and impulsivity-related behaviours. However, whether congenital 5-HT deficiency × early life stress interactions influence the development of anxiety- or impulsivity-like behaviour has not been established. Here, we examined the effects of early life maternal separation (MS) stress on anxiety-like behaviour and behavioural disinhibition, a type of impulsivity-like behaviour, in wild-type (WT) and tryptophan hydroxylase 2 (Tph2) knock-in (Tph2KI) mice, which exhibit ∼60–80% reductions in the levels of brain 5-HT due to a R439H mutation in Tph2. We also investigated the effects of 5-HT deficiency and early life stress on adult hippocampal neurogenesis, plasma corticosterone levels and several signal transduction pathways in the amygdala. We demonstrate that MS slightly increases anxiety-like behaviour in WT mice and induces behavioural disinhibition in Tph2KI animals. We also demonstrate that MS leads to a slight decrease in cell proliferation within the hippocampus and potentiates corticosterone responses to acute stress, but these effects are not affected by brain 5-HT deficiency. However, we show that 5-HT deficiency leads to significant alterations in SGK-1 and GSK3β signalling and NMDA receptor expression in the amygdala in response to MS. Together, these findings support a potential role for 5-HT-dependent signalling in the amygdala in regulating the long-term effects of early life stress on anxiety-like behaviour and behavioural disinhibition.