Cannabis is a widely used drug, which effects on human health remain controversial. Recent studies have found correlations between cannabis use and brain structural changes that may be related to ageing processes. Eotaxin-1 is a chemokine described as a marker of ageing, which also appear to increase with cognitive deficits and neurogenesis. Here, we aimed at characterising the effect of cannabis in accelerating normal ageing processes, by studying eotaxin-1 plasma levels in people who currently use cannabis, have used cannabis in the past, or have never used cannabis.

A total of 87 healthy volunteers participated in the study. Participants completed the Cannabis Experience Questionnaire, the General Practice Physical Activity Questionnaire, the Sociodemographic, Morphometric, Alcohol and Tobacco Questionnaire, and provided a blood sample. Eotaxin-1 was assessed by ELISA. The three groups were compared using one-way ANOVA to assess levels of eotaxin-1, and nonpaired Student t-tests to assess other factors effects.

Current users of cannabis (n=18) had significantly higher eotaxin-1 plasma levels compared to past users of cannabis (n=33) and individuals who never used cannabis (n=36). The latter two groups had similar eotaxin-1 levels. Higher eotaxin-1 plasma levels were not attributed to gender, age, body mass index, physical activity or use of other legal/illegal drugs.

These results suggest that cannabis use increases eotaxin-1 plasma levels and could result in accelerated brain ageing. However, the effects appear to be reversible when cannabis use ceases. These findings have important implications for treatment and care of mental health disorders, such as schizophrenia.

Psychotic disorders are highly heritable such that the unaffected relatives of patients may manifest characteristics, or endophenotypes, that are more closely related to risk genes than the overt clinical condition. Facial affect processing is dependent on a distributed cortico-limbic network that is disrupted in psychosis. This study assessed facial affect processing and related brain structure as a candidate endophenotype of first-episode psychosis (FEP).

Three samples comprising 30 FEP patients, 30 of their first-degree relatives and 31 unrelated healthy controls underwent assessment of facial affect processing and structural magnetic resonance imaging (sMRI) data. Multivariate analysis (partial least squares, PLS) was used to identify a grey matter (GM) system in which anatomical variation was associated with variation in facial affect processing speed.

The groups did not differ in their accuracy of facial affect intensity rating but differed significantly in speed of response, with controls responding faster than relatives, who responded faster than patients. Within the control group, variation in speed of affect processing was significantly associated with variation of GM density in amygdala, lateral temporal cortex, frontal cortex and cerebellum. However, this association between cortico-limbic GM density and speed of facial affect processing was absent in patients and their relatives.

Speed of facial affect processing presents as a candidate endophenotype of FEP. The normal association between speed of facial affect processing and cortico-limbic GM variation was disrupted in FEP patients and their relatives.