The prevalence of mental disorders among children, adolescents and adults in the Western Cape, South Africa

Objective: To provide estimates of the prevalence of selected mental disorders in the Western Cape, based on the consensus achieved by a working group established for this purpose. Method: An expert working group was established to provide technical expertise for the project. Potential risk factors likely to influence local prevalence rates were identified. Annual prevalence rates for adults and for children and adolescents were derived by consensus, informed by a systematic literature review. Prevalence rates were derived for individual disorders and adjusted for comorbidity. Results: The overall prevalence was 25.0% for adults and 17.0% for children and adolescents. Conclusion: Prevalence rates of child, adolescent and adult mental disorders were derived in a short period of time and with the use of minimal resources. Although of unknown validity, they are useful for policy development and for planning service utilisation estimates, resource costing and targets for service development for local mental health needs. This in the absence of an existing methodologically sound national prevalence study. We recommend that policy and programme developers draw on the expertise of local academics and clinicians to promote research-informed planning and policy development in the public sector. South African Psychiatry Review Vol. 9(3) 2006: 157-16

A hypothetico-deductive approach to assessing the social function of chemical signalling in a non-territorial solitary carnivore

The function of chemical signalling in non-territorial solitary carnivores is still relatively unclear. Studies on territorial solitary and social carnivores have highlighted odour capability and utility, however the social function of chemical signalling in wild carnivore populations operating dominance hierarchy social systems has received little attention. We monitored scent marking and investigatory behaviour of wild brown bears Ursus arctos, to test multiple hypotheses relating to the social function of chemical signalling. Camera traps were stationed facing bear ‘marking trees’ to document behaviour by different age sex classes in different seasons. We found evidence to support the hypothesis that adult males utilise chemical signalling to communicate dominance to other males throughout the non-denning period. Adult females did not appear to utilise marking trees to advertise oestrous state during the breeding season. The function of marking by subadult bears is somewhat unclear, but may be related to the behaviour of adult males. Subadults investigated trees more often than they scent marked during the breeding season, which could be a result of an increased risk from adult males. Females with young showed an increase in marking and investigation of trees outside of the breeding season. We propose the hypothesis that females engage their dependent young with marking trees from a young age, at a relatively ‘safe’ time of year. Memory, experience, and learning at a young age, may all contribute towards odour capabilities in adult bears

Energetics reveals physiologically distinct castes in a eusocial mammal

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A Field Study of Wild Echidna Responses to Conspecific Odour

Mammalian olfactory cues play a crucial role in coordinating matingbehaviour as they contain pertinent information on sex, reproductive status andreceptivity to mating. Males of many species are particularly attentive tochanges in female odour cues, as these can be used to find potential mates andmonitor changes in reproductive condition. Such sensitivity is likely to beespecially important for usually solitary or seasonally breeding individuals. Weused remote scent trials in the field to examine if wild short-beaked echidnas areattracted to conspecific female odour. Our results are consistent with thehypothesis that male echidnas use olfactory cues during the breeding season tolocate females: Echidnas were only observed investigating female odour samplesand not empty camera trap stations, more echidnas (including knownindividual males) were attracted to female odours during the breeding season,than during the non-breeding season and we noted olfactory behaviours such assniffing and tongue-flicking at the odour source. Male echidnas increase theirmating opportunities by engaging in scramble competition and being sensitive tovolatile and non-volatile female odour components, allowing them to locatepotential mates and minimise search costs. Consequently, male ability to locatefemales may be sexually selected, but further bioassays, along with geneticinformation, is needed to investigate this further