Substance Use in Early Psychosis: Mixed Methods Impact on Family.

Identifying diagnostic biomarkers of Parkinson's disease (PD) is the subject of much ongoing research, particularly those that may predict development, or help to diagnose disease earlier. One early non-motor symptom is seborrheic dermatitis: excessive sebum (a waxy, oily biofluid) excreted from the sebaceous glands in patients with PD. This is associated with lipid dysregulation and could potentially be used as an indicator for the disease. Sebum has been noted to have a distinctive odor in repeated blinded studies with Joy Milne, who has hyperosmia. Dogs have been trained to detect the scent of many human diseases from prostate cancer to malaria and Covid-19. In a prospective, diagnostic case-control study, three trained dogs were tested on sebum samples from PD patients, and matched controls. Using the diagnostic criterion of two of the three dogs alerting, sensitivity and specificity rates of 91% and 95% to medicated and 89% and 86% to drug naïve samples, respectively were achieved. Holt and Johnston saw similarly high levels in a mixed-breed cohort of 23 home-owned dogs (86% sensitivity and 89% specificity). The authors concluded that trained dogs could be a useful, quick non-invasive and cost-effective method to identify patients with PD, but they provided limited information on the dog's training and testing. In the current study, we further tested the capacity of trained dogs to detect PD using sebum swabs. Since the dogs are effectively the measuring instrument, it is important to provide full details of their training, calibration and testing. To simulate real operations, unlike Gao et al., we did not use precisely matched-control samples. However, since it is vital to minimize all confounding factors, we trained dogs using samples taken shortly after diagnosis and a control group ranging from healthy individuals to patients with other neurological conditions. Dogs were trained by a professional dog trainer (MS) using an established protocol and then tested during double-blind trials. Ethical approval was obtained by the NHS Health Research Authority (IRAS project ID 191917, REC reference: 15/SW/0354). Parkinson's disease participants (diagnosed by a Movement Disorder specialist as fulfilling the UK Brain Bank criteria) were recruited from 25 different NHS Dry skin swabs were collected as described in Supplemental Material 1 and by Hoare et al. Control samples were collected from people accompanying people with Parkinson's (PwP) to clinics and from volunteers attending the Medical Detection Dog Centre.