Psychological methods for the assessment of chronic toxic encephalopathy and multiple chemical sensitivity

The dissertation deals with psychological methods aimed at improving the understanding and assessment of two disorders related to contact with chemicals: solvent-induced chronic toxic encephalopathy (TE) and multiple chemical sensitivity (MCS). The main aim of Paper I was to study whether the addition of some newer psychological tests of complex attention and executive functions to a traditional test battery would improve the detection of TE. An improved detection of TE could not be demonstrated. However, while most TE cases with previous clear deviations in neurobehavioral tests (TE 2B) showed a stable impairment at re-testing, cases without previous deviations (TE 2A) were unstable at re-testing, which suggests that repeated examinations might improve the assessment. Paper II showed that a sample of Swedish MCS cases did not have any obvious deviations in the neurobehavioral test battery. Paper III demonstrated that the Swedish MCS sample had a partially elevated mental distress profile in the Symptom Checklist 90, similar to previous reports on North American MCS cases – a profile much lower and more limited than found among Swedish TE cases. The TE group had elevations on several anxiety- and aggression-related scales of the Karolinska Scales of Personality trait inventory, while the MCS sample scored slightly higher than referents on only one single anxiety scale (psychasthenia). Neither group showed any deviation in the personality test Meta-Contrast Technique. Neither the TE nor the MCS group showed higher than normal ratings of health risks from environmental threats, thus not supporting a cognitively based generalized fear of ambient factors as a factor of importance in MCS. In Paper IV and V the smell intolerance reactions common in TE cases were explored, aiming to develop a standardized chemical challenge design for the assessment of chemical intolerance. The annoyance reactions of TE cases was successfully reproduced during controlled chemical challenge at exposure levels below known levels for acute CNS-effects and trigeminal irritation. However, a corresponding performance reduction in neurobehavioral tests was not observed. Neither annoyance level nor test performance was related to the neurotoxic properties of the solvents used during the challenges