Handbook of Solvents - George Wypych - ChemTech - Ventech!

20.2 Cognitive and psychosocial outcome 1331
misdiagnosed and their “symptoms” were due to some other cause or were “normal” for
them, or that there were psychosocial difficulties present at the first assessment which exacerbated
the organic symptoms and resolved with rehabilitation. The disturbing message is,
however, that the symptoms of Type 2 OSN are often persistent, and in these cases probably
permanent. Even in those individuals where improvement occurs, their symptoms rarely resolve
completely.
There was no association between improvement on neuropsychological tests and either
time between the two assessments or total time away from solvents. There was no correlation
between the exposure score and severity at diagnosis or extent of recovery, and
there was no association between a past history of peak exposures and either severity at initial
diagnosis or change on neuropsychological assessment. A recent review 18 of studies
looking at whether the degree of impairment is related to the dose severity concludes that although
several studies have demonstrated significant dose response relationships, there are
disturbing inconsistencies, with some studies showing no relationship, 19,20 and one study
showing a dose response relationship in painters with levels of exposure considerably lower
than the negative studies. 21 Methodological problems and differences and different research
populations probably account for these inconsistent findings, and more research is clearly
required.
20.2.6 INDIVIDUAL DIFFERENCES IN SUSCEPTIBILITY TO OSN
One possible reason for the inconsistent findings both across and within studies examining
the relationship between exposure levels and OSN symptoms, may be that individuals have
different susceptibilities to solvents. It is not uncommon to diagnose one worker with moderate
Type 2 OSN, yet find no symptoms or serious complaints whatsoever in his workmate
who has worked by his side in the same spray painting workshop for twenty years. On closer
assessment it may be discovered that the affected worker sustained a number of minor head
injuries in his younger football-playing days, or has smoked a marijuana joint every weekend
for the past 20 years. Subclinical neuronal damage caused by previous insults, or even
by normal aging, may make an individual more susceptible to OSN. Another possibility is
that some people are biologically, and even genetically more susceptible to solvents. In this
sense, OSN can be likened to the post-concussional syndrome following a mild to moderate
traumatic brain injury. 6 Not only are the psychological and neuropsychological symptoms
very similar, but for reasons which cannot be explained simply by lifestyle differences or
malingering, individuals appear to differ widely regarding their susceptibility to developing
a post-concussional syndrome. In illustration of this, a recent study reports varying outcomes
from apparently equivalent head injuries in a group of athletes. 22
20.2.7 PSYCHOSOCIAL CONSEQUENCES OF OSN, AND REHABILITATION
The common psychological and physical symptoms of OSN of fatigue, irritability, depression,
sometimes aggression and violence, headaches, and hypersensitivity to noise and alcohol,
along with memory difficulties, poor concentration, poor motivation, and slowed
thinking, are a recipe for disaster in interpersonal relationships. Thus it is not uncommon for
workers to be diagnosed and treated first for a psychiatric disorder (especially clinical depression)
and for their marriages to break up, before they are even suspected of having
OSN. 6,10 Once OSN is diagnosed, the prospect of losing their job is a grim one for most victims,
most of whom are tradesmen in middle age or older who may have difficulty obtaining