Chronic hepatitis C (CHC) represents a significant personal and public health burden:
worldwide, 1,750,000 new infections and 400,000 deaths from CHC and its consequences[1] occurred in 2015. The prevalence estimate, on a global scale, is about 200 million
people affected.
Involvement in patients with CHC presents with a broad spectrum of signs and symptoms[2],[3],[4]. Among the possible consequences of central nervous system (CNS) damage, neuropsychiatric
disorders are of pivotal importance not only because of their intrinsic relevance,
but also because they can easily be missed.
Among the cognitive dysfunctions, concentration difficulties and slowed thinking stand
out, but other functions can be compromised as well (calculation, sustained attention,
information processing speed, memory and learning). On the psychiatric side, depression
is in the foreground, but other disorders are also frequent[2],[3],[4].
Similar to what occurs in other CNS diseases, the reactive component and primary biological
aetiology of depression are not easy to distinguish[4]. The feeling of pathological fatigue is also very common[4].
About the pathogenesis of cognitive disorders, there are EEG[3], structural and functional MRI data, PET and SPECT[2],[3],[4] data highlighting dysfunctions and damage to the frontal white matter, the cortical
and subcortical grey matter (e.g., basal ganglia). It has to be noted that several
of these data suggest the presence of inflammatory phenomena.
Based on numerous data, the aforementioned cognitive disorders are to be considered
an extrahepatic manifestation of CHC. It is still not clear whether brain damage is
the consequence of viral presence in the CNS or the result of extra- and intra-cerebral
immune activation: in CHC, the activation of immune mechanisms occurs at both systemic
level and cerebral level, regardless of the presence of the virus[3].
The link between active inflammatory processes within the CNS and cognitive dysfunction
has been demonstrated in HIV encephalopathy, multiple sclerosis (MS) and in more properly
degenerative diseases, such as Alzheimer's disease (AD). In MS, dysfunctions resulting
from inflammation are also linked to direct action on the synaptic function of inflammation
mediators[5].
In AD the role of inflammatory processes, not secondary to other pathophysiological
events but possible primary events, has been highlighted: the precise role of innate
and adaptive immunity in typical neuro-inflammatory diseases (e.g., MS) compared to
AD is not clear yet[6],[7].
Given the prevalence and serious consequences of CHC, the identification of therapies
able to reduce the presence of the virus in the body has been intensely pursued.
The first therapy with significant efficacy, based on Interferon (, is burdened by
not negligible side effects, precisely on psychiatric and cognitive functions[3],[8] even if other possible causes for those symptoms cannot be overlooked[9]. The advent of direct-acting antiviral (DAA) has been significantly appreciated.
The work of Gascon et al.[10] re-proposes the issue of cognitive impairment in patients with CHC and, notably,
examines the benefits of DAAs on cognitive functioning: the effects of therapy with
three DAAs on cognitive functioning and depression levels severity in a sample of
58 patients with CHC has been examined through three evaluations: before, immediately
after and six months after treatment. Cognitive assessment was based on a large series
of neuropsychological tests; depression and other aspects were also evaluated with
standardized tools. The sample was composed of subjects with HCV genotype 1 infection,
without significant liver damage and without serious comorbidities; despite this,
at the initial assessment, more than 70% had some degree of cognitive impairment;
at the six-month evaluation, subjects with preserved cognitive functions went from
27.5 to 50%; the cognitive domains in which a significant improvement was found were
episodic verbal memory and visuo-spatial memory. There was no significant improvement
in depression levels. Drug therapy has focused on sofosbuvir in various combinations
with simeprevir, daclatasvir and ribavirin.
This relevant study suggests several reflections. Cognitive disorders are quite common
in patients with CHC even without significant liver damage: therefore, the aetiology
of these disorders must be sought in direct brain damage.
DAA therapy allows the recovery of normal cognitive function without leading to significant
negative effects on other functional aspects (e.g., mood). Cognitive performance improvement
is not directly linked to depression improvement.
According to data from the study by Gascon et al.[10], cognitive impairment and its variations are not influenced by premorbid intellectual
capacity (cognitive reserve). The cognitive reserve, however, is a complex construct[11] that deserves a thorough evaluation.
The positive effects of DAA therapy on cognitive functioning are likely to be more
significant when treatment is instituted before cognitive impairment involves multiple
domains. This opens the discussion on the usefulness of an early cognitive screening
in all patients with HCV infection.
Other interesting perspectives are indicated by the work of Gascon et al.[10]: Are there any predisposing or protective factors towards the possible cognitive
impairment in patients with CHC (e.g., ApoE genotype) that are worth exploring? It would be interesting to follow CHC patients
longitudinally, distinguishing responders from non-responders to DAAs, to assess the
incidence of forms of dementia or other degenerative or inflammatory CNS diseases.
An in-depth investigation on the pathogenesis of cognitive disorders with further
studies of neuroimaging and neuro-transmitter variations also appear fundamental.
Equally important is to evaluate the correlations between cognitive disorders, fatigue,
resilience and psycho-emotional factors.
As always, a study, even well designed, provides not only some answers, but also,
perhaps more, new questions.
