Secondary Schizophrenia (10 page)

of external stimuli, although they possess other char-16% and frequent hallucinations in 2%. In contrast
Introduction – Section 1

to the hallucinations occurring in schizophrenia – in
most common – but in comparison to schizophrenia
which auditory hallucinations are more common
[6]
–
the hallucinations in that disorder were less severe and
among Ohayon’s group of interviewees who halluci-more commonly visual.

nated more than once a week during the daytime,
Hallucinations occur in a wide range of disorders,
the frequency was greatest in the olfactory modality,
as adverse reactions to or following intoxication with
followed by the tactile, and then auditory and visual
medications and nonprescription drugs and alcohol
modalities. In a large nonclinical population, Johns
and in response to sensory deprivation. Comprehen-and colleagues found auditory and visual hallucina-sive compendia of these causes associated with hallu-tions occurred in approximately 4% of the sample
[7].

cinations in different modalities can be found in Brasic
Such data support the proposition that just as there is
[21]
and Cummings
[22].

a range of mood and anxiety symptoms in the general
population, there is a continuum of psychotic symp-

Prevalence of hallucinations in

toms
[8–9]
. This is strongly advocated by van Os and
colleagues
[10].
Evidence from a number of cogni-

organic disorders

tive neuropsychiatric studies suggests that individuals
In contrast to the relatively high prevalence of hallu-with hallucination-proneness appear to attribute inter-cinations in populations of psychiatric patients, espe-nal events as external, and to have an external locus
cially those with serious psychiatric disorders, sec-of control for internal and interpersonal events
[11–

ondary or organic hallucinations are uncommon in
13]
. This appears to occur for both auditory and visual
general psychiatric practice. Cornelius and colleagues
hallucinations
[14].

reviewed more than 14,800 patients over a four-year
period who had been assessed at the Western Psy-

Prevalence of hallucinations in

chiatric Clinic, Pittsburgh, Pennsylvania, USA, where
retrospective analyses revealed only 11 patients with
psychiatric disorders

organic hallucinosis
[23].
These patients were distin-The disorder in which hallucinations are most com-guished from those with schizophrenia in that visual
mon is schizophrenia. It is generally well accepted that
hallucinations were the only symptom that was present
60% to 70% of individuals with this disorder experi-to a significantly greater degree in the organic group.

ence hallucinations
[15].
Auditory hallucinations are
Other distinguishing symptoms including flat affect,
most common, followed by visual hallucinations fol-thought disorganization, self-neglect, speech pressure,
lowed by tactile, olfactory and gustatory hallucina-and bizarre behavior all occurred more frequently in
tions: in 117 consecutively admitted patients studied
schizophrenia.

by Mueser and colleagues, the lifetime prevalence of
Although there is extensive literature on halluci-hallucinations for auditory, visual, tactile, and olfac-nations in individual modalities – as reflected in the
tory/gustatory hallucinations was 72%, 16%, 17%, and
sections that follow – there are relatively few papers
11%, respectively
[6].
Another study by Bracha and
that compare the phenomenology of organic halluci-colleagues suggested that the rate of visual hallucinosis and hallucinations due to primary psychiatric
nations in chronic schizophrenia might be as high
disorders such as schizophrenia and bipolar disorder.

as 32%
[16].
Rates described for auditory hallucina-The best information on the distinction between these
tions range from 47% to 98% of schizophrenia patients
two broad classes of hallucinations comes from older
[6, 16–19],
visual hallucinations from 14% to 69%
[6,

studies that contrast the presenting features of organic
16–18],
and tactile hallucinations from 4% to 25% of
and nonorganic psychosis. One of the most quoted
patients
[6, 16].

studies in this regard is the investigation by Cutting of
Hallucinations also occur in mood disorders. One
74 patients who suffered from acute organic psychosis
study of 4,972 hospitalized patients
[20]
showed that
and 74 patients with acute schizophrenia
[24].
The
the prevalence of hallucinations in mood disorder
causes of the organic psychosis included stroke,
patients was considerably greater for bipolar patients
epilepsy, carcinoma, respiratory failure, and alcohol
than for those with unipolar disorder (23% bipolar
abuse. Of the 74 patients with organic psychosis, 25

mixed, 11% bipolar manic, 11% bipolar depressed, and
had visual hallucinations compared with 13 with audi-6% unipolar vs. 61% schizophrenia). As in schizophre-tory hallucinations. In subjects with schizophrenia the
22

nia, in bipolar disorder, auditory hallucinations were
frequencies were reversed – 25 patients had auditory
Chapter 3 – Secondary hallucinations

hallucinations and 12 had visual hallucinations
[24].

laden experience. However, such a one-dimensional
Additionally,

first-rank

auditory

hallucinations

model does not capture the full range of possible
occurred in 22% of patients with schizophrenia and
abnormal visual experiences that occur across a range
only 4% of patients with organic disorders. In contrast,
of functional and organic disorders, such as poly-a study by Johnstone and colleagues on 328 recently
olpia/pallinopsia – where true percepts are experi-admitted psychotic patients – 23 of whom had under-enced multiple times – or metamorphopsia, where true
lying organic disorder – failed to demonstrate major
percepts are dimensionally altered; each of these could
phenomenological differences between patients with
be considered both an illusion and a hallucination
primary psychiatric disorders and those with organic
[27].
Additionally, the distinction between hallucina-disease in a manner that would allow such differences
tion and pseudohallucination has been driven by an
to stand as mainstays in the differential diagnosis of
assessment of the sufferer’s attribution – external ver-these two sets of disorders
[25]
. This study highlights
sus internal, “like” a true percept versus “is” a true per-the fact that astute clinic judgement is critical in deter-cept, or insight versus insightlessness; in reality, the
mining if hallucinations are secondary to neurological
sufferer’s experience is not so readily dichotomized,
and other diseases or are due to psychiatric disorders.

and it may be that the content and phenomenology of
Although hallucinations may occur in a number of
the experience is more closely tied to the underlying
modalities within the one individual, it is useful to con-pathology than its associated experiential quality.

sider them on a modality-by–modality basis, in view
One model of visual hallucinations is provided
of the differing etiological, biological, and treatment
by ffytche and colleagues. They propose that visual
facets associated with each type of hallucination.

pathway disorders produce characteristic simple VHs,
unfamiliar/malformed figures and landscape scenes,
Secondary visual hallucinations

whereas disorders involving the brainstem and/or
cholinergic dysfunction result in familiar figures, ani-Throughout history, visual hallucinations (VHs) have
mals, and frequent delusional elaboration. The clini-long been associated with concepts of insanity
[26].

cal utility of this model is supported by the fact that
Like other forms of aberrant sensory experience, VHs
the two groups tend to respond to different treatments
can occur in healthy individuals, functional psychi-

[27, 28]
. Furthermore, we would argue that an under-atric disorders, and organic states. An understanding
standing of the anatomy of visual experience, and how
of their experience in the latter can inform an under-lesion location at least partially predicts phenomenol-standing of the neurobiology of mental disorders as
ogy, leads to more appropriate investigation and man-well as the anatomy of normal human perception.

agement of VHs syndromes
[29].

Spectrum of visual perceptual

Visual hallucinations in normal

disturbances

individuals

As in other sensory modalities, VHs have been con-Individuals in the community who experience VHs in
sidered to fall at one extreme of a spectrum of per-the absence of a psychiatric or neurological disorder
ceptual experience. This spectrum extends from nor-are more likely to experience VHs of people, whereas
mal visual experience, through intense/vivid internal
those with functional psychiatric illness experience
visual imagery to illusions (a misperception of a true
nonpersonal VHs
[30].
It is not uncommon that the
percept), and finally frank hallucinations (a percept-experience of VHs has been incorporated into many
like experience in the absence of an external stimu-cultural understandings of human spiritual experi-lus, experienced as a true percept). This spectral model
ence, whereby VHs may be experienced in religious or
has served psychiatry well in categorizing auditory
spiritual rituals and are attributed to visions or spirit
hallucinations. It has generally allowed cleavage of
possession
[1, 31].

functional psychotic disorders, with their characteris-Visual hallucinations occur in a number of
tic external auditory phenomena and features of first-nondisease-associated states, perhaps the most com-rank, from nonpsychotic or post-traumatic syndromes
mon in the community being at the periphery of
where phenomena are more internal, “as if” experi-sleep, known as hypnagogic (entering sleep) and
23

ences with content often relating to past emotionally-hypnopompic (awakening) hallucinations; this is the
Introduction – Section 1

most prevalent form of hallucinations in any modality
of visual loss, such as the Charles Bonnet Syndrome
in the community
[5].
Sleep-associated hallucinations
[28, 29,
49, 50]
(Chapter 30). This has been supported
are far more common than daytime VHs, which
by functional magnetic resonance imaging (fMRI)
occur in less than 1% of the population
[5].
Hypn-studies, which show selective tonic activity in visual
agogic VHs are three to four times more common
cortical regions, even when not hallucinating
[51, 52].

than hypnopompic VHs in the general population,
Lesions anywhere in the visual system, from ocu-occurring in up to 5% of individuals, who most
lar structures through optic nerve, chiasm, and tract
commonly see another individual in the room
[5, 32].

structures, including ascending modulatory midbrain
The strongest predictors of sleep-associated VHs are
structures, can produce VHs, which are usually com-disorders associated with disregulation of sleep, such
plex in form
[29,
53, 54].
To correlate lesion location
as narcolepsy-cataplexy and the synucleinopathies
to type of VHs, Santhouse and colleagues used factor
(discussed later), as well as primary sleep disor-analysis in patients with complex visual hallucinations
ders, use of alcohol and substances, and psychiatric
(CVHs) to establish anatomical–phenomenological
disorders other than psychotic disorders
[5].

correlates, and demonstrated that landscapes and
VHs also occur as normal phenomena throughout
groups of figures reflected pathologically increased
the lifecycle. The “imaginary friend” occurs in 15% to
activity in the ventral temporal lobe, distorted faces
30% of children aged 2 to 10
[33,
34],
and is considered
activity around the superior temporal sulcus, and
a nonpathological developmental phase where reality
visual perseveration and palinopsia in the visual pari-testing is generally preserved
[34, 35]
but which may
etal lobe
[28].
Thus, at the anatomical level, although
be predictive of adolescent/adulthood emotional dis-simple VHs are most likely related to focal lesions of
turbance
[36].
Similarly, in bereavement, brief VHs of
the ocular apparatus or occipital cortex, complex VHs
a deceased individual may form part of a normal grief
occur when the quality or flow of information moving
reaction in both children
[37, 38]
and adults
[39–41].