Persisting perception disorder - PDF document

z Persisting perception disorder 10 Progress in Neurology and Psychiatry January/February 2015www.progressnp.com A persisting perception disorder afterMBBS, BSc, MRCPsychHallucinogen persisting perception disorder is a disorder of uncertain aetiology occurringmainly after ‘classical’ hallucinogen use (mescaline, psilocybin, dimethyltryptamine andLSD) use. Here, the authors describe the case of a boy with similar symptoms developingafter he reported using cannabis seven times. CN Ellison-Wright_Layout 1 29/01/2015 10:13 Page 1 the reports. For example, in a fol-low-up study of 247 subjects whohad received LSD in conjunctionwith psychotherapy or in researchprotocols in the 1960s, only 2% ofreported that between 0–77% sub-jects suffered HPPD after LSD usewith the higher rates in studieswhere LSD was used illicitly ratherthan therapeutically, there wasongoing illicit drug use, or subjectsDifferential diagnosisAs well as the differential diag-noses noted in DSM-5, they sug-gested that others to consider werenormal visual experience (ing floaters), migraine, continueddrug intoxication, affective disor-ders, malingering, hypochondria-sis, anxiety disorders withpost-traumatic stress disorder.The cause of HPPD remains uncer-been suggested.Firstly, individualsmight have a heightened awarenessto normal visual phenomena.Secondly, the perceptual symptomsmight represent memories of theacute intoxication experienceaccompanied by a high level ofemotional distress. Thirdly, thethe drug exposure, of visual processing related to lossinhibitory inter-neurons. Withregard to this last hypothesis,Halpern and Pope comment that ifHPPD was due to some ‘kindling’phenomenon then one mightexpect that it would be more com-mon in individuals with a largenumber of LSD exposures ratherthan just a few – however, this doesnot appear to be the case.TreatmentHPPD can cause considerable dis-tress for some individuals for a pro-longed period. A large number oftreatments have been tried buthave mainly been described in caseseries rather than controlled trials.According to these reports, somecases have benefitted from usingsunglasses, psychotherapy, behav-ioural modification or pharmaco-logical agents.included antipsychotics (haloperi-antiepileptics (carbamazepine),clonidine, benzodiazepines, orSSRIs (sertraline).Conversely,some reports have described wors-More recent reports havewith the antiepileptic lamotrigineinhibitor used in the treatment ofParkinson’s disease.The boy described in this casesimilar to those reported in HPPD.His symptoms were persistent, last-ing (to the extent that psychiatricat one stage). Although he was ini-tially suspected to have a prodro-mal psychotic illness (such asschizophrenia), he did not experi-ence auditory hallucinations orfirst-rank symptoms, he retainedinsight into his visual experiencesand he did not benefit significantlyfrom taking risperidone.This raises the possibility hemight have developed an HPPD-like disorder induced by minimalcannabis use, perhaps in commonwith the very small number of casesdescribed in the literature of HPPDin subjects who reported previouscannabis but not hallucinogen use.Some strains of cannabis are nowvery rich in THC and can producemarked psychedelic experiences.The boy said that he recalledhad taken may have had otherthings mixed in with it, possiblyLSD. If this was the case, then hissymptoms might have been due toHPPD after minimal LSD use.Although a wide variety of contam-inants have been described incannabis (sand, sugar, glassgested that hallucinogens aremore likely to be added by usersrather than dealers. There is thepossibility that the boy’s friendsadulterated the cannabis; however,given the very volatile nature ofLSD crystals, the likelihood of itbeing effectively administered viasmoking in a joint is very lowindeed. Nevertheless, it is possiblethat he was spiked with LSD someother way, in food or a drink.In this case, the patient’s symp-toms worsened while he was pre-scribed risperidone. This isconsistent with reports of risperi-done exacerbating HPPD,although it may also have wors-ened his symptoms through its sideeffects of agitation and akathisia.During the course of the illness,the boy was referred for a secondopinion. At that time he said heexperienced permanent ‘visualsnow’ and he frequently saw‘floaters’ which looked like two-dimensional bubbles. At times thewalls appeared distorted or‘breathing’. He described deper-sonalisation and derealisation attimes. These symptoms were worsewhen his eyes were closed or whendown by school work’.He said prior to the onset of theCase notes z Persisting perception disorder 12 Progress in Neurology and Psychiatry January/February 2015www.progressnp.com CN Ellison-Wright_Layout 1 29/01/2015 10:13 Page 3