Schizophrenia in adults is the most common illness causing psychosis (a loss of contact with reality, a lack of ability to tell what is real from what is not real in some way). Schizophrenia generally commences in late adolescence or less commonly after age 40 referred to as late onset schizophrenia in DSM-5. Seniors with schizophrenia will likely have had an early onset of the disease with chronic persistent mental illness spanning several decades. We do see patients developing psychosis for the first time in late life after age 75 due to a similar illness not defined in DSM-5 referred to as very late life schizophrenia-like psychosis, or due to episodes of severe depression, mania or delirium, and most commonly due to a neurodegenerative illness causing dementia.

Psychosis is expressed either chronically or in episodes that cause severe disturbances in behaviour, thinking and emotions with the following types of symptoms:

• fixed beliefs not open to change (delusions)
• impaired sensory perceptions (hallucinations)
• changes in thinking (cognitive symptoms)
• changes in behavior (disorganized behavior and negative symptoms)

DSM-5 defines delusions as fixed beliefs that are not open to change in light of conflicting evidence. Delusions are improbable and not understandable to people of the same-culture. The distinction between a delusion and a strongly held overvalued idea is sometimes difficult to make and depends in part on the degree of conviction with which the belief is held. Delusions are believed in with 100% probability, despite clear or reasonable contradictory evidence. While delusions are usually ‘false’ beliefs (and can often be diagnosed as such by their very improbability), they are not always so, and thus the distinction of being false was dropped from DSM-5. Rather their hallmark is that they are held on inadequate grounds; that is the belief is not arrived at through normal processes of logical thinking. This is important because one cannot always rely on the bizarreness or lack of accuracy of a belief to establish its unreasonable nature. Delusions are not simply impaired reasoning. Rather, delusional beliefs are resistant to conflicting evidence. That is the single most representative feature of delusions – being not bendable to reason.[i]

Psychosis is associated with cognitive impairment across all ages particularly in seniors.[ii] Individuals with schizophrenia who obtain age 65 or greater have more than twice the risk of developing dementia,[iii] i.e., cognitive and functional decline such that the person cannot live independently. Two key contrasting views of the course of cognitive function in schizophrenia exist.[iv] One view suggests that cognitive deficits become progressively worse throughout the long duration of the illness; that after an insidious onset, patients’ intellectual functions decline during the chronic phases of the illness.[v] [vi] This model suggests that aging causes a slowing of speed of processing information and learning new information and that these cognitive processes are impaired more so as a result of chronic psychosis. A second view suggests that marked cognitive abnormalities are present at the very onset of the illness[vii] [viii] and those cognitive deficits, once they arise; remain relatively stable such that no significant progression occurs.[ix] In my clinical experience the former model is more valid. The latter model appears to have been developed from studies of patients predominantly under age 75 and is not as generalizable.

The impact psychosis may or may not have on decision-making capacity is elucidated in the landmark decisions of Banks v Goodfellow[x] regarding criteria determining testamentary capacity and Starson v. Swayze[xi] regarding capacity to consent to treatment as per the Health Care Consent Act[xii] of Ontario. A good discussion of the legal definition of insane delusions can be found additionally in Banton v Banton.[xiii] An in-depth review of each of these case decisions would be beneficial for any individual assessing decision making capacity in persons suffering from psychosis.

 

References

[i] Bortolotti, L. (2010). Delusions and other irrational beliefs. Oxford University Press.

[ii] Loewenstein, D. A., Czaja, S. J., Bowie, C. R., & Harvey, P. D. (2012). Age-associated differences in cognitive performance in older patients with schizophrenia: a comparison with healthy older adults. The American Journal of Geriatric Psychiatry, 20(1), 29-40.

[iii] Hugh C. Hendrie, Wanzhu Tu, Rebeka Tabbey, Christianna E. Purnell, Roberta J. Ambuehl, Christopher M. Callahan. (2014). Health Outcomes and Cost of Care Among Older Adults with Schizophrenia: A 10-Year Study Using Medical Records Across the Continuum of Care. The American Journal of Geriatric Psychiatry, 22(5), 427-436.

[iv] Goldberg, T. E., & Gold, J. M. (1995). Neurocognitive functioning in patients with schizophrenia: an overview. In Psychopharmacology: The fourth generation of progress (pp. 1245-1257). Raven Press, New York.

[v] Miller R. Schizophrenia as a progressive disorder: relations to EEG, CT, neuropathological and other evidence. Prog Neurobiol 1989;33:17–44.

[vi] Harvey PD, Parrella M, White L, et al. Convergence of cognitive and adaptive decline in late-life schizophrenia. Schizophr Res 1999;35:77–84.

[vii] Censits DM, Ragland JD, Gur RC, et al. Neuropsychological evidence supporting a neurodevelopmental model of schizophrenia. Schizophr Res 1997;24:289–298.

[viii] Gold S, Arndt S, Nopoulos P, et al. Longitudinal study of cognitive function in first-episode and recent-onset schizophrenia.  Am J Psychiatry 1999;156:1342–1348.

[ix] Hyde TM, Nawroz S, Goldberg TE, et al. Is there cognitive decline in schizophrenia? A cross-sectional study. Br J Psychiatry 1994;164:494–500.

[x] Banks v Goodfellow (1870) L.R. 5 QB 549

[xi] Starson v. Swayze, [2003] 1 SCR 722, 2003 SCC 32

[xii] Health Care Consent Act, 1996, S.O. 1996, c. 2, Sched. A

[xiii] Banton v. Banton, 1998 CanLII 14926 (ON SC)