Consider a 70-year-old man called Sentu, a pseudonym. His family suddenly raises serious concerns: he tries to embrace younger female relatives, kisses them without invitation and makes sexually suggestive remarks. The behavior causes distress, anger and misunderstanding, and relatives may conclude that his character has deteriorated in old age.
As a neurologist and psychiatrist, the author says he occasionally sees patients with similar complaints: obscene speech, inappropriate gestures, unwanted sexual behavior toward women other than their wives and violations of social boundaries.
A review of the patient’s history, however, can reveal a very different picture.
Family members may describe someone who was courteous, devout, honest and self-controlled throughout adolescence, youth and adulthood. His integrity and decency were a source of family pride, with no comparable complaint across seven decades of life.
The first question, then, is whether the change reflects character or a symptom of brain disease.
Behavior that begins suddenly in old age can be a neuropsychiatric symptom called disinhibition. Impaired frontal-lobe function reduces self-control, and a person may speak obscenely, lose restraint in sexual behavior, breach social rules or fail to recognize that the behavior is inappropriate, according to Stuss and Knight (2013) and Miller and Boeve (2017).
Disinhibition is not itself a disease but an important symptom of several conditions. It is most often seen in behavioral variant frontotemporal dementia (bvFTD). It can also occur after a frontal-lobe stroke or head injury, or with a brain tumor, Alzheimer’s disease, Lewy body dementia, Huntington’s disease, a manic episode of bipolar disorder, alcohol or drug use, and side effects from some medicines, according to Rascovsky et al. (2011) and the American Psychiatric Association (2022).
When an older person’s behavior changes suddenly and clearly, particularly after a very different earlier life, a full medical assessment should precede labels such as immoral or characterless. A mental state examination, neurological examination and, when needed, a brain MRI can play important roles in diagnosis, according to Darby and Dickerson (2017).
Not every unethical or socially inappropriate act reflects a character defect. It can sometimes be a quiet signal of brain disease. Proper assessment should come before a hasty judgment.
The article was written by Dr. Mohammad Sayeed Enam, an associate professor of psychiatry at Sylhet MAG Osmani Medical College and an international fellow of the American Psychiatric Association. He holds an MBBS from Dhaka Medical College, an MPhil in psychiatry and a Bangladesh Civil Service health cadre qualification.
References
American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders (DSM-5-TR). 5th ed., text revision. APA Publishing; 2022.
Darby RR, Dickerson BC. Continuum (Minneap Minn). 2017;23(2):440–456.
Miller BL, Boeve BF, eds. The Behavioral Neurology of Dementia. 2nd ed. Cambridge University Press; 2017.
Rascovsky K, Hodges JR, Knopman D, et al. Brain. 2011;134(9):2456–2477.
Stuss DT, Knight RT, eds. Principles of Frontal Lobe Function. 2nd ed. Oxford University Press; 2013.
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