Currently, there are over 200 mental health disorders that people can be diagnosed with.  Each with their own set of characteristics, symptomatology, and warning signs to look out for — it can be very difficult and overwhelming to try and make sense of them all.  How do you know what to look out for? And when? It can be even more difficult to look out for signs and symptoms when more than one diagnosis is thrown into the mix.  There is evidence to show that more than 50% of individuals diagnosed with one mental illness will be diagnosed with 1 or 2 more disorders within their life.  Furthermore, about 33% of individuals with one diagnosed mental disorder may have four more mental illnesses within their lifespan.  With such high rates of comorbidities among mental illnesses, the challenge of monitoring each of their presentations and symptoms can be especially difficult before a diagnosis.  Is a child presenting with a certain behavior doing this because it is part of growing up or is it a sign of a disorder?  How are you supposed to know if they are too young to show symptoms of mental disorders?  Conversely, you may have an adult friend or partner that may be doing things out of the ordinary to cause concern.  Could it be a sign of something wrong, or are you overthinking?  All of these questions can be so difficult to answer, and there are no hard guidelines as to how mental illnesses present themselves in individuals.  In this blog, we will attempt to clear up some confusion about how mental disorders manifest by discussing the average ages at which certain mental illnesses can show up.  We will discuss which mental disorders typically show up in younger aged children, and which ones may take more time to develop later in life.  Having the knowledge to detect symptoms as soon as they appear can help with early detection of mental illness, and this can make a significant impact on the outcomes that people with mental disorders eventually have.


When does mental illness start?

Unfortunately, it can be nearly impossible to predict when someone might develop a mental illness. These conditions can manifest at any time in a person’s life, and the average ages among which certain mental disorders occur is not yet established.  Whereas one person may develop a condition at 5 years old, another person may develop the same disorder at 25 years old.  However, data from the National Alliance on Mental Health show that half of all mental health disorders start before the age of 14 and three-quarters start before the age of 24!  Therefore, if a person has a mental illness, it will more than likely become prevalent in childhood, adolescence, or young adulthood.

Knowing that mental disorders typically present themselves in earlier life stages may be helpful, as children are usually monitored by some kind of authority figure who are more cognizant of behavioral and emotional changes they may go through.  To this same advantage, mental illnesses rarely present themselves in its full capacity overnight.  Typically, a parent, guardian, teacher, or even the person themselves notice some kind of shift in the way they think, act, or speak when a mental illness begins to develop. Knowing exactly what kinds of signs to look for and when to look for them can help individuals engage in early treatment of symptoms. Research shows that individuals with mental illness have a decreased life expectancy of about 10-15 years when compared with individuals without mental illness.  However, when individuals are treated with early intervention close to the time of a mental illness diagnosis, the benefits are maximal and outcomes can be improved.  For example, young individuals with early symptoms of psychosis have a 25% probability of developing the disorder within 3 years.  However, when these individuals go through clinical interventions targeted toward therapizing psychosis symptoms, there is evidence that supports a possibility of delaying and even preventing the full transition into full blown psychosis.  Therefore, searching for warning signs of mental disorders in young children and adolescents can be crucial to treating patients’ symptoms before they worsen over time.


Warning Signs to Look For

It may be easy to understand the importance of detecting and treating mental disorders early on, but what exactly should you be looking for?  How are you supposed to know if the tantrum your child just threw was just a normal part of development, or if they are experiencing mental distress?  Is that teenager acting out in angst, or are there more serious underlying issues that need to be addressed?  Children and adolescents go through very normal developmental periods when they are experiencing a major shift in emotions, behaviors, and thought patterns.  These shifts may be surprising and even out of the ordinary, but they are typical and give rise to many cliches about how teenagers are moody and two year olds are ‘terrible’.  Normal emotional development becomes not-so-normal when an occasional tantrum starts to happen every single day or that teenager begins to lock themselves in their room for weeks at a time.  When these changes happen, one should take a closer look at this behavior.

When making the decision to intervene, consider the following:

  • Behavior that deviates from their ‘norm’. – As mentioned above, everyone goes through periods of development when they may experience different emotions and thoughts to what is typical.  Everyone feels a little ‘off’ from time to time, and everyone knows what it feels like to have a weird day.  However, when a person is unable to participate in activities over multiple occasions and without explanation, then that is something to pay attention to.  If a child is used to doing certain tasks as part of their daily routine and suddenly stops doing these tasks and shows a serious lack of interest, that might be a sign that something is wrong.  Another example would be a sharp behavioral shift in an individual.  If a person is typically outgoing and socially interactive, but then they do not want to see anybody and they retreat for more than a few days or weeks, it may be a good idea to seek professional intervention.
  • Increase in depressive symptoms. – Everyone feels down from time to time.  Especially when difficult situations occur and various setbacks arise, the presentation of depressive moods or symptoms may not always be a cause for long-term concern. Sometimes, bad moods can really just be a reaction to outside factors. However, when these symptoms become ongoing and unrelenting, they can become a cause for action.  If you or someone you know experiences long bouts of irritability, difficulty concentrating, mood changes, decreased self-esteem, or decreased energy, it is important to check in with your mental health provider and discuss what may be going on.
  • Anxiety that is excessive or not proportionate to the situation. – Young children and adolescents might be subject to stress as they experience big life changes for the first time.  Entering a classroom for the first time, making their first friends, meeting a new teacher, playing a new sport or instrument, or visiting new places can be very overwhelming and stressful at such a young age.  They may also feel anxiety in daunting situations like taking a difficult math test or playing in a basketball game for the first time.  This is completely normal.  However, it can become problematic when children have anxious outbursts and reactions to situations that should not elicit that level of stress.  For example, if a child becomes fearful of school to the point that they refuse to go or cannot function while they are there, it is time to intervene.  Other anxious behaviors can manifest physically. For example, if they suddenly experience an increased heart rate, nausea or dizziness as a reaction to low-risk situations or environments, it may be time to bring them to see a mental health specialist.


Which mental disorders have the earliest onset?

In 2021, a meta-analysis done on 192 studies showed that the peak age of mental illness onset was around 14 ½ years old. As we discussed above, the onset of mental illness typically occurs in young childhood and adolescence, and the study shows that different mental disorders typically onset at different ages.  The average ages at which individuals typically develop these common mental disorders are as follows:

Evidenced by the range in ages above, there is no certain age at which a person can develop a mental disorder.  It can be very stressful and difficult to know how to recognize symptoms and signs of a mental disorder in yourself or the people around you.  Knowing that mental illness manifests over a long period of time gives hope to those who are diligent in noticing the behavioral and emotional differences that a person with suspected mental illness may be going through.  Having frequent conversations about mental health and being open to listening about their experiences is a great step to take if something may feel ‘off’ about someone you care about.  Trust that you know yourself and the people closest to you, and professional help is always available when things get confusing or overwhelming

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